Water Quality Conditions of the North Platte River...

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Water Quality Conditions of the North Platte River

1996-2005

Wyoming Department of Environmental Quality

Water Quality Division

November 2007

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CONTENTS 1.0 EXECUTIVE SUMMARY ...........................................................................1 2.0 PURPOSE AND SCOPE ...........................................................................4 3.0 DESCRIPTION OF ASSESSMENT AREA ................................................5 4.0 DATA COLLECTION AND ANALYSIS .....................................................5 5.0 SEGMENT 1 - UPSTREAM OF SEMINOE RESERVOIR ..........................9

5.1 Environmental Setting ..................................................................................... 9 5.2 Hydrologic Conditions...................................................................................... 9 5.3 Chemical Quality ............................................................................................ 10 5.4 Physical Condition.......................................................................................... 12 5.5 Aquatic Life Condition.................................................................................... 13

6.0 SEGMENT 2 – SEMINOE RESERVOIR TO CASPER, WY ....................18 6.1 Environmental Setting ................................................................................... 18 6.2 Hydrologic Conditions.................................................................................... 18 6.3 Chemical Quality ............................................................................................ 21 6.4 Physical Condition.......................................................................................... 22 6.5 Aquatic Life Condition.................................................................................... 23

7.0 SEGMENT 3 – CASPER, WY TO GLENDO RESERVOIR ......................26 7.1 Environmental Setting ................................................................................... 26 7.2 Hydrologic Conditions.................................................................................... 26 7.3 Chemical Quality ............................................................................................ 27 7.4 Physical Condition.......................................................................................... 28 7.5 Aquatic Life Condition.................................................................................... 29

8.0 SEGMENT 4 – GLENDO RESERVOIR TO WY/NE STATELINE ............32 8.1 Environmental Setting ................................................................................... 32 8.2 Hydrologic Conditions.................................................................................... 32 8.3 Chemical Quality ............................................................................................ 34 8.4 Physical Condition.......................................................................................... 35 8.5 Aquatic Life Condition.................................................................................... 36

9.0 QUALITY ASSURANCE/QUALITY CONTROL ......................................37 10.0 SUMMARY AND CONCLUSIONS ..........................................................38 11.0 RECOMMENDATIONS ............................................................................41 12.0 SIGNATURES ..........................................................................................41 13.0 LITERATURE CITED ...............................................................................42 14.0 APPENDIX...............................................................................................45

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MAPS Map 1 – The North Platte River watershed and associated monitoring stations. Red dots represent WDEQ stations where chemical, physical and biological data were collected, yellow dots represent water-quality only WDEQ stations, green dots represent USGS fixed stations and gray dots represent SERCD stations..... 6 Map 2 – The North Platte River watershed with ecoregions and associated monitoring stations. Red dots represent WDEQ stations where chemical, physical and biological data were collected, yellow dots represent water-quality only WDEQ stations, green dots represent USGS fixed stations and gray dots represent SERCD stations.............................................................................................. 7 Map 3 – The North Platte River watershed with bioregions and associated monitoring stations. Red dots represent WDEQ stations where chemical, physical and biological data were collected, yellow dots represent water-quality only WDEQ stations, green dots represent USGS fixed stations and gray dots represent SERCD stations............................................................................................ 16 FIGURES Figure 1 – Annual hydrograph (1938-2005) of mean daily streamflow and daily streamflow for selected years at USGS station 06630000 (North Platte River above Semionoe Reservoir) ........................................................................................... 9 Figure 2 – WY RIVAPCS and WSII biological condition scores for stations SERCD1 and SERCD2 in the Wyoming Basin bioregion and associated numeric aquatic life-use thresholds. ........................................................................................... 17 Figure 3 – Annual hydrograph (1995-2005) of mean daily releases from Kortes Dam .................................................................................................................................. 18 Figure 4 – Annual hydrograph (1995-2005) of mean daily releases from Pathfinder Dam............................................................................................................... 19 Figure 5 – Annual hydrograph (1995-2005) of mean daily releases from Gray Reef Dam......................................................................................................................... 20 Figure 6 – Annual hydrograph (1950-2005) of mean daily streamflow at USGS station 06652000 (North Platte River at Orin, Wyoming.......................................... 26 Figure 7 – Annual hydrograph (1995-2005) of mean daily releases from Guernsey Dam................................................................................................................ 32 Figure 8 – Annual hydrograph (1928-2005) of mean daily streamflow at USGS station 06674500 (North Platte River at WY/NE Stateline) ..................................... 33

TABLES Table 1 - Water quality limited segments described in the 1996 305(b) Report and 303(d) List.................................................................................................................. 4 Table 2 - Descriptive information on North Platte River WDEQ/WQD, USGS, and SERCD stations by segment .......................................................................................... 8

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LIST OF ACRONYMS EPT Ephemeroptera, Plecoptera and Trichoptera HUC Hydrologic Unit Code NGP Northwestern Great Plains Ecoregion SERCD Saratoga-Encampment-Rawlins Conservation District SR Southern Rockies Ecoregion TMDL Total Maximum Daily Load USBOR United States Bureau of Reclamation USEPA United States Environmental Protection Agency USGS United States Geological Survey WB Wyoming Basin Ecoregion WHP Western High Plains Ecoregion WDEQ/WQD Wyoming Department of Environmental Quality/Water Quality Division WGFD Wyoming Game and Fish Department WSII Wyoming Stream Integrity Index WY RIVPACS Wyoming River Invertebrate Prediction and Classification System WYPDES Wyoming Pollutant Discharge Elimination System

Author: Eric Hargett (WDEQ/WQD) This document was peer reviewed by Mark Conrad (WDEQ/WQD), Lanny Goyn (WDEQ/WQD) and Jeremy Zumberge (WDEQ/WQD). Cover photo: North Platte River near Casper, Wyoming.

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1.0 EXECUTIVE SUMMARY

Stream assessments are performed under Section 305(b) of the Clean Water Act to evaluate the

extent to which Wyoming waterbodies meet the goals of the Clean Water Act and support

designated uses established under Chapter 1 of the Wyoming Department of Environmental

Quality-Water Quality Division (WDEQ/WQD) Water Quality Rules and Regulations (WDEQ/WQD

2007). Water quality in Wyoming is protected for designated uses such as fisheries, aquatic life

other than fish, drinking water, fish consumption, recreation, agriculture, industry and scenic

value. Stream assessments are performed by the WDEQ/WQD Watershed Management

Section’s Monitoring Program. Representative and valid data collected by other federal, state

and local entities are also used in stream assessments where appropriate.

Data and reports from stream assessments are later combined with information gathered by the

WDEQ/WQD and other federal, state and local entities to make designated use support

determinations which are summarized in the biennial Wyoming 305(b) State Water Quality

Assessment Report and 303(d) List of Waters Requiring TMDLs.

From 1996 to 2004, the WDEQ/WQD Monitoring Program conducted stream assessments on the

North Platte River where chemical, physical and biological information were collected. The

objectives of these assessments were to 1) document baseline conditions and 2) evaluate water

quality conditions to determine whether designated uses were supported on their dates of

sampling. Additional data collected by the United States Geological Survey (USGS) from 1996 to

2005 and the Saratoga-Encampment-Rawlins Conservation District (SERCD) from 1997 to 2005

were also used to characterize baseline conditions and evaluate designated use support of these

waters. This report contains a summary of the analysis performed on the 1996-2005 dataset and

conclusions on designated use support for the North Platte River.

Exceedences of the federally recommended nutrient reference conditions for nitrate-nitrogen and

total phosphorus and visual indicators of nutrient enrichment were present in several segments of

the North Platte River downstream of Saratoga, Wyoming to the Wyoming/Nebraska stateline

from 1998 to 2005. Non-point source runoff and groundwater contributions from agricultural

lands, discharges from municipal wastewater treatment plants, stormwater runoff, malfunctioning

septic systems and possible nutrient-rich hypolimnetic reservoir releases are suspected sources.

This information along with visual observations suggests nutrient enrichment is occurring in the

North Platte River. However, without adopted statewide numeric nutrient criteria along with

quantitative indicators of nutrient enrichment, the available information is insufficient to conclude

whether nutrient enrichment is limiting the ability of the North Platte River to support designated

uses.

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Selenium concentrations in the North Platte River near the Kendrick Project Area and City of

Casper exceeded the chronic aquatic life criterion on several occasions from 1996-2005. These

selenium data support the current State of Wyoming 303(d) listing of the North Platte River

upstream and downstream an undetermined distance from the City of Casper for exceedence of

the chronic aquatic life selenium criterion. The primary source of selenium is irrigation return

flows to the North Platte River from the Kendrick Project and other areas where soils are naturally

elevated in selenium.

There were no numeric criteria exceedences for other water chemistry parameters sampled.

Parameters without numeric criteria were within the expected range of conditions for the North

Platte River. Available data were insufficient to conclude whether fish consumption and

recreational uses on the North Platte River were supported.

Overall, fecal coliform bacteria concentrations in the North Platte River were below single-sample

maximum and/or geometric mean criteria for high use swimming areas on waters protective of

primary contact recreation. The exception was a stretch of the river downstream of the City of

Casper wastewater treatment facility where one sample exceeded the single-sample maximum

criterion. More samples, however, are needed both spatially and temporally to make an effective

determination of primary contact recreational use support.

The North Platte River channel from the Wyoming/Colorado stateline downstream below Casper,

Wyoming was generally characterized by stable banks, sufficient riparian vegetative cover and

coarse material and adequate in-stream habitat for aquatic life. Anthropogenic activities in the

Sage Creek watershed, a tributary to the upper North Platte River, historically resulted in

increased erosion and sediment loading to the North Platte River. Best management practices

and improved land uses implemented in the watershed from 1998 to 2005 have reduced excess

sediment loading to the North Platte River. Much of the North Platte River from near Douglas,

Wyoming downstream to the Wyoming/Nebraska stateline is characterized by excessive

aggradation that has influenced the complexity and diversity of in-stream habitat for aquatic life.

Bank scour, channel changes, regulated sediment conveyances, sediment in irrigation return

flows and municipal stormwater drains and reductions in sediment carrying capacity from

irrigation diversions and reservoir operations are the likely contributors.

Biological condition of the North Platte River upstream of Saratoga, Wyoming was comparable to

expected conditions determined to be representative of the upper North Platte River. This

segment is considered fully supportive of fisheries and other aquatic life uses when samples were

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collected in the late 1990’s. However, because data from this segment of the North Platte River

is greater than 5 years old and it is unknown how the recent drought conditions have affected the

reach, a recent use-support determination cannot be made without further data collection.

Biological data collected on the North Platte River downstream of Saratoga, Wyoming to Seminoe

Reservoir (particularly near Sage Creek) indicated a decline in biological condition from 1999 to

2002 predominantly due to low flows associated with drought. Sediment loading from Sage

Creek possibly contributed to the decline in biological condition of the North Platte River below

Sage Creek. Biological condition then improved from 2002 to 2005. It’s likely that improved flow

conditions and sediment reduction efforts in Sage Creek have contributed to the positive

biological condition trend. Further monitoring is needed however, to document whether biological

condition continues to improve before making a determination on fisheries and aquatic life use

support for this segment.

Flow manipulations and associated physicochemical and physical habitat changes such as

habitat alterations, scouring, bank erosion and sedimentation from reservoir operations and

irrigation diversions appear to have the most significant impact to the ability of the remaining

segments of the North Platte River to support fisheries and other aquatic life uses. Other impacts

include selenium loading in the Kendrick Project Area near Casper, Wyoming, additional

sediment loading from human sources and possible nutrient enrichment. The compounding

effects of these impacts in addition to the absence of an expected biological reference condition

for large flow-regulated segments of the North Platte River present difficulties in making a

conclusive determination on aquatic life use support at this time.

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2.0 PURPOSE AND SCOPE

The Monitoring and Assessment Program of the Wyoming Department of Environmental Quality-

Water Quality Division (WDEQ/WQD) assesses the water quality and makes use-support

determinations for streams and rivers in Wyoming. From 1996-2005, WDEQ/WQD completed

one-time assessments at 26 stations on the North Platte River, which provided baseline data on

the biological, chemical, and physical conditions. Also during this time period, Saratoga-

Encampment-Rawlins Conservation District (SERCD) collected annual biological or monthly

chemical data at six stations and the United States Geological Survey (USGS) collected quarterly

chemical and daily discharge data from four fixed stations. Analysis of water quality data for the

USGS stations was limited to data collected from January 1, 1990 to December 31, 2004.

Supplemental daily discharge information from the United States Bureau of Reclamation

(USBOR) reservoir dam outflow stations was also available during this time period.

The primary objective of this report is to evaluate the water quality conditions of the North Platte

River with respect to Wyoming water quality standards to determine whether designated uses of

the North Platte River are supported using the aforementioned information collected from 1996-

2005. This information will be used by WDEQ/WQD to address conclusions from the State of

Wyoming’s 1996 305(b) Report and 303(d) List which indicated several segments of the North

Platte River were water quality limited due to anthropogenic and/or natural influences, however,

these listings were based largely on qualitative information (Table 1).

Table 1 - Water quality limited segments described in the 1996 305(b) Report and 303(d) List. Segment # Segment

Description Designated Uses Suspected

Impairment Suspected Sources

10180002-034 Sugar Ck. to Seminoe Reservoir

Non-supportive of drinking water

Siltation, organics, and metals

Rangeland, highway/road/bridge construction and riparian vegetation removal

10180003-032 Miracle Mile Partially-supportive for aquatic life and cold-water fisheries

Flow alteration, organics, unknown

Rangeland, irrigated crop land, flow problems and riparian vegetation removal

10180007-018 Pathfinder to Alcova Reservoirs

Partially-supportive for aquatic life and cold-water fisheries

Flow alteration and unknown

Irrigated crop land and flow problems

10180007-016 Alcova Reservoir to Bates Ck.

Partially-supportive for drinking water and agriculture and threatened for cold-water fisheries

Siltation, flow alteration, metals and unknown

Rangeland, irrigated crop land, pasture land, flow problems and riparian vegetation removal

10180007-015 Bates Ck. to Poison Spider Ck.

Non-supportive for aquatic life, fish consumption and drinking water and threatened for cold-water fisheries

Siltation, organics, metals, other inorganics and unknown

Rangeland, irrigated crop land, pasture land, flow problems and riparian vegetation removal

10180008-007 Glendo Reservoir to Bear Ck.




10180008-006 Bear Ck. to Guernsey Reservoir




10180009-001 Deer Ck. to WY/NE stateline

Threatened for cold-water fisheries and drinking water

Siltation and unknown Rangland and irrigated crop land

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3.0 DESCRIPTION OF ASSESSMENT AREA

From its origins in the mountains of north-central Colorado, the North Platte River transverses

small mountain ranges, inter-montane desert basins and arid regions of the Great Plains along its

route through Wyoming before entering Nebraska (Map 1). The North Platte River at the

Wyoming/Nebraska stateline drains an almost 23,000 mi2 watershed situated within five level III

ecoregions: Middle Rockies, Northwestern Great Plains, Southern Rockies, Western High Plains

and the Wyoming Basin (Omernik and Gallant 1987) (Map 2). Greater than two-thirds of the

watershed is comprised of grassland and sagebrush steppe in the Northwestern Great Plains,

Western High Plains and Wyoming Basin ecoregions. Coniferous forests, aspen groves and

alpine tundra in the Middle Rockies and Southern Rockies ecoregions makes up the remainder.

The bedrock geology of the North Platte River watershed is diverse with a variety of sedimentary

and marine deposits in the arid basin and plains regions and granitics in the mountain ranges.

In addition to its ecological diversity, the North Platte River and many of its major drainage

basins, is an intensively flow regulated system. Several reservoirs regulate stream flow in the

river for purposes of agricultural irrigation, flood control and hydroelectric power generation.

Streamflows are further manipulated by direct irrigation diversions from the North Platte River and

its tributaries and by return flows. Municipal water utilities, coal-fired powerplants, industry, and

recreation represent other uses of the North Platte River water and its tributaries. Grazing is

prevalent throughout the system while timber harvesting is an important land use in the

mountainous areas. Oil and gas are extracted in areas south of Rawlins, Wyoming and

southwest and east of Casper, Wyoming. Coal strip-mines are located near the mouth of the

Medicine Bow River on the east side of Seminoe Reservoir and north of Glenrock, Wyoming.

Most mining along the North Platte River and within its watershed are sand and gravel

operations. Several Wyoming Pollutant Discharge Elimination System (WYPDES) permitted

point sources discharge effluent directly to the North Platte River or its tributaries. These

permitted facilities are predominantly oil treaters and municipal wastewater treatment facilities.

4.0 DATA COLLECTION AND ANALYSIS

Effective evaluation of water quality data on the North Platte River requires an understanding of

how both natural and anthropogenic processes influence the physical, chemical, and biotic

characteristics along various segments of the river. Therefore, to adequately explain the variation

in water quality conditions of the basin and whether designated uses are supported, the North

Platte River was stratified into four segments. Segments were stratified based primarily on

similarities in ecoregion, geology, land use, and hydrologic regime. The four segments are:

Upstream of Seminoe Reservoir; Seminoe Reservoir to Casper, Wyoming; Casper, Wyoming to

Glendo Reservoir; and Glendo Reservoir to the WY/NE stateline. These segments were

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Map 1 – The North Platte River watershed and associated monitoring stations. Red dots represent WDEQ stations where chemical, physical and biological data were collected, yellow dots represent water-quality only WDEQ stations, green dots represent USGS fixed stations and gray dots represent SERCD stations.

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Map 2 – The North Platte River watershed with ecoregions and associated monitoring stations. Red dots represent WDEQ stations where chemical, physical and biological data were collected, yellow dots represent water-quality only WDEQ stations, green dots represent USGS fixed stations and gray dots represent SERCD stations.

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compared and contrasted in order to better understand the natural and human-induced factors that affect

water quality conditions of the North Platte River. All WDEQ/WQD data collection, analysis, and models

used in to evaluate North Platte River data were conducted in accordance with approved procedures

(Hargett et al. 2007; Hargett et al. 2005; Hargett and Zumberge 2006; King 1993 and WDEQ/WQD 1998,

2001a, 2001b, and 2004). A list of all monitoring stations and associated data types used in the report

can be found in Table 2:

Table 2 - Descriptive information on North Platte River WDEQ/WQD, USGS, and SERCD stations by segment (Maps 1-3).

Station ID Record *Data Entity Legal Latitude Longi tude

Upstream of Seminoe Reservoir SR12 1997 C B P WDEQ/WQD SENW of Sec. 36, T14N, R81W 41.143606◦ -106.450625◦ SR24 1996 C B P WDEQ/WQD NWNE of Sec. 23, T15N, R82W 41.258592◦ -106.574906◦ WB5 1997 C B P WDEQ/WQD NWNE of Sec. 28, T16N, R83W 41.332831◦ -106.722797◦ SERCD-W1 1998-2001 C SERCD Sec. 11, T17N, R84W 41.460000◦ -106.810000◦ SERCD-W2 1998-2001 C SERCD SE of Sec. 7, T18N, R84W 41.550000◦ -106.890000◦ WB29 1997 C B P WDEQ/WQD SWSW of Sec. 27, T19N, R85W 41.587633◦ -106.957947◦ SERCD1 1997-2005 B SERCD SWSW of Sec. 27, T19N, R85W 41.587633◦ -106.957947◦ WB220 2004 C B P WDEQ/WQD NWNW of Sec. 11, T19N, R85W 41.638478◦ -106.940186◦ SERCD2 1997-2005 B SERCD NWNE of Sec. 30, T20N, R84W 41.683342◦ -106.890664◦ WBI21 1997 C B P WDEQ/WQD NWNE of Sec. 30, T20N, R84W 41.683342◦ -106.890664◦ SERCD-W3 1998-2001 C SERCD Sec. 35, T21N, R85W 41.750000◦ -106.940000◦ WB174 2002 C B P WDEQ/WQD NESW of Sec. 24, T22N, R86W 41.862786◦ -107.055753◦

06630000

Discharge: 1939-2005; Water Quality: 1966-2004

C USGS SW of Sec. 13, T22N, R86W 41.872222◦ -107.056944◦

SERCD-W4 1998-2001 C SERCD SW of Sec. 13, T22N, R86W 41.872222◦ -107.056944◦ Seminoe Reservoir to Casper, WY WB175 2002 C B P WDEQ/WQD NWNW of Sec. 22, T26N, R84W 42.214297◦ -106.878725◦ WB181 2002 C B P WDEQ/WQD SESW of Sec. 24, T29N, R84W 42.464572◦ -106.846333◦ WB179 2002 C WDEQ/WQD NESW of Sec. 8, T30N, R82W 42.578803◦ -106.695067◦ WB176 2002 C B P WDEQ/WQD NESW of Sec. 36, T32N, R82W 42.695292◦ -106.612353◦ WB177 2002 C WDEQ/WQD SESE of Sec. 10, T32N, R81W 42.749264◦ -106.524292◦ WB178 2002 C WDEQ/WQD SESE of Sec. 10, T32N, R81W 42.749711◦ -106.523064◦ Casper, WY to Glendo Reservoir aCASPER1 2003 C WDEQ/WQD NWNW of Sec. 2, T33N, R79W 42.864075◦ -106.293781◦ bCASPER2 2003 C WDEQ/WQD NWNW of Sec. 2, T33N, R79W 42.863719◦ -106.293347◦

06645000 Water Quality: 1949-2004 C USGS SENW of Sec. 4, T33N, R78W 42.858889◦ -106.211389◦

aDOUG1 2003 C WDEQ/WQD NESW of Sec. 17, T32N, R71W 42.744717◦ -105.398172◦ bDOUG2 2003 C WDEQ/WQD NESW of Sec. 17, T32N, R71W 42.743150◦ -105.399472◦ NGP193 2004 C B P WDEQ/WQD NENE of Sec. 29, T32N, R71W 42.718478◦ -105.387147◦

06652000


C USGS SESW of Sec. 17, T31N, R69W 42.652528◦ -105.158611◦

Glendo Reservoir to the Wyoming/Nebraska Stateline NGP151 2002 C B P WDEQ/WQD SWNW of Sec. 30, T29N, R67W 42.460617◦ -104.949947◦ NGP150 2002 C B P WDEQ/WQD SWSE of Sec. 7, T28N, R67W 42.411478◦ -104.937711◦ WHP36 2002 C B P WDEQ/WQD NESW of Sec. 2, T27N, R67W 42.345058◦ -104.864900◦ aGUERN1 2003 C WDEQ/WQD NWSE of Sec. 2, T26N, R66W 42.256028◦ -104.736775◦ WHP35 2002 C B P WDEQ/WQD SESE of Sec. 30, T25N, R62W 42.103575◦ -104.345653◦ WHP34 2002 C B P WDEQ/WQD SESE of Sec. 15, T24N, R61W 42.045539◦ -104.167047◦ WHP33 2002 C B P WDEQ/WQD NWNE of Sec. 23, T24N, R61W 42.045414◦ -104.162925◦ WHP32 2002 C B P WDEQ/WQD SWSW of Sec. 33, T24N, R60W 42.004369◦ -104.089950◦

06674500


C USGS SESE of Sec. 3, T23N, R60W 42.988611◦ -104.052778◦

*Data Type: C = Chemical, B = Biological, P = Physical; a Above wastewater treatment facility, b Below wastewater treatment facility

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5.0 SEGMENT 1 - UPSTREAM OF SEMINOE RESERVOIR

5.1 Environmental Setting

This segment encompasses the North Platte River and its watershed within the Upper North Platte sub-

basin (HUC 10180002) (Map 1). Map 2 shows the watershed situated within two level III ecoregions:

Southern Rockies and Wyoming Basin (Omernik and Gallant 1987). Coniferous forests, subalpine

meadows and alpine tundra characterize the Southern Rockies while land cover throughout the arid

Wyoming Basin consists of high-desert grasses and sagebrush. Primary land uses along this segment

are livestock grazing and irrigated hay production. This segment drains a watershed comprised primarily

of moderate to minimally weathered granitic and metamorphic materials in the mountains and

sedimentary formations in the basin (USGS 1985). The North Platte River is a Class 1 water from the

Wyoming/Colorado stateline downstream to the confluence with Sage Creek (WDEQ/WQD 2007). The

remainder of the segment from the confluence with Sage Creek downstream to Seminoe Reservoir is

Class 2AB (WDEQ/WQD 2007). Designated uses protected for both Class 1 and 2AB waters are drinking

water supplies, non-game fisheries, cold-water fisheries, fish consumption, aquatic life other than fish,

primary contact recreation, wildlife, industry, agriculture and scenic value.

5.2 Hydrologic Conditions

Melting of the winter snowpack in the mountains of north-central Colorado and the Medicine Bow and

Sierra Madre ranges of Wyoming is the predominant source of flow to the North Platte River. The river

responds to the snowmelt

beginning around March/April

with a peak in discharge generally

during early June (Figure 1).

Streamflows are generally lowest

in September with small increases

in discharge for October and

November due to melting of fall

snows, rain events, and a

reduction in vegetative

evapotranspiration. Streams that

drain the snowmelt have origins in

the Southern Rockies ecoregion

though many flow into the

Wyoming Basin ecoregion to their

confluence with the North Platte

River. Many streams that

originate in the Wyoming Basin

Figure 1 – Annual hydrograph (1938-2005) of mean daily streamflow and daily streamflow for selected years at USGS station 06630000 (North Platte River above Seminoe Reservoir).

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

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1-M

ar

1-A

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1-M

ay

1-Ju

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Dis

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Mean Daily for 68 year record 1999

2000 2001

2002 2003

2004 2005

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are intermittent or ephemeral and contribute flows to the North Platte River primarily from local snowmelt

and precipitation events. Major tributaries to the river in this segment include Big Creek, Brush Creek,

Douglas Creek, Encampment River, French Creek, Jack Creek, Pass Creek, Sage Creek, Saint Mary’s

Creek and Spring Creek. Irrigation withdrawals generally have minimal influence on streamflows in this

segment of the North Platte River. Most water diverted from the North Platte River is used to irrigate

fields located in the river and stream valleys.

North Platte River surface water quality is influenced by natural processes and point and non-point source

pollutants associated with human activities. Turbidity, concentrations of suspended sediment and major

ions (e.g. sulfate) are influenced by geologic materials in the watershed. For example, the North Platte

River transitions from a clear mountain stream in the headwaters and throughout much of the river valley

into a turbid and alkaline system downstream of tributaries that drain erodible soils and sedimentary

formations of the Wyoming Basin. These same tributaries carry large sediment loads to the North Platte

River in response to precipitation events. Supplemental flows from permitted point source discharges are

minor and are primarily effluent from municipal wastewater treatment facilities. Agricultural practices and

timber harvesting along the river and its tributaries may also influence concentrations of bacteria,

suspended and bed sediment, nutrients and other chemical analytes.

5.3 Chemical Quality

(See Appendices 1 and 2-1 thru 2-5 for dataset) Based on the available information for the period of

record, water temperatures in this segment of the North Platte River were generally below the

WDEQ/WQD (2007) maximum criteria of 20◦C for a cold-water fishery. On occasion, water temperatures

exceeded 20◦C during the months of July and August when low flows were prevalent. Throughout most

of the segment, dissolved oxygen concentrations were generally above the acceptable one-day minimum

criterion of 8 mg/L that is considered protective of early aquatic life stages in Class 1 and 2AB waters

(WDEQ/WQD 2007). Instantaneous dissolved oxygen concentrations can fall to 7 mg/L or less during the

summer months due to low flows, shallow depth and warmer water temperatures. With the exception of a

few outliers, all pH values throughout the segment were within the limit of 6.0-9.0 (WDEQ/WQD 2007).

Though WDEQ/WQD currently has no numeric water quality criteria for total phosphorous and nitrate-

nitrogen, recent guidance by the USEPA (2000a) recommends maximum total phosphorous and nitrate-

nitrogen concentrations of 0.006 mg/L and 0.00 mg/L, respectively, to protect aquatic life uses for streams

in the Southern Rockies ecoregion. Similarly, USEPA recommended maximum total phosphorous and

nitrate-nitrogen concentrations of 0.022 mg/L and 0.025 mg/L, respectively for the Wyoming Basin

ecoregion (USEPA 2000b). It’s important to note that USEPA’s recommended nutrient reference

conditions were developed for a broad ecoregion and may not be represent the maximum nutrient

concentrations protective of designated uses in the North Platte River. Nutrient concentrations at

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WDEQ/WQD stations were below detection (<0.1 mg/L), though this information is not particularly

informative since the detection limit was greater than the recommended concentrations (Appendix 2-1).

Median total phosphorous concentrations at three SERCD stations (SERCD-W1, W2 and W3) were

between 0.09 and 0.11 mg/L, exceeding the recommended maximum concentration for the Wyoming

Basin (Appendices 2-1 thru 2-4). Though elevated, there was no documented evidence suggesting

nutrient enrichment such as excessive macrophyte or algal growth and/or super-saturated dissolved

oxygen conditions at SERCD sites on the dates of sampling. Natural sources of phosphorous in the

lower portion of the segment may include soil and sediment weathered from marine shales. At USGS

station 06630000 above Seminoe Reservoir, median concentrations of total phosphorous and nitrate-

nitrogen were 0.02 mg/L and 0.05 mg/L, respectively with nitrate-nitrogen exceeding the recommended

maximum concentrations for the Wyoming Basin. Nitrate-nitrogen values at USGS station 06630000

should be used with caution since many of the values were estimated and may not be accurate. The

elevated nutrient values raise questions of whether anthropogenic activities in the watershed contribute to

nutrient enrichment in the North Platte River downstream from Saratoga, Wyoming or if nutrient

concentrations are representative of background. Though speculative at this point, anthropogenic

nutrient sources may include effluent from municipal wastewater treatment plants, non-point source runoff

from agricultural lands, and malfunctioning septic systems.

Conductivity, sulfate, alkalinity, total dissolved solids (TDS), total suspended solids (TSS), and hardness

all increased with distance downstream due to elevated concentrations of dissolved and suspended

solids in streams draining sedimentary materials of the Wyoming Basin. As the North Platte River comes

in the contact with marine shales in the lower portions of the segment, chloride concentrations increased,

although remained below the 230 mg/L criterion protective of aquatic life uses (WDEQ/WQD 2007).

Concentrations for total selenium were all less than the 5 ug/L criterion that is protective for aquatic life

uses (WDEQ/WQD 2007). Dissolved arsenic concentrations measured on the North Platte River above

Seminoe Reservoir (USGS station 06630000) were below the maximum human health, fish consumption

and drinking water criterion of 10 ug/L (WDEQ/WQD 2007). At this same station, all dissolved

concentrations (with the exception of one lead value outlier) of zinc, lead, copper, and cadmium were

below the hardness-dependent aquatic life use chronic criteria of 179.7, 4.3, 13.7, and 3.2 ug/L,

respectively (WDEQ/WQD 2007)1.

With the exception of one outlier, all fecal coliform concentrations from samples collected at the North

Platte River above Seminoe Reservoir (USGS station 06630000), from April 1 to October 31, were below

the single-sample maximum E. coli concentration of 235 col/100 mL for high use swimming areas on

1 The aquatic life use chronic criteria for metals were calculated with a mean hardness concentration of 164 mg/L derived from 1965-1985 data. This was done because hardness, calcium and/or other cations were not analyzed concurrently with the metals samples collected in the 1990s.

12

waters designated for primary contact recreation (WDEQ/WQD 2007). Because E. coli are a subset of

fecal coliform bacteria, it is scientifically acceptable, in this circumstance, to conclude that when the fecal

coliform concentration in a sample is less than the E. coli criteria, then the concentration of E. coli in the

same sample is also less than the E. coli criteria.

5.4 Physical Condition

(See Appendix 2-6 for dataset) Habitat conditions for each WDEQ/WQD station were assessed with the

use of the fast-water (>10% of stream reach characterized by riffle/run habitats) or large river qualitative

habitat assessment procedure (WDEQ/WQD

2004). Total habitat condition scores for each

station were evaluated for their percent

comparability to the mean habitat condition

score of North Platte River reference sites within

an ecoregion. For this segment, WDEQ/WQD

station SR12 is considered reference quality for

the portion of the North Platte River that flows

through the Southern Rockies ecoregion.

Similarly, WDEQ/WQD stations SR24, WB5,

WB29, and WB220 are all considered reference quality for the North Platte River in the Wyoming Basin

ecoregion (station SR24 is considered more representative of the Wyoming Basin than the Southern

Rockies).

In general, streambanks were stable with adequate riparian vegetation and coarse material to protect the

banks and minimize erosion during high flows. Banks at station WB174 were considered moderately

unstable and susceptible to erosion due to heavy utilization of the riparian area for grazing and recreation.

Bed substrate is a cobble/gravel mix and marginally embedded (relatively free of fine sediment covering

or surrounding the particles). Riffle embeddedness is generally more prevalent downstream of Sage

Creek, due to high sediment loading from this and other Wyoming Basin tributaries. Sage Creek has a

naturally high sediment load due to the erosive soils and geology and arid climate throughout its

watershed. However, dam failures, road building and historical grazing practices resulted in increased

erosion and sediment loading from this creek to the North Platte River. For this reason, WDEQ/WQD

included Sage Creek on Table C of the State of Wyoming’s 303(d) List of impaired waters in 1996. In

1998, SERCD in cooperation with land owners, Bureau of Land Management (BLM), Natural Resource

Conservation Service (NRCS) and Wyoming Game and Fish Department (WGFD) began a 319

watershed improvement project on Sage Creek (which included the North Platte River at the Sage Creek

confluence) that involved implementation of best management practices (BMPs) and improved land use

management to reduce sediment loading from anthropogenic sources. BMPs were implemented in the

WDEQ/WQD Station SR12 (1997)

13

Sage Creek watershed from 1998 to 2005. Data collected as part of this project indicate riparian and

range conditions have improved and suggest a reduction in sediment loading (SERCD 2006). Post-BMP

data collections at WDEQ/WQD

station WB220 (immediately

downstream of the Sage Creek

confluence) in 2004 indicated that

embedded riffles were present.

However, the riffle embeddedness

at WB220 was actually due to a thin

layer of fine sediment captured by

filamentous algae and aquatic

macrophytes. This thin fine sediment layer did not appear to fill or cover interstitial spaces and was

therefore not suggestive of excessive sedimentation. Absence of excessive sedimentation at WB220 was

further supported by the absence of newly-developed mid-channel and point bars and braiding. The

available physical data on the North Platte River is insufficient to detect temporal trends in

embeddedness or sedimentation below Sage Creek. However, it can be inferred from the data collected

at WB220 and other nearby stations that sediment reduction efforts in Sage Creek have reduced

anthropogenic sources of sedimentation to the North Platte River below Sage Creek.

In light of prior concerns on anthropogenic sediment loading to the North Platte River, there were no

indications of excessive sedimentation or erosion at recently monitored (post-2002) WDEQ/WQD stations

below Sage Creek or throughout the rest of the segment. Where applicable, all WDEQ/WQD stations

within this segment scored >85% of the mean percent of maximum habitat score for the reference sites

used for comparison. Streams with ≥75% comparability in habitat scores with reference conditions are

considered supportive of habitat requirements for aquatic life (Plafkin et al. 1989).

5.5 Aquatic Life Condition

(See Appendices 2-7 thru 2-13 for dataset) The condition of aquatic life, as evaluated with benthic

macroinvertebrates, was determined using two biological indicator models, the Wyoming Stream Integrity

Index (WSII) and the WY RIVPACS. The Wyoming Stream Integrity Index (WSII) is a regionally-

calibrated macroinvertebrate-based multimetric index designed to assess aquatic life use support in

Wyoming streams contained within seven bioregions (Hargett and Zumberge 2006). Bioregions are

defined as geographic regions that are relatively homogenous with regard to physical, chemical and

biological attributes. Index scores for WSII bioregions are calculated by averaging the standardized

values of various attributes or metrics (e.g. composition, structure, tolerance, functional guilds) derived

from a macroinvertebrate sample. Index scores for sites of unknown biological condition are then

compared to expected index scores from an appropriate set of regional reference sites that are minimally

WDEQ Station WB220 WDEQ/WQD Station WB220 (2004)

14

or least impacted by anthropogenic stress. The final output is an index score for each site where higher

scores that fall within the range of expected reference conditions imply high biological condition. Based

on numeric thresholds for each bioregion, index scores are codified into one of three narrative aquatic life

use-support categories of ‘full-support’, ‘indeterminate’, and ‘partial/non-support’. The indeterminate

category is technically not a use-support category, but rather a designation that requires the use of other

information to make a proper use-support assignment.

The Wyoming RIVPACS (River InVertebrate Prediction And Classification System) is a statewide

macroinvertebrate-based predictive model that assesses biological condition by comparing the

macroinvertebrate taxa observed at a site of unknown biological condition with the indigenous

macroinvertebrate taxa expected to occur in the absence of human stress (Hargett et al. 2007; Hargett et

al. 2005). The expected macroinvertebrate taxa are derived from an appropriate set of reference sites

that are minimally or least impacted by anthropogenic stress. The deviation of the observed from the

expected taxa, known as the O/E value, is a measure of the compositional similarity expressed in units of

taxa richness and thus a community level measure of biological condition. O/E values near 1 imply high

biological condition while values < 1 imply some degree of biological degradation. O/E values are

codified into one of three narrative aquatic life use-support categories where values >0.836 were

considered ‘full-support’, values between 0.662-0.836 are ‘indeterminate’ and values <0.662 are

‘partial/non-support’.

All sites, with the exception of SR12, were evaluated with the WSII developed for the Wyoming Basin

bioregion (Map 3). Site SR12 was evaluated with the WSII for the Southern Rockies bioregion (Map 3).

The WSII and WY RIVPACS indicated that most sites in North Platte River segment above Saratoga,

Wyoming were ‘fully-supportive’ of their aquatic life uses. Both models revealed that multi-year samples

collected immediately above (station SERCD1) and several miles below (station SERCD2) Sage Creek

showed a decline in biological condition from a ‘full-support/indeterminate’ status in 1999 to

‘indeterminate/partial or non-support’ in 2002 (Figure 2). Biological condition at station SERCD1

increased from 2002 to 2005. SERCD2 followed a similar pattern but experienced a small decline in

2005 according to the WSII and a substantial decline noted by the WY RIVPACS (Figure 2). Biological

condition at SERCD2 (located below Sage Creek) was generally higher compared to SERCD1 (upstream

of Sage Creek). The reason for this pattern is unknown. Situated between SERCD1 and SERCD2,

station WB220 was assigned an ‘indeterminate’ status by the WSII and ‘partial/non-support’ by WY

RIVPACS in 2004. Based on this and other information from these stations, it is believed that

consecutive years of drought, particularly in 2001 and 2002 (Figure 1), was the predominant stressor to

the macroinvertebrate community in the North Platte River resulting in the biological condition decline at

SERCD1 and SERCD2 from 1999 to 2002. Drought conditions can severely reduce flows resulting in

impacts to the invertebrate populations through a reduction in aquatic habitat and increase environmental

15

stressors such as elevated water temperature, oxygen deficits, lower velocities and temporary

sedimentation or embeddedness of riffles (Ward 1992). Drought conditions were prevalent in 2004

though near to above average stream flows in 2003 and 2005 may have offset impacts to the

macroinvertebrate community from this single low water year as evidenced by the general improving

biological condition during these years. Excess sediment from Sage Creek possibly contributed to the

decline in biological condition of the North Platte River below Sage Creek from 1999 to 2002.

The decline in biological condition in 2005 at SERCD2 is believed to be due to a large precipitation event

in the Sage Creek watershed (anecdotal information suggests a 1 in 50 year event) a few weeks prior to

sampling. This precipitation event resulted in scouring of a large amount of sediment (both natural and

anthropogenic-related) that had accumulated in Sage Creek for many years that was subsequently

deposited in the North Platte River at and within the vicinity of SERCD2 (SERCD, personal

communications).

The general positive trend in biological condition at the SERCD stations since 2002 likely reflects the

improving precipitation and flow conditions during this period. Though data are limited, it is also assumed

that BMP efforts in Sage Creek and at its confluence with the North Platte River also contributed to this

general positive trend through improvements in aquatic habitat. Overall, the positive trend in biological

condition since 2002 suggests the North Platte River both immediately above and below Sage Creek will

continue to show improvement as the aquatic community rebounds from the lingering effects of the

drought and BMP efforts in the Sage Creek watershed continue to reduce anthropogenic sediment

loading.

Farther downstream from Sage Creek,

station WB174 received an ‘indeterminate’

status from the WSII and a ‘partial/non-

support’ status from WY RIVPACS.

Conditions at this station are believed to be

principally due to environmental stressors

related to drought conditions during and

prior to the September 2002 sampling.

Flows at this station in 2001 and 2002 were

well below normal based on the 67-year

record at USGS station 0663000 (Figure 1).

WDEQ/WQD Station WB174 (2002)

16

Map 3 – The North Platte River watershed with bioregions and associated monitoring stations. Red dots represent WDEQ stations where chemical, physical and biological data were collected, yellow dots represent water-quality only WDEQ stations, green dots represent USGS fixed stations and gray dots represent SERCD stations.

17

Figure 2 – WY RIVAPCS and WSII biological condition scores for stations SERCD1 and SERCD2 in the Wyoming Basin bioregion and associated numeric aquatic life-use thresholds.

00.10.20.30.40.50.60.70.80.9

1

1999 2000 2001 2002 2003 2004 2005

WY

RIV

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Sco

re

SERCD1 SERCD2

Full-Support Threshold Indeterminate Threshold

0

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1999 2000 2001 2002 2003 2004 2005

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18

6.0 SEGMENT 2 – SEMINOE RESERVOIR TO CASPER, WY


Segment 2 receives inflows from Segment 1 and streams within the Seminoe-Pathfinder (HUC

10180003), Medicine Bow (HUC 10180004), Little Medicine Bow (HUC 10180005), Sweetwater (HUC

10180006) and Middle North Platte-Casper (HUC 10180007) sub-basins (Map 1). The watershed of this

segment is situated within four level III ecoregions: Middle Rockies, Northwestern Great Plains, Southern

Rockies and Wyoming Basin (Omernik and Gallant 1987) (Map 2). As with the Southern Rockies, the

Middle Rockies are characterized by coniferous forests, subalpine meadows and alpine tundra, though

represent a small percentage of the entire North Platte watershed. The Northwestern Great Plains is a

semi-arid mixed-grass prairie environment. Primary land uses along this segment are livestock grazing

and irrigated agriculture. This segment drains a watershed comprised largely of sedimentary formations

and marine shales common to the Wyoming Basin and Northwestern Great Plains with some granitics

and metamorphic materials in the mountains (USGS 1985). The North Platte River is considered a Class

1 water from the headwaters of Pathfinder Reservoir upstream to Kortes Dam and from Natrona County

Road 309 bridge (near the confluence with Poison Spider Creek) upstream to Alcova Dam (WDEQ/WQD

2007). The remainder of the segment, including all reservoirs, is considered Class 2AB (WDEQ/WQD

2007).


This segment is characterized

by a series of reservoir

tailwaters where flows are

stored and released for

irrigation projects, flood

control and hydropower

production (the following

information on reservoirs and

their operations within this

and all downstream segments

was obtained from

http://www.usbr.gov/). Five

storage facilities interspersed

along the North Platte River

are used by the United States

Bureau of Reclamation (USBOR) to satisfy these demands. Operation of these impoundments is

conducted to satisfy agreements and laws governing water rights along the North Platte River. These

operations result in release regimes that vary in time and magnitude among reservoirs.

0

1000

2000

3000

4000

5000

6000

7000

8000

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Mean Daily Discharge 1995-2005 Max Daily Discharge Min Daily Discharge

Figure 3 – Annual hydrograph (1995-2005) of mean daily releases from Kortes Dam.

19

Seminoe Reservoir provides up to 1,017,279 acre-feet of storage and captures inflows from Segment 1

and the Medicine Bow River. Water released from Seminoe Reservoir is used by the USBOR to generate

electricity from the 45,000-kilowatt Seminoe Powerplant located at the base of the dam. Immediately

downstream from Seminoe Dam, Kortes Reservoir provides storage for 4,765 acre-foot of water where

releases are operated in conjunction with Seminoe Reservoir to generate electricity from the 36,000-

kilowatt Kortes Powerplant located at the base of the dam. USBOR maintains releases from Kortes Dam

at a minimum of 500 cfs year-round (Figure 3) in accordance with Senate Bill 2553 passed in the 90th

Federal Congress. This bill authorized minimum releases of water from Kortes Dam to maintain the blue-

ribbon trout fishery in the stretch of the North Platte River between Kortes Dam and Pathfinder Reservoir,

commonly referred to as the Miracle Mile. During the irrigation season, additional water is released from

the reservoirs for downstream irrigation needs.

Flows from the Miracle Mile segment are joined with those from the Sweetwater River in Pathfinder

Reservoir, which has a storage capacity of 1,016,000 acre-feet. During the non-irrigation season,

releases from the dam satisfy downstream water rights, enhance fish and wildlife and operate the 66,800-

kilowatt Fremont Canyon and

the 36,000-kilowatt Alcova Dam

powerplants. Below Pathfinder

Dam, a 3-mile long tunnel

diverts water to generate

electricity at the Fremont

Canyon Powerplant. This water

is eventually released back to

the river upstream of Alcova

Reservoir. Releases from

Pathfinder Dam are erratic, but

generally peak in June and July

during the irrigation season and

are at their lowest in October

(Figure 4). Downstream, Alcova

Reservoir stores up to 184,405 acre-feet of water, some of which is diverted into nearby Casper Canal to

irrigate lands in the USBOR Kendrick Project area. Additional water is released for other downstream

irrigation rights as needed.

The Kendrick Project area (formally known as the Casper-Alcova Project) consists of 24,000 acres of

irrigable project lands that lie on the northwest side of the North Platte River between Alcova Dam and

Fremont Canyon

0

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3000

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6000

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Figure 4 – Annual hydrograph (1995-2005) of mean daily releases from Pathfinder Dam.

20

Casper, Wyoming (Map 1). The irrigation distribution system for the Kendrick Project area consists of the

59 mile long Casper Canal, 190 miles of laterals and sublaterals, and 41 miles of drains. The main canal

has a capacity of 1,200 cfs. Principal crops in the Kendrick Project are alfalfa, small grains and irrigated

pasture.

Gray Reef Reservoir is located

approximately two miles

downstream of Alcova Dam and

has a capacity of 1,800 acre-

feet. The USBOR operates the

reservoir primarily to re-regulate

flows as a result of widely

fluctuating releases through the

Alcova Powerplant. Releases

from Gray Reef Dam are

ramped up during the irrigation

season and generally peak in

June and July (Figure 5).

Periodically in the spring, the

USBOR releases a series of

fluctuating flows from Gray Reef Dam at the request of the WGFD to improve trout habitat by flushing fine

sediment from spawning gravels.

Though inflows from the two major tributaries in this segment (i.e. Medicine Bow River and the

Sweetwater River) are regulated within impoundments, the North Platte River also receives direct inputs

from secondary tributaries, particularly downstream of Gray Reef Reservoir. These tributaries include

Bates Creek, Casper Creek and Poison Spider Creek. Bates Creek is a perennial to intermittent stream

that drains erodible sedimentary materials of the Wyoming Basin and flows generally originate from

springs and seeps. Inflows from Casper Creek, Poison Spider Creek and other tributaries on the west

side of the North Platte River in the Kendrick Project area, are essentially North Platte River water

conveyed through drains, return flow ditches and seepage from irrigated fields. Effluent from oil treater

discharges and natural springs constitute a small percentage of inflows from these streams. Other

streams tributary to this segment of the North Platte River generally have their origins in the Wyoming

Basin and are intermittent to ephemeral.

Water quality in a reservoir tailwater typically reflects near steady-state conditions though may change

periodically due to conditions in the upstream reservoir(s) and flow releases. The reservoirs on the North

0

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Figure 5 – Annual hydrograph (1995-2005) of mean daily releases from Gray Reef Dam.

21

Platte River release hypolimnetic water where constituents such as temperature, dissolved oxygen and

nutrients may fluctuate due to the level of dilution from mid-depth and surface water. This is in contrast to

the dynamic fluctuations in physicochemical conditions (i.e. extremes in turbidity, temperature, suspended

sediment, dissolved oxygen) that are expected for streams and rivers that drain areas of the Wyoming

Basin. Point and non-point sources also contribute to the water quality of North Platte River in segment

2. The most common permitted point source discharges to this segment of the North Platte River are oil

treaters via Casper Creek, Poison Spider Creek and other tributaries. Water quality of the North Platte

River downstream of Gray Reef Reservoir is greatly influenced by irrigation activities in the Kendrick

Project area. Soils in this area contain naturally high levels of selenium, which is readily dissolved and

transported by irrigation water. As a result, irrigation return flows from this area contain high

concentrations of selenium which results in selenium loading to the North Platte River. These loadings

have resulted in numerous water quality standards exceedences for streams that include the North Platte

River, Casper Creek and Poison Spider Creek. These and other waters in the Kendrick area are

currently listed by WDEQ/WQD on Table A of the State of Wyoming’s 303(d) list. The reach of the North

Platte River impaired for selenium exceedences extends an undetermined distance upstream and

downstream of Casper, Wyoming. The Natrona County Conservation District in cooperation with other

local groups are currently developing water quality management plans to address the selenium loading to

the North Platte River.


(See Appendix 3-1 for dataset) Water temperatures in this segment of the North Platte River on the dates

of sampling were below the WDEQ/WQD (2007) maximum criteria of 20◦C for a cold-water fishery.

Throughout the segment, dissolved oxygen

concentrations were above the acceptable

one-day minimum criterion of 8 mg/L that is

considered protective of early aquatic life

stages in Class 1 and 2AB waters

(WDEQ/WQD 2007). Turbulent reservoir

releases combined with dense beds of

aquatic vegetation resulted in super-

saturated dissolved oxygen concentrations

>10 mg/L at some sites. Temperature and

dissolved oxygen concentrations at these

sites may vary depending on upstream reservoir conditions. All pH values throughout the segment, with

the exception of station WB175, were within the limit of 6.0-9.0 (WDEQ/WQD 2007). The pH at WB175

was >9.0, which was probably the result of elevated photosynthetic rates from the thick stands of aquatic

macrophytes on the channel bed.

WDEQ Station WB175


22

Recent guidance by the USEPA (2000b) recommends maximum total phosphorous and nitrate-nitrogen

concentrations of 0.022 mg/L and 0.025 mg/L, respectively, to protect aquatic life uses for streams in the

Wyoming Basin ecoregion. Concentrations

of these nutrients at most stations were

below detection (<0.1 mg/L), though this

information is not particularly informative

since the detection limit was greater than the

recommended concentration. However, the

presence of thick aquatic macrophyte stands

in the North Platte River below the

reservoirs suggests nutrient enrichment may

be occurring at lower concentrations. This is

expected since hypolimnetic reservoir

releases can contain nutrients that when

oxidized, become bioavailable. For

example, station WB181 exhibited a nitrate-nitrogen concentration of 0.1 mg/L that exceeded the

recommended maximum concentration for the Wyoming Basin. The source of this nutrient was likely

hypolimnetic water releases from Pathfinder Dam, located immediately upstream.

Conductivity, sulfate, alkalinity and hardness generally increased with distance downstream due to the

influence of dissolved solids conveyed in streams that drain the carbonate sedimentary materials in the

Wyoming Basin and to the cumulative effects of evapo-concentration in reservoirs. All measured chloride

concentrations were below the 230 mg/L criterion protective of aquatic life uses (WDEQ/WQD 2007).

Because metals were listed as a possible source of impairment in the North Platte River below Alcova

Dam in the State of Wyoming’s 1996 303(d) list; total selenium, total copper, total cadmium, total lead

and/or total mercury were collected at stations WB179, WB176, WB177, and WB178. With the exception

of total selenium at station WB176, concentrations of all metals at all sites were below reporting

detectable limits. The total selenium concentration of 6 ug/L at station WB176 exceeded the in-stream

chronic criterion of 5 ug/L considered protective of aquatic life uses (WDEQ/WQD 2007). Sources of the

selenium were likely irrigation return flows to the North Platte River from the Kendrick Project area.


(See Appendix 3-2 for dataset) Habitat conditions for three sites (i.e. WB175, WB181 and WB176) within

this North Platte River segment were evaluated with the use of the large river qualitative habitat


23

assessment procedure (WDEQ/WQD 2004). Total habitat scores could not be compared to a reference

condition since one has not been developed for this portion of the North Platte River.

In general, streambanks along this segment were considered stable with adequate riparian vegetation

and coarse material to protect the banks and minimize erosion during high flows. The riparian area at

station WB176 appeared to receive heavy

grazing pressure, but otherwise, banks

were stable. Bed substrate in this

segment is largely cobble and gravel and

was slightly embedded or relatively free of

fine sediment covering/surrounding the

particles. This is most likely due to

periodic reservoir releases that flush fines

from the channel bed. Riffles were

infrequent at station WB181 which

lowered the overall habitat score for this

station. Except for the short reach where WB181 was located, the channel below Pathfinder Dam

downstream into Fremont Canyon is geologically confined by bedrock. Due to the confinement, the

bedrock channel and canyon walls, rather than typical riffles, function to dissipate most energy in this

reach. The few cobble riffles that are present near WB181 occur in the relatively short ‘unconfined’

sections of the channel where the river has a chance to access a typical alluvial floodplain. At all three

stations, there were no indications of excessive sedimentation or erosion to the river. However, an un-

vegetated sediment delta with recent accumulations of silt and sand was observed in the North Platte

River at the confluence with Bates Creek upstream of station WB176.


(See Appendices 2-10, 3-3, and 3-4 for dataset) Though both the WSII and WY RIVPACS provide a

framework for assessment of biological condition, neither model was specifically designed to assess

biological condition for reservoir tailwaters or large river environments such as the North Platte River

downstream of Kortes Dam. Consequently, without a known biological benchmark for these types of

systems, determinations of aquatic life use support from these models may not be representative for this

and all downstream North Platte River segments. In lieu of making a use-support determination, model

results were used to look at spatial changes in assemblages along with why particular assemblages may

exist in different reaches of the North Platte River. Furthermore, the model results and macroinvertebrate

data can be used as “baseline” information for comparisons with future samples to look at temporal trends

in biological condition.

Fremont Canyon

Fremont Canyon


24

Both the WSII and WY RIVPACS assigned a ‘partial/non-support’ aquatic life use designation to stations

WB175, WB181 and WB176. The biological condition in reservoir tailwaters is expected to be quite

different and commonly lower compared to the unregulated reference streams from which the WSII and

WY RIVPACS were developed. The lower biological condition at these sites is primarily due to the effects

of reservoir releases on aquatic biota and tailwater ecology. This is due to the multiple cascading effects

of reservoirs on all aspects of river ecological structure and function such as altered sediment transport

and temperature regimes, reduced production, habitat alteration, and changes in biotic assemblages

which include fewer native taxa and more nonnative taxa with increased densities of the tolerant taxa

present (Nestler et al. 1986, Petts 1984, Poff et al. 1997, Stanford et al. 1996, Walburg et al. 1980 and

1981, and Ward and Stanford 1995). Ephemeroptera, Trichoptera, and Plecoptera taxa richness for the

three bioassessment stations in this segment were below reference conditions, though as expected,

densities for one or more of these groups (which included mostly tolerant taxa) were high. Decreased

richness may be due to fluctuations in chemical conditions of the tailwater (as discussed previously)

and/or physical dislodgement from the substrate (Anderson and Lehmkuhl 1968), stranding (Trotzky and

Gregory 1974) or changes in daily flow cycles (Perry and Perry 1986). These communities may be

dominated by chironomids, dipterans, oligochaetes, amphipods, and a few tolerant taxa from each of the

Ephemeroptera, Trichoptera and Plecoptera. Chironomids and dipterans and a few mayfly and caddisfly

taxa comprised a large percentage of the total number of individuals in the macroinvertebrate

communities at these three stations. Tailwaters can also be represented by a macroinvertebrate

community dominated by filter-feeding or collector-gatherer taxa (Nestler et al. 1986) due to abundant

quantities of particulate organic matter in reservoir releases. Stations on the North Platte River

exemplified this condition where >70% of the community at station WB175 were collector-gatherers and

>60% of the community at WB181 were filter-feeders. Though situated at a greater distance downstream

from the reservoirs, station WB176 also exhibited large percentages of these two functional feeding

groups.

There is also a possibility that selenium loading from the Kendrick Project area contributes to the lower

biological condition at station WB176. The total selenium concentration at WB176 exceeded the chronic

aquatic life criterion of 5 ug/L (WDEQ/WQD 2007). The 5 ug/L criterion was designed to protect against

mortality, reproductive interferences and growth abnormalities in fish and other aquatic organisms due to

long-term exposure to selenium in the aquatic food chain. The USEPA indicates selenium toxicity to fish

and other aquatic life primarily results from accumulation of selenium in sediment, movement into the

food chain and resulting dietary uptake rather than from direct exposure to selenium in the water.

Available literature on the mechanisms and effects of selenium toxicity to benthic macroinvertebrates is

very limited. At this time, it is unknown whether bed sediments in the North Platte River at WB176

contain high selenium concentrations and if present, are impacting the benthic macroinvertebrate

community via dietary pathways. However, if it is found that the benthic macroinvertebrate community is

25

impacted by selenium toxicity, it may be difficult to discern the degree of impact from selenium toxicity in

light of the effects of reservoir operations on the flows and habitat availability in the system.

26

7.0 SEGMENT 3 – CASPER, WY TO GLENDO RESERVOIR


Segment 3 receives inflows from Segment 2 and streams within the Middle North Platte-Casper (HUC

10180007) and Glendo Reservoir (HUC 10180008) sub-basins (Map 1). The watershed of this segment

is situated within two level III ecoregions: Northwestern Great Plains and Southern Rockies (Omernik and

Gallant 1987) (Map 2). Primary land uses along this segment are livestock grazing and irrigated

agriculture. This segment is comprised of sandstone, limestone and siltstone formations north of the river

in the Northwestern Great Plains, and granitics and sedimentary deposits in the Southern Rockies to the

south (USGS 1985). The North Platte River is classified as a Class 2AB water (WDEQ/WQD 2007).


Flows in this segment are dependent on upstream reservoir releases conveyed downstream to satisfy

water right demands between Casper and Glendo Reservoir and for storage in Glendo and Guernsey

Reservoirs. Mean daily streamflow statistics for USGS station 06652000 (North Platte River at Orin,

Wyoming) show the effects of flow regulation in the variability in streamflows during the summer months

with flows greatest in June and

July during the peak irrigation

season (Figure 6). There are no

major dams on this segment

other than the diversion

structure that supplies water to

the Dave Johnson Powerplant

near Glenrock, Wyoming and

several direct withdrawals of

water for irrigation uses.

Tributaries to this segment

include Boxelder Creek, Deer

Creek, LaBonte Creek, LaPrele

Creek, Muddy Creek and

Wagonhound Creek. These are

spring-fed streams that originate

in the Laramie Range. Flows of

these tributaries are affected by on-stream impoundments and/or irrigation diversions within their

watersheds. Tributaries that drain areas north of the North Platte River are generally intermittent to

ephemeral.

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Figure 6 – Annual hydrograph (1950-2005) of mean daily streamflow at USGS station 06652000 (North Platte River at Orin, Wyoming).

27

Similar to Segment 2, the water quality in this segment typically reflects conditions in releases from the

upstream reservoirs and at least in the upper reaches, non-point source selenium loading from the

Kendrick Project area. However, water quality conditions can change in response to fluctuations in flow

from reservoir releases and irrigation diversions along the segment. Permitted discharges along the

segment include the wastewater treatment plants and stormwater facilities of Casper, Glenrock and

Douglas; oil treaters; product water from the Casper Refinery and flow-through water from the Dave

Johnson Powerplant. These discharges may result in localized changes to water quality of the North

Platte River.


(See Appendix 4-1 for dataset) Water temperatures on the dates of sampling were below the

WDEQ/WQD (2007) maximum criteria of 20◦C for a cold-water fishery, though criteria may be exceeded

during the summer months. Throughout the segment, dissolved oxygen concentrations were above the

acceptable one-day minimum criterion of 8 mg/L that is considered protective of early aquatic life stages

in Class 2AB waters (WDEQ/WQD 2007). Dissolved oxygen concentrations can fall below 8 mg/L during

the summer low-flow months when demands on the river are at their peak. All pH values throughout the

segment were within the limit of 6.0-9.0 (WDEQ/WQD 2007).

Recent guidance by the USEPA (2001a) recommends maximum total phosphorous and nitrate-nitrogen

concentrations of 0.029 mg/L and 0.030 mg/L, respectively, for protection of aquatic life uses for streams

in the Northwestern Great Plains ecoregion. Concentrations of these nutrients at station NGP193 were

below detection (<0.1 mg/L)

though this information is not

particularly informative since the

detection limit was greater than

the recommended nutrient

reference conditions. However,

filamentous algae was common at

this site which may be evidence of

nutrient enrichment at lower concentrations. Nutrients were not analyzed at the CASPER1 and

CASPER2 stations, though dense stands of filamentous algae were common at both stations on the

dates of sampling, again suggestive of nutrient enrichment. Most nitrate-nitrogen samples at USGS

stations 06645000 (North Platte River below Casper, Wyoming) and 06652000 exceeded the

recommended maximum concentration. A single sample collected at USGS station 06652000 exceeded

the recommended maximum concentration for total phosphorous. Sources of these nutrients are likely

anthropogenic and may include non-point source runoff and groundwater contributions from agricultural

WDEQ/WQD Station CASPER2 (2003)

28

lands, malfunctioning septic systems and reservoir releases of nutrient-rich hypolimnetic water,

stormwater runoff and effluent from wastewater treatment facilities.

Sulfate, alkalinity and hardness were elevated and conductivity increased with distance downstream.

This was largely due to the influence of naturally elevated concentrations of dissolved solids conveyed in

streams that drain the carbonate sedimentary materials in the Wyoming Basin and Northwestern Great

Plains, effects of evapo-concentration due to irrigation and reservoir operations, and a general increase in

watershed area. Chloride concentrations were all below the 230 mg/L criterion protective of aquatic life

uses (WDEQ/WQD 2007).

Several samples collected at USGS station 06645000 exceeded the 5 ug/L total selenium criterion that is

protective for aquatic life uses (WDEQ/WQD 2007). Sources of selenium were likely irrigation return

flows to the North Platte River from the Kendrick Project and other areas where soils are naturally

elevated in selenium. Dissolved arsenic concentrations in samples collected from this same USGS

station were below the maximum human health, fish consumption and drinking water criterion of 10 ug/L

(WDEQ/WQD 2007). Similarly, all dissolved concentrations of zinc, lead, copper, and cadmium were

below the hardness-dependent aquatic life use chronic criteria of 249.8, 6.5, 19.1, and 4.3 ug/L,

respectively (WDEQ/WQD 2007)2.

All fecal coliform concentrations from samples collected at the North Platte River below Casper, Wyoming

(USGS station 06645000) and the North Platte River at Orin, Wyoming (USGS station 06652000), from

April 1 to October 31, were below the single-sample maximum E. coli concentration of 235 col/100 mL for

high use swimming areas on waters designated for primary contact recreation (WDEQ/WQD 2007).

However, fecal coliform concentrations in the North Platte River below the Casper wastewater treatment

facility exceeded this criterion on the date of sampling. Because E. coli are a subset of fecal coliform

bacteria, it is scientifically acceptable, in this circumstance, to conclude that when the fecal coliform

concentration in a sample is less than the E. coli criteria, then the concentration of E. coli in the same

sample is also less than the E. coli criteria. Conversely, if the fecal coliform concentration in a sample

exceeds the E. coli criteria, then the E. coli concentration in the same sample is also assumed to exceed

the criteria.


(See Appendix 4-2 for dataset) Habitat condition for station NGP193 was evaluated with the large river

qualitative habitat assessment procedure (WDEQ/WQD 2004). The total habitat score for this station was

2 The aquatic life use chronic criteria for metals were calculated with a mean hardness concentration of 242 mg/L derived from 1967-1983 data. This was done because hardness, calcium and other cations were not analyzed concurrently with the metals samples collected in the late 1990s to present.

29

not compared to a reference condition since one has not been identified for this portion of the North Platte

River.

Streambanks at station NGP193 were considered stable with adequate riparian vegetation and coarse

material to protect the banks and minimize erosion during high flows. Bed substrate at this station was a

combination of gravel and sand.

The coarse particles were

considered embedded or

covered/surrounded by fine

sediment. The embedded

substrate appeared to partially

result from sediment capture from

macrophytes and filamentous algae, though is also suspected to be due to a reduction in natural

sediment transport due to low flows from upstream reservoir operations and diversions. Upstream

irrigation return flows and stormwater drains from the cities of Casper and Douglas may also contribute

fine sediment to the system. Newly deposited mid-channel and point gravel bars were present upstream

and downstream of the site, suggesting sedimentation is occurring.


(See Appendices 2-10, 4-3 and 4-4 for dataset) Biological condition at station NGP193 was evaluated

with the WSII developed for the Plains bioregion (Map 3) and WY RIVPACS. However, as stated

previously for Segment 2, these results should be used with caution since neither model was designed to

assess biological condition for large flow-regulated river segments of the North Platte River. Model

results should be used as “baseline” information for future sample comparisons. NGP193 received a ‘full-

support’ from the WSII while WY RIVPACS assigned a ‘partial/non-support’ for aquatic life use support.

Recent studies indicate that disagreement between biological indicators such as multimetric and

predictive models is not uncommon (Hawkins 2006). Disagreement in biological condition likely arises

from differences in both the biological and statistical properties of the models. Indicators that utilize

macroinvertebrate metrics could be either more or less responsive to stressors affecting a site than

changes in taxa richness. Hawkins (2006) found that predictive models were more likely to accurately

detect anthropogenic disturbance than multimetric models because of the greater precision and sensitivity

to stressors at the sample station. However, multimetric models may provide insightful information on

specific environmental stressors that influence the macroinvertebrate assemblage.

It can be inferred from just the hydrologic modifications to the system that the potential for extremes in

physicochemical conditions exists and that a low biological condition could be expected at NGP193. The

WY RIVPACS determined that given the river’s reach and watershed characteristics, the

WDEQ/WQD Station NGP193 (2004)

30

macroinvertebrate assemblage at NGP193 had diminished richness of native taxa (i.e., specific genera

and species) that would be expected in the absence of human disturbance, hence the ‘partial/non-

support’ assignment. The macroinvertebrate assemblage at NGP193 was comprised of wide-spread,

generalist taxa such as Chironomids, non-insects and a few Ephemeroptera (Baetis and Tricorythodes)

and Trichoptera (Cheumatopsyche, Hydropsyche and Hydroptila) that are tolerant to a wide-range of

environmental conditions (i.e. migrating habitat features, variable flows, extreme temperatures, and low

dissolved oxygen).

Conversely, the WSII indicated full-support of biological condition at NGP193. The high rating was largely

driven by favorable scores in the Ephemeroptera, Trichoptera and Total Taxa richness metrics. It is

suspected that these favorable metric values were influenced by at least two factors. First, species

richness can increase with moderate levels of nutrient enrichment. Considering that nutrient

concentrations in this segment exceed the federally recommended criteria for plains streams, this may be

one possible explanation for the elevated metric values. Second and perhaps of more importance, large

river systems, because of their size and greater habitat complexity, may naturally support greater

biological diversity in benthic macroinvertebrates (i.e., taxa richness) relative to smaller streams.

Considering that it is well accepted in the literature that large rivers support a greater diversity of fishes

compared to smaller streams, the same likely holds true for macroinvertebrates. The higher diversity

could be the result of greater availability and diversity in habitat types (i.e., main channel, side channel,

backwater, and shoreline) and dispersal and immigration of taxa from numerous tributaries and aquatic

habitats, to name a few.

Though the number of taxa for the Ephemeroptera, Trichoptera and Total Taxa groups was comparable

to reference conditions, the WSII does not consider the genera or species that contribute to the richness

values for these groups like the WY RIVPACS. This is important because the aquatic community may

have the same number of taxa, but the indigenous taxa adapted to the natural condition were replaced by

those better able to exploit a human manipulated condition. This can contribute to disagreement between

the WY RIVPACS and WSII.

Values of ‘Percent Trichoptera (less Hydropsychidae - % within community)’ and ‘Percent Ephemeroptera

(less Baetidae - % within community)’, which remove most generalist taxa, and ‘Percent collector-

gatherers’ and ‘HBI’, all suggest the benthic macroinvertebrate community at NGP193 is stressed. The

high density of collector-gatherers in the community represents another line of evidence that nutrient

enrichment may be present. In addition, a large percentage of non-insects (54%) (of which the majority

were aquatic worms) and a sizeable proportion of chironomids (19%) comprised the benthic

macroinvertebrate community. The dominance of non-insects and chironomids occurs in large rivers or

31

streams with sedimentation, embedded substrates, harsh physicochemical conditions and/or significant

pollution such as nutrient enrichment (Thorp and Covich 2001).

The available biological evidence suggests the benthic macroinvertebrate community at NGP193 is

limited, likely due to flow regulation and resultant changes in physicochemical and habitat conditions,

sedimentation and possible nutrient enrichment. However, because of the discrepancies in model results

combined with their limitations in assessment of large flow-regulated river segments, the absence of an

appropriate reference condition for these systems, and the limited number of biological samples collected

on this segment, it is difficult to make a conclusive determination on the degree to which the North Platte

River in Segment 3 is limited in its ability to support aquatic life uses.

32

8.0 SEGMENT 4 – GLENDO RESERVOIR TO WY/NE STATELINE


Accounting for inflows from Segment 3, the watershed that drains Segment 4 is comprised of streams

from the Glendo Reservoir (HUC 10180008), Middle North Platte-Scottsbluff (HUC 10180009), Upper

Laramie (HUC 10180010), Lower Laramie (HUC 10180011) and Horse Creek (HUC 1018012) sub-basins

(Map 1). The watershed of this segment is situated within three level III ecoregions: Northwestern Great

Plains, Southern Rockies and the Western High Plains (Omernik and Gallant 1987) (Map 2). Primary

land uses along this segment are livestock grazing, irrigated hay and crop production, oil and gas

development and sand/gravel mining. This segment is comprised primarily of sandstone, limestone and

siltstone formations in the Northwestern Great Plains and Western High Plains and granitics and

sedimentary deposits in the Southern Rockies (USGS 1985). The North Platte River in this segment is a

Class 2AB water (WDEQ/WQD 2007).


Flows in this segment are stored and released for irrigation, flood control and hydropower production in

Glendo and Guernsey Reservoirs. As with the reservoirs in Segment 2, operation of these two

impoundments is conducted by the USBOR and is dictated by agreements and laws governing water

rights including the amended North Platte River Decree of 1953 between Wyoming and Nebraska.

Administration of this decree is conducted through the exchange of water between Glendo and Guernsey

Reservoirs and the upstream reservoirs in Segment 2. The complex operation of river impoundments to

satisfy multiple needs results in release regimes that vary temporally and among reservoirs.

North Platte River inflows from

Segment 3 are stored in Glendo

Reservoir which provides up to

795,196 acre-feet of storage.

Space is also provided to store up to

115,000 acre-feet of sediment. An

estimated 454,337 acre-feet is

allotted for irrigation and power

production and 271,917 acre-feet for

flood control. The USBOR releases

water into tunnels from Glendo

Reservoir to generate electricity

from the 38,000-kilowatt Glendo

Powerplant located downstream of

the dam. In 1992, a low flow outlet was constructed to provide a minimum 25 cfs to maintain fisheries

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Figure 7 – Annual hydrograph (1995-2005) of mean daily releases from Guernsey Dam.

33

and wildlife habitat below the dam. Major tributaries to the North Platte River between Glendo and

Guernsey Reservoirs are Horseshoe Creek and Cottonwood Creek. Contributions from these tributaries

is minimal as water is diverted for irrigation prior to reaching the North Platte River. Twenty-five miles

downstream from Glendo Dam, Guernsey Reservoir provides storage for 46,000 acre-feet of water where

releases are used to generate electricity from the 6,400-kilowatt Guernsey Powerplant at the base of the

dam. During the irrigation season, the USBOR releases water as required from Glendo and Guernsey

Reservoirs to irrigate lands in the USBOR North Platte River Project area. Releases from Guernsey

Reservoir cease for about six months during the non-irrigation season (Figure 7).

The North Platte River Project area extends from Guernsey, Wyoming downstream 111 miles to

Bridgeport, Nebraska. The project provides irrigation water to 226,000 acres divided into four irrigation

districts. The irrigation distribution system for the North Platte Project area consists of 2,000 miles of

canals, laterals and drains. Principal crops in the area are alfalfa, small grains, irrigated pasture, sugar

beets and corn.

To irrigate lands in the North Platte River Project area, releases from Guernsey Reservoir are diverted at

the Whalen Diversion Dam near Fort Laramie, Wyoming (Map 1). River water is diverted to the north into

the Interstate Canal and to the south into the Fort Laramie Canal. The Interstate Canal extends for 95

miles along the north side of the North Platte River and has a capacity of 2,100 c.f.s. The Fort Laramie

Canal follows the south contour of the North Platte River valley for 129 miles and has a capacity of 1,500

c.f.s. Flows in the North Platte River below the Whalen Diversion Dam are dependent on releases from

Guernsey Reservoir and the amount of diversion into the Fort Laramie and Interstate Canals.

Downstream of Guernsey Dam, the

North Platte River receives inputs

from two major tributaries: the

Laramie River (via releases from

Grayrocks Reservoir) and Rawhide

Creek. Most flows from the Laramie

River are diverted or stored for

irrigation purposes prior to reaching

the North Platte River. Flows in

Rawhide Creek consist of water

primarily from irrigation return flows

and drains and seepage from

irrigated fields. During the non-

irrigation season, the Laramie River

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Figure 8 – Annual hydrograph (1928-2005) of mean daily streamflow at USGS station 06674500 (North Platte River at WY/NE Stateline).

34

provides most of the flow in the North Platte River below Guernsey Dam. Most other tributaries to the

segment are ephemeral to intermittent. Effluent from permitted municipal wastewater treatment facilities

also provide flows to the North Platte River. Near the Wyoming/Nebraska stateline, tributaries, irrigation

return flows and point source discharges tend to result in a less-dynamic hydrograph (Figure 8) compared

to that at Guernsey Dam (Figure 7).

The North Platte River below Guernsey Dam experiences the annual Guernsey ‘silt run’, an exception to

the State’s turbidity criteria (WDEQ/WQD 2007). The practice removes accumulated sediment from

Guernsey Reservoir and seals downstream irrigation canals to minimize their transit losses. The annual

complete drawdown of Guernsey Reservoir commences in early July and extends for several days.

During that time, in-stream turbidity is elevated and a substantial amount of sediment enters the canals

and the North Platte River directly and via returns. Non-point sources such as irrigation return flows may

also alter water quality through elevated sediment contributions and nutrient enrichment. Permitted

discharges from municipal wastewater treatment facilities can also result in localized changes to water

quality in this segment.


(See Appendix 5-1 for dataset) Water temperatures on the dates of sampling were generally below the

WDEQ/WQD (2007) maximum criteria of 20◦C for a cold-water fishery. However, water temperatures can

exceed 20◦C in reaches below Guernsey Reservoir during summer low flow periods when much of the

river is diverted for irrigation and warm irrigation return flows enter the river. Throughout the segment,

dissolved oxygen concentrations for the majority of samples were above the acceptable one-day

minimum criterion of 8 mg/L that is considered protective of early aquatic life stages in Class 2AB waters

(WDEQ/WQD 2007). Dissolved oxygen concentrations can fall below 8 mg/L during the summer low-flow

months when demands on the river are at their peak. All pH values throughout the segment were within

the limit of 6.0-9.0 (WDEQ/WQD 2007).

Recent guidance by the USEPA (2001a)

recommends maximum total phosphorous

and nitrate-nitrogen concentrations of

0.029 mg/L and 0.030 mg/L, respectively,

for protection of aquatic life uses for

streams in the Northwestern Great Plains

ecoregion. Federally recommended

maximum concentrations of 0.06 mg/L and

0.72 mg/L for total phosphorous and

nitrate-nitrogen, are considered protective WDEQ/WQD Station NGP151 (2002)

35

of aquatic life uses in the Western High Plains ecoregion (USEPA 2001b). Concentrations of total

phosphorous at most stations were below detection (<0.1 mg/L), though this information is not particularly

informative since the detection limit was greater than the recommended concentration. Nitrate-nitrogen

ranged from 0.1 mg/L to 1.2 mg/L. The median for nitrate-nitrogen samples collected at USGS station

06674500 (North Platte River at WY/NE Stateline) was 2.0 mg/L. Nitrate-nitrogen concentrations at most

stations in the Western High Plains and at USGS station 06674500 exceeded the federally recommended

maximum concentration. A single sample collected at USGS station 06674500 exceeded the

recommended maximum concentration for total phosphorous. Total ammonia was not detected (<0.1

mg/L) in samples collected immediately above and below the City of Torrington wastewater treatment

facility. Indicators of nutrient enrichment included the presence of filamentous algae at most stations in

this segment with the greatest densities observed below Glendo Dam and downstream of the Torrington

wastewater treatment facility. Sources of nutrients are likely anthropogenic and include non-point source

runoff and groundwater contributions from agricultural lands, nutrient-rich reservoir releases,

malfunctioning septic systems and wastewater treatment facility discharges.

Sulfate, alkalinity, hardness, and conductivity were elevated due to naturally high concentrations of

dissolved solids conveyed in streams that drain the carbonate sedimentary materials in the plains, effects

of evapoconcentration due to diversions and reservoir operations, and a general increase in watershed

area. Discharge from the Torrington wastewater treatment facility can elevate alkalinity and sulfate in the

river immediately downstream from the discharge location. TSS increased with distance downstream, in

part due to sediment from irrigation return flows. Chloride concentrations were all below the 230 mg/L

criterion protective of aquatic life uses (WDEQ/WQD 2007). Concentrations of total selenium and total

arsenic above and below the Torrington wastewater treatment facility were non-detect (<5 ug/L).

The 5-sample/30-day geometric means for fecal coliform concentrations in samples collected immediately

above and below the Torrington wastewater treatment facility were below the criterion of 126 col/100 mL

on waters designated for primary contact recreation (WDEQ/WQD 2007). Because E. coli are a subset of

fecal coliform bacteria, it is scientifically acceptable, in this circumstance, to conclude that when the

geometric mean fecal coliform concentration in a sample is less than the geometric mean E. coli criterion,

then the geometric mean concentration of E. coli in the same sample is also less than the E. coli criterion.


(See Appendix 5-2 for dataset) Habitat condition for most stations within this segment was evaluated with

the large river qualitative habitat assessment procedure (WDEQ/WQD 2004). The total habitat scores for

these stations were not compared to a reference condition since one has not been identified for this

portion of the North Platte River.

36

Streambank stability and vegetation/coarse material protection varied throughout the segment. Banks

above Guernsey Reservoir were considered stable with adequate riparian vegetation. Generally, banks

downstream of Guernsey Dam were considered moderate to highly unstable with large percentages of

bank susceptible to erosion and sloughing during high flows. Bank armoring with concrete rip-rap,

abandoned vehicles and other material were common downstream of Guernsey Dam. Vegetation/coarse

material protection along these banks was less than optimal with areas of bare soil, close cropped

vegetation and species of riparian

vegetation with inadequate root mass

to maintain bank integrity. Much of

the channel substrate downstream of

Guernsey Dam consisted of mobile

sand overlain by unembedded gravel

bars which constitute the riffles in the

segment. Sediment deposition is

prevalent in the channel downstream

of Guernsey Dam with large expanses

of newly developed point and mid-channel bars. Sediment deposition in the river is likely due to loss of

sediment carrying capacity from withdrawal of a large percentage of the river for irrigation and reservoir-

controlled low flows during the non-irrigation season, sediment contributions during the annual Guernsey

‘silt run’ and from irrigation return flows. Fluctuations in reservoir releases have also caused changes in

channel morphology and contributed to sediment deposition. The variable reservoir-controlled high flows

increase near-bank stress, resulting in scour, bank erosion and ultimately deposition, thereby

compounding sedimentation of the channel. Land use practices may also contribute to the marginal bank

stability and sediment deposition in some reaches. Municipal stormwater drains may also contribute

sediment to the river. A depositional environment also occurs immediately upstream of Guernsey

Reservoir where a combination of sediment in water released from Glendo Dam and controlled flows

facilitate sediment deposition with a channel composed of mobile sand overlain by gravel.


(See Appendices 2-10, 5-3 and 5-4 for dataset) Stations within this segment were evaluated with the

WSII developed for the Plains bioregion (Map 3) and the WY RIVPACS. As stated previously for

Segments 2 and 3, results from these models should be used as “baseline” information rather than

conclusive determinations of aquatic life-use support since they are limited in their ability to accurately

assess biological condition for large, reservoir-controlled river segments of the North Platte River. Similar

to station NGP193 in Segment 3, discrepancies existed in biological condition assignments from the two

models for stations in Segment 4. The WSII assigned all stations a ‘full-support’ aquatic life use status

though index scores were lowest at NGP151, WHP36, WHP34 and WHP33. Stations WHP36, WHP33

WDEQ/WQD Station WHP32 (2002)

37

and WHP32 were assigned a ‘partial/non-support’ status by the WY RIVPACS. The WY RIVPACS

assigned an ‘indeterminate’ status to the remaining stations. Reasons for discrepancies in model output

scores for these stations are similar to those explained in the aquatic life condition discussion for

Segment 3.

Collectively, the evidence of channel degradation, sediment deposition and potential for extremes in

physicochemical conditions, as a result of hydrologic modifications in the system, suggest that a low

biological condition would be expected for Segment 4. Similar to Segment 3, Segment 4 stations were

generally comprised of wide-spread, generalist taxa such as Chironomids, non-insects and a few

Ephemeroptera (i.e. Baetis and Tricorythodes) and Trichoptera (i.e. Cheumatopsyche, Hydropsyche and

Hydroptila) that are tolerant to a wide-range of environmental conditions (i.e. mobile sand substrates,

variable flows, extreme temperatures, low dissolved oxygen). High WSII scores for stations in Segment

4 were influenced by favorable scores in the Ephemeroptera, Trichoptera and Total Taxa richness

metrics. As stated in the discussion of Segment 3, these metrics may be inflated due to the larger

number of taxa a large river naturally supports relative to a small stream and quite possibly nutrient

enrichment. Low scores for ‘Percent Trichoptera (less Hydropsychidae - % within community)’ indicated

that stations had largely tolerant Hydropsychid caddisflies. However, ‘Percent of Ephemeroptera (less

Baetidae - % within community)’ scored moderately well at most stations, because Tricorythodes minutes

was the dominant non-Baetid Ephemeroptera taxa. Though commonly found in plains streams,

Tricorythodes minutes can become dominant during and after periods of increased suspended sediment

inputs (Ward 1992), such as the annual Guernsey ‘silt run’ and irrigation return flows. The high relative

abundance of collector-gatherers resulted in low ‘Percent Collector-gatherer’ metric scores at sites below

Guernsey Dam. A high density of collectors generally indicates sparse riparian cover and/or

anthropogenic nutrient inputs, which may result in more fine particulate matter in the system.

The available biological evidence suggests the benthic macroinvertebrate community is limited, likely due

to flow regulation and resultant changes in habitat and physicochemical conditions, sedimentation, and

possible nutrient enrichment. This information supports knowledge by the WGFD (Fisheries Section at

http://gf.state.wy.us) that the stream fisheries are known to be limited below Glendo and Guernsey Dams.

However, because of the discrepancies in model results, limitations of the models in the assessment of

large flow-regulated river segments, and the absence of an appropriate reference condition, it is difficult to

make a conclusive determination of the degree to which the North Platte River in Segment 4 supports

aquatic life uses.

9.0 QUALITY ASSURANCE/QUALITY CONTROL

Station OA/QC reports are attached to this report. All physical, biological and chemical data collected by

the WDEQ/WQD were determined to be complete and accurate.

38

10.0 SUMMARY AND CONCLUSIONS

This report is an initial step by WDEQ/WQD to characterize the chemical, physical and biological

conditions of the North Platte River in Wyoming. Based on data collections at WDEQ/WQD, SERCD and

USGS stations and supplemental information from the USBOR and WGFD, the North Platte River falls

along a broad range of conditions. The following narratives describe noteworthy characteristics of the

river and general designated use-support information where appropriate.

• The dominant characteristic of the North Platte River are its flow-regulated conditions controlled

by seven impoundments; Seminoe Reservoir, Kortes Reservoir, Pathfinder Reservoir, Alcova

Reservoir, Gray Reef Reservoir, Glendo Reservoir and Guernsey Reservoir. The impoundments

are primarily for irrigation water storage, flood control and hydropower generation. In addition,

there are three major irrigation canals: Casper Canal, Interstate Canal and Fort Laramie Canal

along with smaller canals that divert water for irrigation purposes. The impoundments and

diversions greatly influence the ecological structure and function of the North Platte River in

Segments 2-4.

• Water temperature and dissolved oxygen concentrations generally met the Wyoming water

quality criteria of 20◦C and 8 mg/L, respectively for Class 1 and 2AB waters. Water temperatures

throughout much of the North Platte River have exceeded 20◦C during the summer low-flow

periods, particularly when demands on the river are at their peak. For similar reasons, dissolved

oxygen concentrations have fallen below 8 mg/L during summer-low flow periods.

• Total phosphorous and nitrate-nitrogen concentrations downstream of Saratoga, Wyoming have

exceeded the federally recommended nutrient reference conditions for the respective ecoregion.

Though limited sampling below Kortes and Pathfinder Dams did not detect nitrate-nitrogen or total

phosphorous, thick stands of aquatic macrophytes suggest nutrient enrichment. Downstream of

Casper, Wyoming to the Wyoming/Nebraska stateline, nitrate-nitrogen and to a lesser extent total

phosphorous exceeded the federally recommended maximum nutrient concentrations for the

respective ecoregions. A single exceedence of the recommended maximum total phosphorous

concentration was found near the Nebraska stateline. Non-point source runoff and groundwater

contributions from agricultural lands, discharges from municipal wastewater treatment plants,

stormwater runoff, malfunctioning septic systems and possibly nutrient-rich hypolimnetic reservoir

releases are suspected sources. Based on exceedences of federally recommended nutrient

reference conditions and visual observations, many segments of the North Platte River from

Saratoga downstream to the Wyoming/Nebraska stateline may be experiencing nutrient

enrichment. However, the State of Wyoming does not have numeric nutrient criteria as a

benchmark for comparison. In addition, use of biological indicators to detect nutrient enrichment

is problematic due to the synergistic effects of multiple human activities in the watershed and

limitations in determining specific cause(s) of impact. Because of these complexities, the

39

available information are insufficient to conclude whether nutrient enrichment is impacting

the ability of the North Platte River to support de signated uses .

• Concentrations of heavy metals were either non-detect or below the hardness-dependent water

quality criteria. However, selenium concentrations in the river near the Kendrick Project area and

the City of Casper have exceeded the 5 ug/L chronic aquatic life criterion. These data support

the current State of Wyoming 303(d) listing of the North Platte River upstream and

downstream an undetermined distance from the City o f Casper for exceedence of the

selenium criterion .

• In general, single-sample fecal coliform concentrations in the river were below the single-sample

maximum E. coli concentration of 235 col/100 mL for high use swimming areas on waters

designated for primary contact recreation. The exception was a stretch of the river downstream

of the City of Casper wastewater treatment facility where a single sample exceeded this criterion.

The fecal coliform geometric mean concentrations in the river above and below the Torrington

wastewater treatment facility were below the geometric mean E. coli criterion of 126 col/100 mL

for primary contact recreation waters. However, more samples are needed both spatially and

temporally to effectively evaluate support of contact recreation uses. Therefore, available data

are insufficient to determine support of contact recrea tion .

• Bank and channel conditions throughout most of Segments 1, 2 and 3 were considered stable

with sufficient riparian vegetation and coarse material to minimize erosion during high flows.

Sediment contributions from Sage Creek did not appear to have resulted in excessive

sedimentation at recently monitored (post-2002) stations in the lower portion of Segment 1. BMP

efforts to control sediment loading in Sage Creek likely contributed to this condition. Bates Creek

in Segment 2 appears to contribute excess sediment to the river, though it has not resulted in

embedded riffles in the river immediately downstream from the confluence. Evidence of

sedimentation in the form of newly developed mid-channel and point-bars in addition to

embedded riffles were noted near the lower end of Segment 3. This is suspected to be due to a

reduction in natural sediment transport due to upstream reservoir controls and diversions.

Stormwater drains for the cities of Casper and Douglas also may contribute sediment to the river.

Physical conditions between Glendo and Guernsey Reservoirs in Segment 4 were generally

adequate with sufficient vegetation along the banks and riparian zones to maintain stability and

minimize erosion during high flows. Riffles were generally free of fine sediment with little evidence

of excessive sedimentation or erosion. However, less sediment carrying capacity due to

regulated releases from Glendo Dam appear to have resulted in sedimentation of the river

immediately upstream of Guernsey Reservoir. Variable reservoir releases, in addition to irrigation

return flows appear to exert a considerable influence on the banks of the North Platte River below

Guernsey Dam. Bank and channel conditions below Guernsey Dam were considered moderate

to highly unstable with large areas of the bank susceptible to erosion and failure during high

40

flows. Bank scour, channel changes, sediment in irrigation return flows and municipal stormwater

drains and reductions in sediment carrying capacity from irrigation diversions and reservoir

operations have likely contributed resulted in excessive sedimentation in the river below

Guernsey Dam.

• Based on the WSII and WY RIVPACS biotic indices and other supporting information, the North

Platte River upstream of Saratoga, Wyoming was cons idered fully-supportive of cold-water

fisheries, non-game fisheries and aquatic life othe r than fish uses at the time of sampling.

However, because data from this section is >5 years old and it is unknown how recent

drought conditions have affected this reach, a rece nt use-support determination cannot be

made. In general, the river above and below Sage Creek declined in biological condition from

1999 to 2001 predominantly due to low flows associated with drought and improved from 2002 to

2005. Excess sediment loading from Sage Creek possibly contributed to the biological condition

decline in the North Platte River below Sage Creek. It’s likely that improved climatic and flow

conditions since the multi-year drought in the late 1990s and 2000/2001, and sediment reduction

efforts along Sage Creek have contributed to the improved biological condition in 2002-2005.

There was a decline in biological condition below Sage Creek in 2005, though this was believed

to be caused by scouring and conveyance of accumulated sediment in Sage Creek after an

intense precipitation event. The North Platte River above and below Sage Creek is currently

considered ‘indeterminate and partial/non-support’ for the aquatic life use criteria according to the

WSII and WY RIVPACS, respectively. However, the general positive trend suggests biological

condition will continue to improve as BMPs along Sage Creek and its confluence with the North

Platte River are maintained and normal flow conditions continue. It appears that biological

condition of the North Platte River near Seminoe Reservoir was also impacted by drought

conditions in 2002. It is assumed that biological condition in this area will improve with the onset

of normal flow conditions. Prior to making a final aquatic life use-support de termination on

the North Platte River below Saratoga, Wyoming, fur ther monitoring should be conducted

to document whether biological condition, particula rly below Sage Creek, continues to

improve .

• Flow manipulations and associated physicochemical and physical habitat changes (i.e. habitat

alterations, scouring, bank erosion and sedimentation) from reservoir releases and diversions

appear to have the most significant impact to benthic macroinvertebrate communities of the North

Platte River from Seminoe and Kortes Dams downstream to the Wyoming/Nebraska stateline.

Other impacts to the benthic macroinvertebrates communities downstream of the reservoirs

include selenium loading near the Kendrick Project area, sediment loading from irrigation return

flows and reservoir releases (i.e. annual Guernsey ‘silt run’), and possible nutrient enrichment.

Because of the cascading effects of these influences on the ecology and function of a river, and

the absence of an expected biological reference or best attainable condition for large flow-

41

regulated river segments of the North Platte River, the available information are insufficient to

determine use-support for cold-water fisheries, non -game fisheries and aquatic life other

than fish for the North Platte River from Seminoe a nd Kortes Dams downstream to the

Wyoming/Nebraska stateline.

• The available chemical, biological and physical information are insufficient to make

determinations on support of drinking water and fis h consumption uses.

• Available information are insufficient to make dete rminations on support of wildlife,

industrial, agricultural and scenic value uses . WDEQ/WQD generally assumes that

insufficient information exists to make a determination on these uses if insufficient information

also exists to make a determination on the corresponding aquatic life use.

11.0 RECOMMENDATIONS

• Implement efforts to define a reference or best attainable condition for large flow-regulated river

segments of the North Platte River.

• Additional monitoring of the North Platte River from Saratoga, Wyoming downstream to Seminoe

Reservoir, particularly above and below Sage Creek, to track trends in biological condition

associated with drought recovery and BMP sediment reduction efforts on Sage Creek.

• Future bacteria monitoring to effectively determine contact recreation use support.

• Future investigation into whether nutrient enrichment is occurring in the North Platte River and its

effect on designated use support.

• Future sampling and analysis of fish tissue to determine fish consumption use support.

• Additional monitoring throughout the North Platte River to track conditions over time.

• Monitoring of additional sites between Casper and Glendo Reservoir to document conditions.

• Continue sampling for water chemistry within the Kendrick Project area to track selenium trends.

• Additional investigation into sediment loading within and from Bates Creek.

12.0 SIGNATURES

AUTHOR _____________________________________________________________________

PEER REVIEWER ______________________________________________________________

PEER REVIEWER ______________________________________________________________

MONITORING PROGRAM SUPERVISOR ___________________________________________

42

13.0 LITERATURE CITED

Anderson, N.H. and D.M. Lehmkuhl. 1968. Catastrophic drift of insects in a woodland stream. Ecology

49:198-206.

Hargett, E.G., J.R. ZumBerge, C.P. Hawkins, and J.R. Olson. 2007. Development of a RIVPACS-type predictive model for bioassessment of wadeable streams in Wyoming. Ecological Indicators 7:807-826.

Hargett, E.G., J.R. Zumberge and C.P. Hawkins. 2005. Development of a RIVPACS Model for Wadeable

Streams of Wyoming. Wyoming Department of Environmental Quality, Water Quality Division, Cheyenne,

WY.

Hargett, E.G. and J.R. Zumberge. 2006. Redevelopment of the Wyoming Stream Integrity Index (WSII)

for Assessing the Biological Condition of Wadeable Streams in Wyoming. Wyoming Department of

Environmental Quality, Water Quality Division, Cheyenne, WY.

Hawkins, C.P. 2006. Quantifying biological integrity by taxonomic completeness: evaluation of a

potential indicator for use in regional and global-scale assessments. Ecological Applications In press.

King, K. 1993. A bioassessment method for use in Wyoming stream and river water quality monitoring.

Wyoming Department of Environmental Quality. Water Quality Division, Cheyenne, WY.

Nestler, J.M., C.H. Walburg, J.F. Novotny, K.E. Jacobs, and W.D. Swink. 1986. Handbook of Reservoir

Releases or Fisheries and Environmental Quality. Instruction Report E-86-3. U.S. Army Engineer

Waterways Experiment Station, Vicksburg, Miss.

Omernik, J. M. and A. L. Gallant. 1987. Ecoregions of the west-central United States (map). United States

Environmental Protection Agency, Corvallis, OR.

Perry, S.A. and W.B. Perry. 1986. Effects of experimental flow regulation on invertebrate drift and

stranding in the Flathead and Kootenai Rivers, Montana, USA. Hydrobiologia 134:171-182.

Petts, G.E. 1984. Impounded Rivers, Perspectives for Ecological Management. John Wiley and Sons,

New York, NY.

Plafkin, J.L., M.T. Barbour, K.D. Porter, S.K. Gross, and R.M. Hughes. 1989. Rapid bioassessment

protocols for use in streams and rivers. Office of Water (WH-553), EPA/444/4-89-001. Washington, D.C.

43

Poff, N.L., J.D. Allan, M.B. Bain, J.R. Karr, K.L. Prestegaard, B. Richter, R. Sparks and J. Stromberg.

1997. The natural flow regime: a paradigm for river conservation. BioScience 47:769-784.

SERCD 2006. Sage Creek Watershed Project Phase II Final Report Project No. ON208. Saratoga-

Encampment-Rawlins Conservation District. Saratoga, WY.

Stanford, J.A., W. Ward, W.J. Liss, C.A. Frissell, R.N. Williams, J.A. Lichatowich and C.C. Coutant. 1996.

A general protocol for restoration of regulated rivers. Regulated Rivers: Research and Management

13:213-224.

Thorp, J.H. and A.P. Covich. 2001. Ecology and Classification of North American Freshwater

Invertebrates 2nd Edition. Academic Press. 1056 pp.

Trotzky, H.M. and R.W. Gregory. 1974. The effects of water flow manipulation below a hydroelectric

power dam on the bottom fauna of the upper Kennebec River, Maine. Transactions of the American

Fisheries Society 103:318-324.

USEPA 2000a. Ambient Water Quality Criteria Recommendations-Information Supporting the

Development of State and Tribal Nutrient Criteria for Rivers and Streams in Nutrient Ecoregion II. United

States Environmental Protection Agency, Office of Water, EPA 822-B-00-015.

USEPA 2000b. Ambient Water Quality Criteria Recommendations-Information Supporting the

Development of State and Tribal Nutrient Criteria for Rivers and Streams in Nutrient Ecoregion III. United


USEPA 2001a. Ambient Water Quality Criteria Recommendations-Information Supporting the

Development of State and Tribal Nutrient Criteria for Rivers and Streams in Nutrient Ecoregion IV. United


USEPA 2001b. Ambient Water Quality Criteria Recommendations-Information Supporting the

Development of State and Tribal Nutrient Criteria for Rivers and Streams in Nutrient Ecoregion V. United


USGS 1985. Geologic map of Wyoming. Compiled by J.D. Love and A.C. Christansen. Sheets 1,2, and

3. Reston, VA. G85135.

44

Walburg, C.H., J.F. Novotny, K.E. Jacobs, T.M. Campbell, and W.D. Swink. 1980. Water Quality,

Macroinvertebrates, and Fisheries in Tailwaters and Related Streams; An Annotated Bibliography.

Technical Report E-81-8, prepared by the U.S. Department of Interior for the U.S. Army Engineer

Waterways Experiment Station, Vicksburg, Miss.

Walburg, C.H., J.F. Novotny, K.E. Jacobs, W.D. Swink, T.M. Campbell, J. Nestler and G.E. Saul. 1981.

Effects of Reservoir Releases on Tailwater Ecology: A Literature Review. Technical Report E-81-12,

prepared by the U.S. Department of Interior for the U.S. Army Engineer Waterways Experiment Station,

Vicksburg, Miss.

Ward, J.V. 1992. Aquatic Insect Ecology: 1. Biology and Habitat. John Wiley & Sons, Inc. New York, NY.

438 pp.

Ward, J.V. and J.A. Standford. 1995. Ecological connectivity in alluvial river systems and its disruption by

flow regulation. Regulated Rivers 11:105-119.

WDEQ/WQD. 1998. Beneficial use reconnaissance project-wadeable stream monitoring methodology.

Wyoming Department of Environmental Quality, Water Quality Division, Cheyenne, WY.

WDEQ/WQD. 2001a. Quality Assurance Project Plan (QAPP) for Beneficial Use Reconnaissance Project

(BURP) Water Quality Monitoring. Wyoming Department of Environmental Quality, Water Quality Division,

Watershed Program, Cheyenne, WY.

WDEQ/WQD. 2001b. Wyoming’s method for determining water quality condition of surface waters.

Wyoming Department of Environmental Quality, Water Quality Division, Cheyenne, WY.

WDEQ/WQD. 2004. Manual of Standard Operating Procedures for Sample Collection and Analysis.

Wyoming Department of Environmental Quality, Water Quality Division, Watershed Program, Cheyenne,

WY.

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45

APPENDIX

46

Appendix 1 – Summary of constituent concentrations at the four USGS fixed stations on the North Platte River. Boxes represent the 25-75%ile range, whiskers represent the non-outlier range, squares are median values and circles are outliers.

47

Appendix 1 (cont.) – Summary of constituent concentrations at the four USGS fixed stations on the North Platte River. Boxes represent the 25-75%ile range, whiskers represent the non-outlier range, squares are median values and circles are outliers.

48


49


50

Appendix 2-1 – Physicochemical results at WDEQ/WQD stations on the North Platte River upstream of Seminoe Reservoir.

SR12 SR24 WB5 WB29 WB220 WBI21 WB174Date 10/14/97 8/29/96 10/14/97 10/20/97 7/29/04 10/20/97 9/18/02Time 15:45 11:25 11:25 NM 10:40 NM 8:01Temperature C 7.1 16.8 4.2 NM 19.5 NM 11.2pH 8.2 8.3 8.6 NM 8.7 NM 8.5Conductivity (uS/cm) 148 204 171 NM 413 NM 580Dissolved Oxygen (mg/L) 10 8.5 11.2 NM 7.3 NM 7.9Turbidity (NTU) 3.5 1.4 3.0 NM 8.0 NM 6.6TSS (mg/L) 5 2 4 NM 10 NM 7Alkalinity (mg/L as CaCO3) 90 90 80 NM 140 NM 130Sulfate (mg/L) 14 11 16 NM 58 NM 151Chloride (mg/L) <5 <5 <5 NM 5 NM 26Nitrate (mg/L as N) <0.1 <0.1 <0.1 NM <0.1 NM <0.1Total Phosphorus (mg/L) <0.1 <0.1 <0.1 NM <0.1 NM <0.1Total Hardness (mg/L as CaCO3) 72 93 90 NM 156 NM 192Lead (ug/L) NM NM NM NM NM NM <5Total Copper (ug/L) NM NM NM NM NM NM <10Mercury (ug/L) NM NM NM NM NM NM <1Sheen None None None None None None NoneColor None None None None Pale Yellow None NoneOdor None None None None None None NoneDischarge (cfs) 300 500 225 250 430 20 58

NM = Not Measured

51

Appendix 2-2 – Physicochemical results at station SERCD-W1 on the North Platte River upstream of Seminoe Reservoir.

Date TimeDischarge

(cfs)Temperature

C

Dissolved Oxygen (mg/L)

Conductivity (uS/cm) pH

TDS (mg/L)

Turbidity (NTU)

TSS (mg/L)

Total Phosphorus

(mg/L)

5/27/1998 15:03 2990 11.6 10.0 128 8.3 81 NM 22.4 0.186/22/1998 15:31 4080 13.5 8.8 186 8.1 118 NM 12.3 0.107/16/1998 16:05 1330 20.6 9.6 263 8.9 168 61.2 4.3 <0.058/5/1998 15:30 1150 18.6 9.6 273 NM 175 14.1 8.0 0.11

10/26/1998 10:00 NM 6.1 10.2 278 8.4 178 5.3 3.7 0.0612/2/1998 12:00 NM 3.2 15.0 247 9.0 161 5.9 4.1 0.064/20/1999 14:39 1010 9.0 9.3 292 8.8 187 15.9 14.0 0.115/24/1999 17:05 5010 9.1 9.9 1164 7.7 NM 22.1 56.0 0.126/8/1999 11:05 4740 9.4 9.4 123 7.6 79 11.6 16.0 0.086/23/1999 14:45 6320 13.2 8.3 148 7.7 95 9.1 15.0 0.067/27/1999 12:25 810 21.2 8.5 229 8.7 146 3.5 9.0 0.048/31/1999 15:20 482 18.9 8.2 1297 8.5 830 4.9 3.2 0.1210/27/1999 16:36 NM 7.1 9.2 297 8.8 190 5.5 9.0 0.084/12/2000 12:45 1278 7.9 9.3 252 8.1 161 31.5 50.0 0.165/8/2000 13:15 3169 6.9 7.8 98 7.9 63 20.8 30.0 0.146/8/2000 13:35 2474 16.3 7.3 166 7.9 106 7.3 10.0 0.116/27/2000 14:40 722 17.8 7.1 343 8.3 220 2.2 2.9 0.037/31/2000 14:05 222 22.6 8.4 337 8.2 216 11.5 7.3 0.024/18/2001 1540 NM 13.0 7.3 204 8.6 131 3.7 18.0 0.055/1/2001 1053 NM 9.1 7.5 112 8.0 71 38.3 62.0 0.115/17/2001 1545 NM 9.5 6.3 80 7.7 53 30.1 32.0 0.126/12/2001 1145 NM 15.2 6.6 180 7.9 116 9.1 28.0 0.11

Maximum 6320 22.6 15.0 1297 9.0 830 61.2 62.0 0.18Minimum 222 3.2 6.3 80 7.6 53 2.2 2.9 0.02Median 1330 12.3 8.6 238 8.2 146 10.3 13.2 0.11Mean 2386 12.7 8.8 304 8.2 169 15.7 19.0 0.09

Station SERCD-W1

NM = No measurement

52


Date TimeDischarge

(cfs)Temperature

C



TDS (mg/L)

Turbidity (NTU)

TSS (mg/L)

Total Phosphorus

(mg/L)

5/27/1998 13:12 NM 11.7 9.4 153 8.2 97 15.9 18.8 0.056/22/1998 14:15 NM 14.1 8.6 240 8.0 154 5.4 17.0 0.097/15/1998 13:41 NM 20.5 10.3 306 8.9 196 33.6 7.3 0.098/5/1998 13:25 NM 18.4 8.3 371 9.5 237 NM 12.2 0.08

10/26/1998 11:00 NM 6.5 9.5 392 8.4 251 6.3 6.2 0.0412/2/1998 10:50 NM 2.0 14.9 349 8.2 224 3.7 2.8 0.034/20/1999 13:38 NM 8.9 9.4 360 8.0 230 5.9 17.0 0.065/24/1999 16:10 NM 9.5 9.9 NM 7.7 NM 33.7 76.0 0.126/8/1999 9:50 NM 10.4 8.6 155 7.7 99 12.4 18.0 0.076/23/1999 13:30 NM 12.9 8.0 176 7.6 113 19.6 175.0 0.207/27/1999 11:25 NM 20.8 8.5 268 8.8 172 2.1 6.0 0.038/31/1999 13:50 NM 18.3 8.1 322 8.7 206 1.1 5.2 0.1710/27/1999 15:20 NM 7.6 16.2 396 8.8 254 4.9 2.3 0.044/12/2000 11:12 NM 7.9 8.8 282 8.1 181 37.9 58.0 0.125/8/2000 10:43 NM 7.2 9.2 114 7.9 72 23.3 32.0 0.106/8/2000 11:35 NM 16.3 7.5 193 7.8 124 7.6 6.8 0.106/27/2000 13:30 NM 18.8 6.8 371 8.4 237 2.4 39.0 0.157/31/2000 12:00 NM 21.7 5.5 380 8.2 243 NM 10.0 0.054/18/2001 1440 NM 12.8 9.2 257 8.6 165 7.0 24.0 0.125/1/2001 955 NM 9.6 8.0 137 8.1 88 33.6 59.5 0.145/17/2001 1455 NM 9.7 8.0 85 7.3 55 32.3 25.3 0.126/18/2001 1000 NM 15.3 5.6 2 7.6 137 2.8 3.0 0.04

Maximum 21.7 16.2 396 9.5 254 37.9 175.0 0.20Minimum 2.0 5.5 2 7.3 55 1.1 2.3 0.03Median 12.2 8.6 268 8.2 172 7.3 17.0 0.09Mean 12.8 9.0 253 8.2 168 14.6 28.2 0.09

Station SERCD-W2

NM = No measurement

53


Date TimeDischarge

(cfs)Temperature

C



TDS (mg/L)

Turbidity (NTU)

TSS (mg/L)

Total Phosphorus

(mg/L)

5/27/1998 11:50 NM 12.3 9.4 204 8.2 131 12.0 10.2 0.056/22/1998 12:51 NM 15.5 8.2 307 8.0 196 21.4 25.0 <0.057/15/1998 12:25 NM 21.1 9.6 322 8.8 206 NM 8.0 <0.058/5/1998 11:15 NM 18.3 8.3 405 9.5 258 54.2 10.4 0.11

10/26/1998 11:50 NM 7.3 9.3 441 8.6 282 11.9 11.5 0.0912/2/1998 9:15 NM 2.0 10.5 395 8.6 253 10.6 60.0 0.104/20/1999 10:23 NM 8.2 9.1 469 8.0 300 15.2 325.0 0.195/24/1999 14:40 NM 13.2 9.5 NM 7.6 NM 66.3 101.0 0.126/8/1999 8:10 NM 11.1 8.0 224 7.8 144 28.3 36.0 0.106/23/1999 11:45 NM 14.4 7.1 211 7.7 134 15.8 202.0 0.287/27/1999 9:15 NM 20.1 6.9 293 8.8 188 4.1 3.6 0.098/31/1999 12:30 NM 19.2 7.7 363 8.5 232 13.3 58.0 0.1010/27/1999 14:00 NM 7.4 9.4 454 8.8 291 6.7 5.4 0.104/12/2000 9:00 NM 7.5 8.7 305 7.4 195 38.0 77.0 0.175/8/2000 9:00 NM 8.3 8.2 120 8.2 76 31.5 51.0 0.116/8/2000 9:20 NM 16.1 7.6 206 8.0 132 10.7 19.0 0.116/27/2000 12:15 NM 19.1 9.2 384 8.6 246 2.1 4.5 <0.027/31/2000 10:55 NM 20.3 5.9 387 8.0 247 6.2 15.0 0.02

Maximum 21.1 10.5 469 9.5 300 66.3 325.0 0.28Minimum 2.0 5.9 120 7.4 76 2.1 3.6 0.02Median 13.8 8.5 322 8.2 206 13.3 22.0 0.10Mean 13.4 8.5 323 8.3 207 20.5 56.8 0.12

NM = No measurement

Station SERCD-W3

54


Date TimeDischarge

(cfs)Temperature

C



TDS (mg/L)

TSS (mg/L)

1/15/1998 12:25 491 0.0 11.4 423 8.2 247 4.03/16/1998 11:45 819 1.0 NM 431 8.1 296 14.04/6/1998 10:15 1200 6.0 8.8 438 8.2 363 28.04/24/1998 12:00 1170 12.5 8.7 417 8.3 275 24.05/7/1998 11:15 2820 8.0 8.9 207 7.9 155 74.05/26/1998 9:20 2870 10.0 8.4 189 8.0 119 23.06/10/1998 10:30 2820 10.5 9.8 276 8.0 178 NM6/25/1998 11:00 3560 14.0 8.7 242 8.1 176 19.07/20/1998 11:00 1020 21.5 8.2 289 9.1 181 12.08/31/1998 13:50 453 18.5 9.7 369 8.7 237 11.09/10/1998 15:20 342 20.0 8.2 390 8.6 250 2.010/23/1998 11:20 560 8.0 9.8 456 8.2 310 13.011/17/1998 10:00 833 2.0 9.3 433 8.2 300 20.012/15/1998 10:15 480 0.0 11.1 487 7.8 365 3.01/29/1999 10:00 405 1.0 10.9 435 7.9 314 4.02/25/1999 12:55 490 0.0 11.3 394 8.4 281 6.03/24/1999 12:00 984 7.0 10.3 353 8.1 250 31.04/21/1999 11:15 1170 8.5 10.4 361 8.1 252 33.05/26/1999 10:50 6060 10.5 8.9 160 7.7 119 101.06/22/1999 12:10 6520 14.1 8.2 207 7.9 127 24.06/29/1999 9:50 3890 14.5 8.1 206 8.0 130 17.07/27/1999 11:10 928 21.1 8.1 291 8.8 179 4.08/17/1999 10:10 488 17.2 9.8 374 8.4 247 14.09/8/1999 10:30 479 12.5 8.8 378 8.5 242 8.0

Maximum 6520 21.5 11.4 487 9.1 365 101.0Minimum 342 0.0 8.1 160 7.7 119 2.0Median 956 10.3 8.9 372 8.2 247 14.0Mean 1702 9.9 9.4 342 8.2 233 21.3

NM = No measurement

Station SERCD-W4

55

Appendix 2-6 – Qualitative habitat assessment, biological indicators and substrate composition for WDEQ/WQD stations on the North Platte River upstream of Seminoe Reservoir.

STATION ID SR12 SR24 WB5 WB29 WB220 WBI21 WB174

EcoregionSouthern Rockies

Stream Type (Reference=R, Non-Reference=NR) R R R R R NR N R

Habitat Parameters (Max. Score)Epifaunal Substrate/Available Cover (20) 16Bottom Substrate-Percent Fines (20) 16 13 18 19 17 17Instream Cover for Fish (20) 16 16 16 17 18 15Embeddedness (20) 14 14 11 11 7 2 18Velocity/Depth (20) 15 14 17 16 19 16 16Channel Flow Status (20) 18 10Sediment Deposition (20) 15Channel Shape (15) 7 7 7 11 11 11Pool/Riffle Ratio (15) 13 7 14 7 15 10Frequency of Riffles (20) 11Channelization/Alteration ( b15 or a,c20) 14 12 14 14 15 14 19Width to Depth (15) 1 2 3 7 1 7Bank Vegetation Protection (10) 9 9 9 6 9 9 5.5Bank Stability (10) 9 9 9 6 9 8 5.5Disruptive Pressures (Riparian Zone) (10) 8 5 9 9 10 9Riparian Vegetative Zone Width (10) 9 7 8 9 10 9 6HABITAT ASSESSMENT TOTAL >10% Riffle/Run ( a170, b180 or c200 possible) b131 b115 b135 b132 c159 b127 a122

HABITAT ASSESSMENT (Percent of Maximum Score) 72.8 63 .9 75.0 73.3 79.5 70.6 71.8PERCENT COMPARABILITY TO MEAN REFERENCE HABITAT CON DITION (Southern Rockies = 72.8, Wyoming Basin = d72.9) 100 87.7 102.9 100.5 109.1 96.8 98.5

Biological Indicators*Periphyton 3 3 3 2 2 2 2Filamentous Algae 2 0 2 2 2 2 2Rooted Macrophytes 2 1 2 2 2 2 2Floating Macrophytes 2 0 2 2 0 2 0Fish 1 2 0 2 2 2 2Slimes 0 0 0 0 0 0 0

Substrate CompositionCobble 60.0 70.0 64.0 76.0 67.5 36.0 48.1Coarse Gravel 25.0 6.0 20.0 15.0 17.9 34.0 22.1Fine Gravel 10.0 9.0 12.0 6.0 8.1 23.0 19.4Sand 5.0 15.0 4.0 3.0 5.4 7.0 10.4Silt 1.1Clay-Hard Pack (solid, slick)Organic (f ine, black, odor)Precipitate

Weighted Embeddedness 73.5 75.2 47.6 55.0 46.0 25.2 96.6

Mean Water Velocity (ft/sec) 2.5 1.5 1.98 2.1 2.05 1.9 1.09

* 4-Dominant, 3-Abundant, 2-Common, 1-Rare, 0-Absent

Wyoming Basin

a Large river habitat assessment, b Stream habitat assessment pre-1998, c Stream habitat assessment post-1998d Mean of habitat assessment (percent of maximum scores) for stations SR24, WB5, WB29, and WB220

56

Appendix 2-7 – Summary of macroinvertebrate collection results at WDEQ/WQD stations on the North Platte River above Seminoe Reservoir.

Taxon A bundance % C omposit ion A bundance % C omposit ion A bundan ce % C omposit ion A bundance % C omposi t ion A bundance % C om posi t ion A bundance % C omposi t ion A bundance % C omposit io n

Hirudinea Hirudinea 9 0.17 27 0.19 13 0.18

Nematoda Nematoda 8 0.16 27 0.19 23 0.19

Enchytraeidae 36 0.7Imm. Tubificid w/ cap setae 9 0.17 23 0.19Imm. Tubificid w/o cap setae 54 1.04Nais 135 0.93Nais elinguis 16 0.32Ophidonais serpentina 5 0.19

Ferrissia 22 3.35 452 9.05 131 4.85 422 8.17 161 1.1 13 0.18 46 0.37Helisoma 8 0.19 18 0.35Physidae 108 0.74Stagnicola 23 0.19

Bivalvia Sphaeriidae 9 0.17 27 0.19 46 0.37

Amphipoda Hyallela 27 0.19

Hydrachnida Acari 56 1.13 27 0.19 46 0.37

TOTAL - NON-INSECTS 22 3.35 533 10.66 141 5.22 556 10.78 539 3.7 27 0.36 207 1.68Petrophila 27 0.52 54 0.37 392 3.19TOTAL - LEPIDOPTERA 27 0.52 54 0.37 392 3.19Gomphidae 23 0.19TOTAL - ODONATA 23 0.19Acentrella 269 1.85Acentrella turbida 9 1.47 153 3.07 25 0.93 18 0.35 27 0.36Acerpenna 323 2.22Ameletus 8 0.16Baetis tricaudatus 46 7.13 420 8.4 323 11.94 350 6.78 161 1.1 108 1.43 231 1.88Choroterpes 108 0.74Diphetor hageni 8 0.16Drunella doddsi 13 0.18Drunella grandis/spinifera 30 1.12Ephemera 13 0.18Ephemerella inermis/infrequens 50 7.76 137 2.75 544 20.15 233 4.52 404 5.38Heptagenia/Nixe 32 0.65 5 0.19 9 0.17Paraleptophlebia 1 0.21 50 1.87 404 7.83 296 3.94Rhithrogena 30 4.61 16 0.32 15 0.56 90 1.74 121 1.61Stenonema 138 1.12Tricorythodes minutus 4 0.63 178 3.55 25 0.93 493 9.57 3981 27.3 356 4.48 2283 18.58TOTAL - EPHEMEROPTERA 140 21.8 952 19.06 1018 37.69 1597 30.96 4842 33.2 1318 17.56 2652 21.58Capniidae 3 0.42 10 0.37 9 0.17 13 0.18Chloroperlidae 20 3.14 50 1.87 9 0.17Claassenia sabulosa 15 2.31 16 0.32 15 0.56 36 0.7 27 0.19 27 0.36Isogenoides 3 0.42 8 0.16 15 0.56Isoperla 4 0.63 8 0.16 146 5.41 762 14.78 888 11.83Perlodidae-early instar 4 0.63 8 0.16 20 0.75 27 0.52 40 0.54 346 2.82Pteronarcella 3 0.42 8 0.16Pteronarcys 8 0.16Pteronarcys californica 5 0.19Skwala 8 0.16Taeniopterygidae 9 0.17TOTAL - PLECOPTERA 51 7.97 65 1.29 262 9.7 852 16.52 27 0.19 968 12.9 346 2.82Arctopsyche grandis 16 0.32 5 0.19Brachycentrus occidentalis 11 1.68 81 1.62 126 4.66 18 0.35 592 4.06 121 1.61Ceraclea 1 0.21 8 0.16Cheumatopsyche 13 2.1 65 1.29 101 3.73 789 15.3 323 2.22 740 9.86 2813 22.89Glossosoma 71 11.11 178 3.55 126 4.66Helicopsyche borealis 32 5.03 16 0.32 25 0.93 90 1.74 27 0.36 46 0.37Hydropsyche 118 18.45 1235 24.72 202 7.46 700 13.57 2744 18.82 3080 41.04 3505 28.52Hydroptila 40 1.49 36 0.7 350 2.4Lepidostoma-sand case larvae 3 0.42 5 0.19Leucotrichia 4 0.63 121 2.42MayatrichiaNectopsyche 81 0.56Neotrichia 18 0.35 54 0.37Ochrotrichia 9 0.17Oecetis 7 1.05 89 1.78 10 0.37 9 0.17 161 1.1 40 0.54 92 0.75Protoptila 38 5.87 557 11.15 25 0.93 254 2.07Psychomyia 77 11.95 299 5.98 81 2.99 27 0.52 27 0.19 565 7.53Rhyacophila Coloradensis Gr. 24 0.48TOTAL - TRICHOPTERA 375 58.49 2687 53.8 746 27.61 1695 32.87 4332 29.71 4573 60.93 6710 54.6Cleptelmis 18 0.35Dubiraphia 67 0.9Dytiscidae 1 0.21Microcylloepus 9 0.17 161 1.1 67 0.9 1222 9.94Ochthebius 23 0.19Optioservus 22 3.35 105 2.1 116 4.29 144 2.78 161 1.1 94 1.25 23 0.19Zaitzevia 3 0.42 65 1.29 45 1.68 117 2.26 242 3.23 277 2.25TOTAL - COLEOPTERA 26 3.98 169 3.39 161 5.97 287 5.57 322 2.21 471 6.27 1545 12.57Atherix 4 0.63 32 0.65Ceratopogoninae 9 0.17 27 0.19Dicranota 13 0.18Hemerodromia 8 0.16 9 0.17 23 0.19Hexatoma 8 0.16 27 0.19 108 1.43 23 0.19Pericoma 13 0.18Simulium 1 0.21 32 0.65 54 0.37 46 0.37TOTAL - DIPTERA 5 0.84 81 1.62 18 0.35 108 0.74 135 1.79 92 0.75Cardiocladius 1 0.21 32 0.65Chironomidae-pupae 3 0.42 137 2.75 35 1.31 9 0.17 350 2.4Conchapelopia 13 0.18Cricotopus Nostococladius 65 1.29 27 0.19Cricotopus trifascia 27 0.19Eukiefferiella 5 0.84 32 0.65 5 0.19Lopescladius 1 0.21 5 0.19 115 0.94Micropsectra 5 0.19Microtendipes 1 0.21 24 0.48 35 1.31 9 0.17Orthocladius 3 0.42 91 3.36 36 0.7Orthocladius complex 8 1.26 32 0.65 181 6.72 9 0.17Pagastia 27 0.19Polypedilum 18 0.35 915 6.27 115 0.94Potthastia Longimana Gr. 9 0.17Rheotanytarsus 8 0.16 10 0.37 2448 16.79Stempellinella 24 0.48Tanypodinae 188 1.29Thienemannimyia Gr. 8 0.16 5 0.19 9 0.17 296 2.03 69 0.56Tvetenia 145 2.91 27 0.52 23 0.19Tvetenia bavarica grp. 81 0.56TOTAL - CHIRONOMIDAE 23 3.56 508 10.18 373 13.81 126 2.43 4359 29.9 13 0.18 322 2.62GRAND TOTAL 642 100 4995 100 2701 100 5158 100 14583 100 7505 100 12289 100

WB174 (2002)

Olig

ocha

eta

SR12 (1997) SR24 (1996) WB5 (1997) WBI21 (1997)WB220 (2004)WB29 (1997)

Insecta

Gastropoda

57

Appendix 2-8 – Summary of macroinvertebrate collection results at station SERCD1 on the North Platte River above Seminoe Reservoir.

Taxon Ab und ance % Co mpo si t io n Ab und ance % Co mp osit io n A bundan ce % C o mp osit io n Ab und ance % C o mp osit io n Ab und ance % Co m po si t io n Ab und ance % Co mpo si t io n

Hirudinea Hirudinea 12 0.15 40 1.39 40 0.33 37 1.24 121 1

Nematoda Nematoda 5 0.18

Nais bretscheri 8 0.17Nais communis 12 0.15Ophidonais serpentina 15 0.34Oligochaeta 222 7.64 20 0.17 32 1.06 182 1.5

Ferrissia 131 2.87 242 3.06 20 0.69 182 1.5 27 0.89 161 1.33Gyralus 10 0.35 16 0.53Lymnaeidae 10 0.35Pisidium 60 2.08 40 0.33 61 0.5Physella 12 0.15 91 3.13 182 1.5 16 0.53

Bivalvia Sphaerium 62 1.35 323 4.08 20 0.69 242 2 868 7.14

Crangonyx 5 0.17Gammarus 5 0.17 5 0.18 20 0.17Hyallela 8 0.17 660 22.74 545 4.49 59 1.95

Decapoda Orconectes 20 0.17 20 0.17

Hydrachnida Acari 12 0.15 20 0.17 20 0.17

TOTAL - NON-INSECTS 223 4.89 611 7.73 1144 39.41 1292 10.65 199 6.56 1453 11.96Petrophila 15 0.34 161 2.04 30 1.04 182 1.5 5 0.18 81 0.66TOTAL - LEPIDOPTERA 15 0.34 161 2.04 30 1.04 182 1.5 5 0.18 81 0.66Omphiogomphus 12 0.15TOTAL - ODONATA 12 0.15Acentrella insignificans 81 1.02 141 1.16 16 0.53 81 0.66Acerpenna pygmaea 383 3.16Baetidae 46 0.58 5 0.18Baetis tricaudatus 331 7.25 208 2.62 5 0.17 1049 8.65 27 0.89 81 0.66Ephemera 5 0.18Ephemerella inermis/infrequens 477 10.46 23 0.29Ephemerella excrusians 20 0.17Heptagenia/Nixe 23 0.51Fallceon quilleri 20 0.17Paraleptophlebia 85 1.85 23 0.29 5 0.17Rhithrogena 92 2.02Stenonema 11 0.35Tricorythodes minutus 538 11.8 438 5.54 212 7.29 2341 19.3 161 5.32 1957 16.11TOTAL - EPHEMEROPTERA 1546 33.9 819 10.35 222 7.64 3915 32.28 226 7.45 2159 17.77Isoperla 515 11.3 81 1.02 15 0.52 81 0.67 11 0.35 81 0.66Isogenoides 12 0.15Capniidae 15 0.34Chloroperlidae 8 0.17Claassenia sabulosa 8 0.17 35 0.44Perlodidae-early instar 20 0.17TOTAL - PLECOPTERA 546 11.97 127 1.6 15 0.52 81 0.67 11 0.35 101 0.83Brachycentrus occidentalis 8 0.17 12 0.15 101 0.83 16 0.53 363 2.99Ceraclea 40 0.33Cheumatopsyche 754 16.53 2490 31.49 71 2.43 343 2.83 204 6.74 1453 11.96Culoptila 61 0.5Helicopsyche borealis 123 2.7 46 0.58 222 7.64 141 1.16 5 0.18 40 0.33Hesperophylax 5 0.17Hydropsyche 400 8.77 1926 24.34 186 6.42 3935 32.45 382 12.59 3854 31.73Hydroptila 177 3.88 5 0.17 5 0.18Nectopsyche 15 0.34 46 0.58 40 0.33 11 0.35 161 1.33Neotrichia 23 0.51 20 0.17Oecetis 108 2.36 242 3.06 5 0.17 303 2.5 11 0.35 202 1.66Pycnopsyche 30 1.04TOTAL - TRICHOPTERA 1607 35.24 4762 60.2 524 18.06 4884 40.27 635 20.92 6175 50.83Cleptelmis addenda 12 0.15Dubiraphia 38 0.84 23 0.29 101 0.83 22 0.71 40 0.33Dytiscidae 31 0.67 10 0.35Helichus 5 0.17Helophorus 252 8.68Microcylloepus 161 3.54 588 7.43 151 5.21 565 4.66 70 2.3 1211 9.97Optioservus 62 1.35 138 1.75 91 3.13 222 1.83 54 1.77 121 1Zaitzevia 115 2.53 173 2.19 5 0.17 262 2.16TOTAL - COLEOPTERA 408 8.94 934 11.81 595 20.49 888 7.32 145 4.79 1635 13.46Ceratopogoninae 11 0.35Dolichopodidae 10 0.35Hemerodromia 11 0.35Hexatoma 15 0.34 12 0.15Psychoda 10 0.35Simulium 23 0.51 127 1.6 5 0.17 242 2 151 4.96 121 1Tipula 45 1.56TOTAL - DIPTERA 38 0.84 138 1.75 71 2.43 242 2 172 5.67 121 1Chironomidae-pupae 15 0.34 12 0.15 10 0.35 40 0.33Cricotopus 23 0.29 81 0.67 11 0.35Cricotopus bicinctus Gr. 10 0.35 20 0.17 11 0.35Cricotopus trifascia 81 1.02 40 1.39 20 0.17 20 0.17Eukiefferiella 23 0.29 11 0.35 40 0.33Lopescladius 31 0.67Micropsectra 5 0.17Microtendipes 15 0.34 23 0.29 11 0.35 101 0.83Nilotanypus 8 0.17Orthocladius complex 77 1.69 58 0.73 10 0.35 141 1.16 167 5.5Pagastia 12 0.15Parakiefferiella 11 0.35Parametriocnemus 32 1.06Pentaneura 5 0.17 43 1.42Phaenopsectra 10 0.35 11 0.35 20 0.17Polypedilum 8 0.17 35 0.44 61 0.5 22 0.71 202 1.66Procladius 5 0.17Pseudosmittia 25 0.87Rheotanytarsus 15 0.34 171 5.9 121 1 1280 42.2 20 0.17Stempellinella 23 0.29Thienemanniella 58 0.73Thienemannimyia Gr. 8 0.17 10 0.35 141 1.16 22 0.71 20 0.17Tvetenia bavarica grp. 11 0.35Tvetenia vitracies grp. 20 0.17TOTAL - CHIRONOMIDAE 177 3.88 346 4.37 302 10.42 646 5.32 1641 54.08 424 3.49GRAND TOTAL 4560 100 7910 100 2903 100 12128 100 3034 100 12148 100

Gastropoda

Insecta

Amphipoda

SERCD1 (2005)SERCD1 (2002) SERCD1 (2003) SERCD1 (2004)

Oligochaeta

SERCD1 (1999) SERCD1 (2000)

58

Appendix 2-9 – Summary of macroinvertebrate collection results at station SERCD2 on the North Platte River above Seminoe Reservoir.

Taxon A b und ance % C o mp o sit io n A b und ance % C o mp o sit ion A b und an ce % C omp osit io n A b und ance % C o mp o sit io n A b und ance % C o mp o sit io n A b und ance % C o mp o sit io n

Hirudinea Hirudinea 10 0.36

Turbellaria Turbellaria 11 0.18Nematoda Nematoda 5 0.18 3 0.18

Ophiodonais serpentina 6 0.17Oligochaeta 32 0.99 32 1.11 75 5.01 11 0.18

Ferrissia 37 0.85 78 1.99 22 0.66 22 0.74 38 2.5Gyralus 3 0.18Lymnaeidae 5 0.16 5 0.36Pisidium 5 0.16 5 0.18 3 0.18Physella 5 0.16 19 1.25

Decapoda Pacifasticus 6 0.17

Bivalvia Sphaerium 16 0.49 108 1.8

Amphipoda Hyallela 6 0.17 91 2.8 108 3.7 35 2.33 11 0.18Hydrachnida Acari 22 0.51 19 0.5 11 0.33 5 0.18 3 0.18

TOTAL - NON-INSECTS 59 1.36 116 2.98 188 5.76 188 6.47 183 12.16 140 2.34Petrophila 15 0.34 45 1.16 91 2.8 22 0.74 8 0.54 32 0.54TOTAL - LEPIDOPTERA 15 0.34 45 1.16 91 2.8 22 0.74 8 0.54 32 0.54Ophiogomphus 22 0.36TOTAL - ODONATA 22 0.36Acentrella insignificans 32 0.83 5 0.18 13 0.89 151 2.52Ameletus 3 0.18Baetidae 26 0.66Baetis tricaudatus 147 3.39 52 1.32 48 1.66 35 2.33 118 1.98Callibaetis 5 0.16Caenis 5 0.16 5 0.18Ephemera 13 0.33 5 0.16 16 0.55 13 0.89Ephemerella excrusians 279 6.44 54 0.9Leptophlebia 43 1.48 5 0.36McCaffertium 11 0.18Paraleptophlebia 51 1.19 58 1.49 5 0.16 5 0.36Rhithrogena 206 4.75 32 0.83 3 0.18 43 0.72Stenonema 5 0.16 97 3.33 22 1.43Tricorythodes minutus 301 6.95 110 2.81 1307 39.97 834 28.65 196 13.06 904 15.11TOTAL - EPHEMEROPTERA 984 22.71 323 8.28 1334 40.79 1049 36.04 296 19.68 1280 21.4Claassenia sabulosa 22 0.51 19 0.5 5 0.18Capniidae 22 0.51Isoperla 477 11.02 32 0.83 22 0.66 11 0.37 13 0.89 463 7.73Perlodidae-early instar 7 0.17Skwala 7 0.17Taeniopterygidae 3 0.18TOTAL - PLECOPTERA 536 12.37 52 1.32 22 0.66 16 0.55 16 1.07 463 7.73Brachycentrus occidentalis 228 5.25 39 0.99 11 0.33 5 0.18 30 1.97 226 3.78Cheumatopsyche 404 9.32 1111 28.48 167 5.1 221 7.58 38 2.5 398 6.65Culoptila 37 0.85 13 0.33 3 0.18 22 0.36Helicopsyche borealis 22 0.51 78 1.99 22 0.66 11 0.72Hesperophylax 5 0.16 3 0.18Hydropsyche 1240 28.64 1066 27.32 215 6.58 463 15.9 121 8.05 2367 39.57Hydroptila 66 1.53 11 0.33 3 0.18Nectopsyche 13 0.33 5 0.18 8 0.54 32 0.54Neotrichia 6 0.17Oecetis 228 5.25 420 10.76 48 1.48 113 3.88 56 3.76 54 0.9Polycentropus 5 0.16 5 0.18Psychomyia 44 1.02 26 0.66 5 0.16Pycnopsyche 19 1.25TOTAL - TRICHOPTERA 2268 52.37 2771 71.03 490 14.97 812 27.91 291 19.32 3099 51.8Dubiraphia 39 0.99 65 1.97 32 1.11 35 2.33 11 0.18Cleptelmis addenda 6 0.17Helophorus 231 7.07 5 0.18Microcylloepus 191 4.41 181 4.64 511 15.63 447 15.34 59 3.94 377 6.29Optioservus 66 1.53 78 1.99 48 1.66 11 0.72 22 0.36Zaitzevia 66 1.53 129 3.31 27 0.82 43 1.48TOTAL - COLEOPTERA 323 7.46 433 11.09 834 25.49 576 19.78 105 6.98 409 6.83Ceratopogoninae 16 0.55 13 0.89Dolichopodidae 5 0.36Hexatoma 29 0.68 97 2.48 32 0.99 11 0.37 8 0.54 22 0.36Pericoma 54 1.64 8 0.54Simulium 5 0.16 16 0.55 40 2.68 43 0.72Tipula 5 0.16 3 0.18TOTAL - DIPTERA 29 0.68 97 2.48 97 2.96 43 1.48 78 5.19 65 1.08Chironomidae-pupae 6 0.17 16 0.49 11 0.37Chironomus 5 0.18 3 0.18Cladotanytarsus 6 0.17 11 0.37 3 0.18Cricotopus trifascia 6 0.17 5 0.18 11 0.18Cryptochironomus 5 0.16 5 0.18 8 0.54Demicryptochironomus 5 0.18Diamesa 37 0.85Lopescladius 108 1.8Microtendipes 5 0.16 5 0.18 3 0.18 11 0.18Orthocladius complex 29 0.68 102 3.13 16 0.55 299 19.86Orthocladius (Euorthocladius) 7 0.17Parakiefferiella 186 12.34Parametriocnemus 11 0.37Pentaneura 3 0.18Polypedilum 29 0.68 6 0.17 194 3.24Potthastia Longimana Gr. 5 0.18 8 0.54Pseudosmittia 54 1.64Rheotanytarsus 16 0.49 32 1.11 8 0.54 86 1.44Stempellinella 13 0.33Thienemanniella 13 0.33 5 0.18Thienemannimyia Gr. 6 0.17 16 0.49 86 2.96 8 0.54 11 0.18Tvetenia discoloripes grp. 15 0.34 6 0.17Tvetenia bavarica grp. 54 0.9TOTAL - CHIRONOMIDAE 117 2.71 65 1.66 215 6.58 204 7.02 527 35.06 473 7.91GRAND TOTAL 4331 100 3902 100 3271 100 2911 100 1504 100 5983 100

SERCD2 (2002) SERCD2 (2003) SERCD2 (2004) SERCD2 (2005)

Gastropoda

Insecta

Oligochaeta

SERCD2 (1999) SERCD2 (2000)

59

Appendix 2-10 – WSII and WY RIVPACS scores for WDEQ/WQD and SERCD stations on the North Platte River by segment.

Index Score Narrative Rating Index Score Narrative Rat ingSR12 1997 78.8 Full-support 0.99 Full-supportSR24 1996 77.9 Full-support 0.99 Full-supportWB5 1997 74.6 Full-support 0.93 Full-supportWB29 1997 64.5 Full-support

SERCD1 1999 60.3 Full-support 0.73 IndeterminateSERCD1 2000 52.0 Full-support 0.60 Partial/Non-supportSERCD1 2002 35.3 Indeterminate 0.47 Partial/Non-supportSERCD1 2003 38.1 Indeterminate 0.40 Partial/Non-supportSERCD1 2004 42.7 Indeterminate 0.47 Partial/Non-supportSERCD1 2005 45.6 Indeterminate 0.53 Partial/Non-supportWB220 2004 46.2 Indeterminate 0.56 Partial/Non-supportSERCD2 1999 65.1 Full-support 0.74 IndeterminateSERCD2 2000 53.0 Full-support 0.60 Partial/Non-supportSERCD2 2002 47.5 Indeterminate 0.53 Partial/Non-supportSERCD2 2003 48.1 Indeterminate 0.60 Partial/Non-supportSERCD2 2004 49.1 Indeterminate 0.66 IndeterminateSERCD2 2005 48.4 Indeterminate 0.47 Partial/Non-support

WBI21 1997 61.9 Full-supportWB174 2002 41.4 Indeterminate 0.47 Partial/Non-support

WB175 2002 31.5 Partial/Non-support 0.53 Partial/Non-supportWB181 2002 29.1 Partial/Non-support 0.27 Partial/Non-supportWB176 2002 29.4 Partial/Non-support 0.40 Partial/Non-support

3 NGP193 2004 45.5 Full-support 0.27 Partial/Non-support

NGP151 2002 46.4 Full-support 0.78 IndeterminateNGP150 2002 62.8 Full-support 0.78 IndeterminateWHP36 2002 54.8 Full-support 0.53 Partial/Non-supportWHP35 2002 64.4 Full-support 0.67 IndeterminateWHP34 2002 53.0 Full-support 0.78 IndeterminateWHP33 2002 58.0 Full-support 0.56 Partial/Non-supportWHP32 2002 63.2 Full-support 0.56 Partial/Non-support

2

4

Station ID YearSegment

Insufficient Information

Insufficient Information

WSII RIVPACS

1

60

Appendix 2-11 – WSII metric values, scores and site ratings for WDEQ/WQD stations on the North Platte River above Seminoe Reservoir.

SR12 NORTH PLATTE RIVER-PIKE POLE (1997)

Metric Metric Scoring Formulae

5th or 95th %-ile (as per

formula) Metric Value Metric Score

Ephemeroptera taxa 100*X / 95th%ile 10 6 60.0

Trichoptera taxa 100*X / 95th%ile 12 11 91.7

Plecoptera taxa 100*X / 95th%ile 9 6 66.7

% non-insects 100*(55-X) / (55-5th%ile) 0 3.35 93.9

% Trichoptera (less Hydropsychidae) (% w ithin community) 100*X / 95th%ile 41.5 37.95 91.4

Scraper taxa 100*X / 95th%ile 8 8 100.0

BCICTQa 100*(102.9-X) / (102.9-5th%ile) 48.1 66.46 66.5

Semi-voltine taxa (less semivoltine Coleoptera) 100*X / 95th%ile 5 3 60.0

>68.2 Full-Support; 45.5-68.2 Indeterminate; <45.5 Partial/Non-Support Index score 78.8

90% CONFIDENCE INTERVAL: ±6.4 Rating Full-support

SR24 NORTH PLATTE RIVER-CORRAL CREEK (1996)







% Plecoptera 100*X / 95th%ile 22.3 1.29 5.8

% non-insects 100*(64-X) / (64-5th%ile) 0.4 10.66 83.9

% Trichoptera (less Hydropsychidae) (% w ithin Trichoptera) 100*X / 95th%ile 100 51.65 51.7

% collector-gatherers 100*(96-X) / (96-5th%ile) 20.3 27.63 90.3

% scrapers 100*X / 95th%ile 38.6 35.54 92.1

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 4.04 66.6



90% CONFIDENCE INTERVAL: ±4.8 Rating Full-Support

WB5 NORTH PLATTE RIVER-TREASURE ISLAND (1997)











% scrapers 100*X / 95th%ile 38.6 19.4 50.3

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 3.62 73.1




WB29 NORTH PLATTE RIVER-ABOVE SAGE CREEK (1997)










% collector-gatherers 100*(96-X) / (96-5th%ile) 20.3 36 79.3

% scrapers 100*X / 95th%ile 38.6 16 41.5

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 4.9 53.1




SO

UT

HE

RN

RO

CK

IES

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

61

Appendix 2-11 (cont.) – WSII metric values, scores and site ratings for WDEQ/WQD stations on the North Platte River above Seminoe Reservoir.

WB220 NORTH PLATTE RIVER-THE OLD BOB PLACE (2004)











% scrapers 100*X / 95th%ile 38.6 4.97 12.9

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 5.69 40.8



90% CONFIDENCE INTERVAL: ±4.8 Rating Indeterminate

WBI21 NORTH PLATTE RIVER-SAVAGE MEADOWS (1997)











% scrapers 100*X / 95th%ile 38.6 11.83 30.6

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 3.93 68.3




WB174 NORTH PLATTE RIVER-FT. STEELE CANYON (2002)











% scrapers 100*X / 95th%ile 38.6 15.93 41.3

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 5.95 36.7




WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

62

Appendix 2-12 – WSII metric values, scores and site ratings for SERCD1 on the North Platte River above Seminoe Reservoir.

SERCD1 NORTH PLATTE RIVER AT MCKEAL MEADOWS (1999)











% scrapers 100*X / 95th%ile 38.6 13.84 35.9

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 4.75 55.5















% scrapers 100*X / 95th%ile 38.6 14.86 38.5

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 6.03 35.5















% scrapers 100*X / 95th%ile 38.6 18.41 47.7

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 6.68 25.3















% scrapers 100*X / 95th%ile 38.6 11.65 30.2

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 6.78 23.8




WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

63

Appendix 2-12 (cont.) – WSII metric values, scores and site ratings for SERCD1 on the North Platte River above Seminoe Reservoir.












% scrapers 100*X / 95th%ile 38.6 7.08 18.3

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 6.45 28.9















% scrapers 100*X / 95th%ile 38.6 19.11 49.5

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 7.01 20.2




WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

64

Appendix 2-13 – WSII metric values, scores and site ratings for SERCD2 on the North Platte River above Seminoe Reservoir.

SERCD2 NORTH PLATTE RIVER AT SAVAGE RANCH (1999)











% scrapers 100*X / 95th%ile 38.6 14.26 36.9

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 4.06 66.3












% non-insects 100*(64-X) / (64-5th%ile) 0.4 3 95.9



% scrapers 100*X / 95th%ile 38.6 13.76 35.6

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 5.77 39.5















% scrapers 100*X / 95th%ile 38.6 20.07 52.0

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 5.35 46.1















% scrapers 100*X / 95th%ile 38.6 23.47 60.8

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 6.94 21.3




WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

65

Appendix 2-13 (cont.) – WSII metric values, scores and site ratings for SERCD2 on the North Platte River above Seminoe Reservoir.












% scrapers 100*X / 95th%ile 38.6 12.36 32.0

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 6.29 31.4















% scrapers 100*X / 95th%ile 38.6 12.23 31.7

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 6.51 28.0




WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

66

Appendix 3-1 – Physicochemical results at WDEQ/WQD stations on the North Platte River between Seminoe Reservoir and Casper, Wyoming.

WB175 WB181 WB179 WB176 WB177 WB178Date 9/18/02 9/24/02 10/22/02 10/22/02 10/22/02 10/22/02Time 14:17 9:20 17:10 9:05 14:27 14:40Temperature C 16.4 15.5 9.9 7.2 6.1 7.5pH 9.1 8.5 8.8 8.7 8.6 8.5Conductivity (uS/cm) 495 492 500 555 534 540Dissolved Oxygen (mg/L) 10.5 8.3 10.9 8.5 10.0 9.9Turbidity (NTU) 7.1 20.1 5.1 3.7 4.1 3.2TSS (mg/L) 5 8 4 <2 <2 3Alkalinity (mg/L as CaCO3) 120 150 140 140 140 150Sulfate (mg/L) 124 117 123 144 152 141Chloride (mg/L) 10 9 10 11 12 16Nitrate (mg/L as N) <0.1 0.1 <0.1 <0.1 <0.1 <0.1Total Phosphorus (mg/L) <0.1 <0.1 <0.1 <0.1 <0.1 <0.1Total Hardness (mg/L as CaCO3) 192 196 204 216 224 232Total Selenium (ug/L) NM NM <5 6 <5 <5Total Copper (ug/L) NM NM <10 <10 <10 <10Total Cadmium (ug/L) NM NM <1 <1 <1 <1Total Lead (ug/L) NM NM <5 <5 <5 <5Total Mercury (ug/L) NM NM <1 NM NM NMColor None Gray None None None NoneSheen None None None None None NoneOdor None None None None None NoneDischarge (cfs) 546 75 501 ~501 ~501 ~501

NM = Not Measured

67

Appendix 3-2 – Qualitative habitat assessment, biological indicators and substrate composition for WDEQ/WQD stations on the North Platte River between Seminoe Reservoir and Casper, Wyoming.

STATION ID WB175 WB181 WB176EcoregionStream Type (Reference=R, Non-Reference=NR) NR NR NR

Habitat Parameters (Max. Score)Epifaunal Substrate/Available Cover (20) 19 16 11Embeddedness (20) 18 18.5 19Velocity/Depth (20) 20 17 18Channel Flow Status (20) 17 19 15Sediment Deposition (20) 19 20 18Frequency of Riffles (20) 19 6 18Channelization/Alteration (20) 19 19 19Bank Vegetation Protection (10) 9.5 10 7.5Bank Stability (10) 9.5 10 7.5Riparian Vegetative Zone Width (10) 7 9.5 4.5HABITAT ASSESSMENT TOTAL >10% Riffle/Run (170 a possible) 157 145 137.5HABITAT ASSESSMENT (Percent of Maximum Score) 92.4 85 .3 80.9

PERCENT COMPARABILITY TO MEAN REFERENCE HABITAT CONDITION (Wyoming Basin = b72.9)

126.7 117 111

Biological Indicators*Periphyton 3 2 2Filamentous Algae 3 2 3Rooted Macrophytes 3 3 2Floating Macrophytes 1 0 0Fish 2 0 0Slimes 0 0 0

Substrate CompositionCobble 60.1 65.0 57.5Coarse Gravel 18.0 8.8 22.5Fine Gravel 7.4 8.1 14.4Sand 4.4 10.0 5.6SiltClay-Hard Pack (solid, slick)Organic (f ine, black, odor)Boulder 0.1 8.1

Weighted Embeddedness 94.5 98.1 99.0

Mean Water Velocity (ft/sec) 3.3 3.1 2.3


Wyoming Basin

a Large river habitat assessmentb See Table 2

68

Appendix 3-3 – Summary of macroinvertebrate collection results at WDEQ/WQD stations on the North Platte River between Seminoe Reservoir and Casper, Wyoming.

Taxon A bundance % C o mposit ion A bundance % C omposit io n A bundan ce % C omposit ion

Hirudinea Hirudinea 18 0.19

Turbellaria Turbellaria 81 0.74 556 5.87

Nematoda Nematoda 61 0.56 81 0.39 36 0.38

Imm. Tubificid w/ cap setae 182 1.66 161 1.7Imm. Tubificid w/o cap setaeNais 448 4.73Nais bretscheri 101 0.92Ophidonais serpentina 90 0.95

Physidae 215 1.03Stagnicola 27 0.13

Gammarus 54 0.57Hyallela 242 1.16

Hydrachnida Acari 605 5.52 27 0.13

TOTAL - NON-INSECTS 1030 9.4 592 2.83 1363 14.39Petrophila 108 1.14TOTAL - LEPIDOPTERA 108 1.14Acentrella 161 1.7Baetis tricaudatus 3369 30.75 888 4.24 1094 11.55Ephemerella 161 1.47Heptagenia/Nixe 18 0.19Leptophlebidae 20 0.18Tricorythodes minutus 1574 14.37 135 0.65 2349 24.81TOTAL - EPHEMEROPTERA 5124 46.77 1023 4.89 3622 38.25Hesperoperla pacifica 40 0.37Isoperla 108 1.14TOTAL - PLECOPTERA 40 0.37 108 1.14Cheumatopsyche 121 1.11Hydropsyche 141 1.29 5649 26.99 2905 30.68Hydroptila 141 1.29 108 0.52 197 2.08Oecetis 466 4.92TOTAL - TRICHOPTERA 403 3.68 5757 27.51 3568 37.68Microcylloepus 20 0.18Optioservus 404 3.69TOTAL - COLEOPTERA 424 3.87Ceratopogoninae 27 0.13Hemerodromia 18 0.19Simulium 666 6.08 7989 38.17 341 3.6TOTAL - DIPTERA 666 6.08 8016 38.3 359 3.79Cardiocladius 484 2.31Chironomidae-pupae 202 1.84 350 1.67Cricotopus bicinctus 673 3.22Cricotopus (cricotopus) 1480 7.07Cricotopus (isocladius) 673 3.22Cricotopus trifascia 847 7.73 968 4.62 36 0.38Dicrotendipes 18 0.19Eukiefferiella 81 0.74 484 2.31Eukiefferiella devonica 242 2.21 161 0.77Lopescladius 36 0.38Micropsectra 20 0.18Microtendipes 81 0.74 144 1.52Nanocladius 20 0.18Orthocladius 54 0.26 108 1.14Orthocladius rivularum 20 0.18Paratanytarsus 161 0.77Paratendipes 27 0.13Polypedilum 20 0.18Potthastia 81 0.74Synorthocladius 20 0.18Thienemannimyia Gr. 20 0.18 27 0.13Tvetenia 1614 14.73TOTAL - CHIRONOMIDAE 3268 29.83 5542 26.48 342 3.61GRAND TOTAL 10955 100 20930 100 9470 100

Insecta

Amphipoda

WB181 (2002)

Gastropoda

Olig

ocha

eta

WB176 (2002)WB175 (2002)

69

Appendix 3-4 – WSII metric values, scores and site ratings for WDEQ/WQD stations on the North Platte River between Seminoe Reservoir and Casper, Wyoming.

WB175 NORTH PLATTE RIVER-MIRACLE MILE (2002)











% scrapers 100*X / 95th%ile 38.6 3.66 9.5

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 5.74 40.0



90% CONFIDENCE INTERVAL: ±4.8 Rating Partial/Non-Support

WB181 NORTH PLATTE RIVER-FREMONT CANYON (2002)







% Plecoptera 100*X / 95th%ile 22.3 0 0.0




% scrapers 100*X / 95th%ile 38.6 1.01 2.6

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 5.37 45.8




WB176 NORTH PLATTE RIVER-BELOW BATES CREEK (2002)











% scrapers 100*X / 95th%ile 38.6 1.44 3.7

HBI 100*(8.3-X) / (8.3-5th%ile) 1.9 5.57 42.7




WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

WY

OM

NG

BA

SIN

70

Appendix 4-1 – Physicochemical results at WDEQ/WQD stations on the North Platte River between Casper, Wyoming and Glendo Reservoir.

CASPER1 CASPER2 DOUG1 DOUG2 NGP193Date 10/2/03 10/2/03 10/2/03 10/2/03 10/7/04Time 11:50 11:30 14:40 14:10 11:10Temperature C 13.4 14.1 17.2 17.1 15.6pH 8.6 8.3 8.9 8.9 8.9Conductivity (uS/cm) 745 1042 862 856 830Dissolved Oxygen (mg/L) 8.6 8.4 9.1 9.2 8.8Turbidity (NTU) NM NM NM NM 5.1TSS (mg/L) 4 5 6 6 6Alkalinity (mg/L as CaCO3) NM NM NM NM 152Sulfate (mg/L) NM NM NM NM 257Chloride (mg/L) NM NM NM NM 20Nitrate (mg/L as N) NM NM NM NM <0.1Total Phosphorus (mg/L) NM NM NM NM <0.1Total Hardness (mg/L as CaCO3) NM NM NM NM 280Total Ammonia (mg/L) <0.1 <0.1 <0.1 <0.1 NMBiological Oxygen Demand (mg/L) <1 <1 <1 <1 NMFecal Coliform (cfu/100 mL) 37 1934 7 17 NME. coli (cfu/100 mL) 38 1562 11 5 5Color None Lt. Yellow None None NoneSheen None None None None NoneOdor None None None None NoneDischarge (cfs) ~501 ~513 ~513 ~514 ~530

NM = Not Measured

71

Appendix 4-2 – Qualitative habitat assessment, biological indicators and substrate composition for WDEQ/WQD station NGP193 on the North Platte River between Casper, Wyoming and Glendo Reservoir.

STATION ID NGP193

Ecoregion Northwestern Great Plains

Stream Type (Reference=R, Non-Reference=NR) NR

Habitat Parameters (Max. Score)Epifaunal Substrate/Available Cover (20) 16Embeddedness (20) 11Velocity/Depth (20) 17Channel Flow Status (20) 15Sediment Deposition (20) 17Frequency of Riffles (20) 17Channelization/Alteration (20) 16Bank Vegetation Protection (10) 10Bank Stability (10) 10Riparian Vegetative Zone Width (10) 8HABITAT ASSESSMENT TOTAL >10% Riffle/Run (170 a possible) 137HABITAT ASSESSMENT (Percent of Maximum Score) 80.6a Large river habitat assessment

Biological Indicators*Periphyton 2Filamentous Algae 2Rooted Macrophytes 1Floating Macrophytes 0Fish 2Slimes 0

Substrate CompositionCobble 2.5Coarse Gravel 14.4Fine Gravel 33.8Sand 39.4Silt 10.0Clay-Hard Pack (solid, slick)Organic (f ine, black, odor)Boulder

Weighted Embeddedness 40.0

Mean Water Velocity (ft/sec) 0.85

NM = Not Measured


72

Appendix 4-3 – Summary of macroinvertebrate collection results at WDEQ/WQD station NGP193 on the North Platte River between Casper, Wyoming and Glendo Reservoir.

Taxon A b und ance % C o mp o si t io n

Nematoda Nematoda 81 1.86

Chaetogaster 32 0.73Imm. Tubificid w/ cap setae 57 1.31Imm. Tubificid w/o cap setae 347 7.95Nais 1364 31.25Ophidonais serpentina 97 2.22Prostoma 347 7.95

Gastropoda Physidae 8 0.18

Hydrachnida Acari 16 0.37

TOTAL - NON-INSECTS 2349 53.81Petrophila 8 0.18TOTAL - LEPIDOPTERA 8 0.18Acentrella 57 1.31Centroptilum 8 0.18Diphetor hageni 40 0.92Ephemerella 16 0.37Tricorythodes minutus 734 16.82TOTAL - EPHEMEROPTERA 855 19.59Cheumatopsyche 105 2.41Culoptila 16 0.37Hydropsyche 65 1.49Hydroptila 32 0.73Psychomyia 16 0.37Oecetis 16 0.37TOTAL - TRICHOPTERA 250 5.73Hemerodromia 8 0.18Simulium 48 1.1TOTAL - DIPTERA 56 1.28Chironomidae-pupae 89 2.04Cricotopus (cricotopus) 210 4.81Cryptochironomus 57 1.31Dicrotendipes 32 0.73Lopescladius 16 0.37Microtendipes 266 6.09Parakiefferiella 16 0.37Paratanytarsus 8 0.18Phaenopsectra 32 0.73Polypedilum 97 2.22Rheocricotopus 8 0.18Thienemannimyia Gr. 8 0.18Tvetenia 8 0.18TOTAL - CHIRONOMIDAE 847 19.4GRAND TOTAL 4365 100

Olig

ocha

eta

NGP193 (2004)

Insecta

73

Appendix 4-4 – WSII metric values, scores and the rating for WDEQ/WQD station NGP193 on the North Platte River between Casper, Wyoming and Glendo Reservoir.

NGP193 NORTH PLATTE RIVER-ANDERSON DAIRY (2004)






Total taxa 100*X / 95th%ile 42 34 81.0


% Ephemeroptera (less Baetidae) (% w ithin community) 100*X / 95th%ile 54.4 17.19 31.6

% collector-gatherers 100*(98.5-X) / (98.5-5th%ile) 12.6 83.9 17.0

HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 7.12 50.7


90% CONFIDENCE INTERVAL: ±4.8 Rating full

PLA

INS

74

Appendix 5-1 – Physicochemical results at WDEQ/WQD stations on the North Platte River between Glendo Reservoir and the Wyoming/Nebraska stateline.

NGP151 NGP150 WHP36 GUERN1 WHP35 WHP34 WHP33 WHP32Date 10/9/02 10/9/02 10/8/02 6/18/03 8/30/02 8/22/02 8/22/02 8/22/02Time 13:40 9:00 9:55 11:05 14:50 12:40 12:20 10:10Temperature C 15.5 9.5 11.5 20.0 22.9 21.0 20.3 18.4pH 8.8 8.3 8.6 8.6 8.4 8.2 8.2 8.1Conductivity (uS/cm) 748 743 645 NM 714 679 669 667Dissolved Oxygen (mg/L) 11.9 8.7 10.2 8.9 8.6 8.4 8.6 8.6Turbidity (NTU) 6.8 2.4 0.9 NM 3.6 4.9 3.8 8.3TSS (mg/L) 4 3 2 4 4 6 7 18Alkalinity (mg/L as CaCO3) 160 180 160 NM 180 190 210 200Sulfate (mg/L) 207 210 166 NM 173 168 178 178Chloride (mg/L) 16 15 13 NM 13 33 16 16Nitrate (mg/L as N) 0.1 0.1 0.2 NM 0.4 1.0 1.0 1.2Total Phosphorus (mg/L) <0.1 <0.1 <0.1 NM <0.1 <0.1 <0.1 <0.1Total Hardness (mg/L as CaCO3) 256 268 236 NM 255 263 263 270Biological Oxygen Demand (mg/L) NM NM NM 2 NM <1 <1 NMTotal Arsenic (ug/L) NM NM NM NM NM <5 <5 NMTotal Selenium (ug/L) NM NM NM NM NM <5 <5 NMTotal Ammonia (mg/L) NM NM NM 0.1 NM <0.1 <0.1 NMFecal Coliform (cfu/100 mL) NM NM NM 42 NM *66 *47 NMSheen None None None None None None None NoneColor Lt. Gray None None None None None Lt. Green Brow nOdor None None None None None None None NoneDischarge (cfs) 30 30 29 941 255 359 364 402

NM = Not Measured

*5 sample 30-day geometric mean collected from 9/6/02 to 9/26/02

75

Appendix 5-2 – Qualitative habitat assessment, biological indicators and substrate composition for WDEQ/WQD stations on the North Platte River between Glendo Reservoir and the Wyoming/Nebraska stateline.

Station ID NGP151 NGP150 WHP36 WHP35 WHP34 WHP33 WHP32

Ecoregion

Stream Type (Reference=R, Non-Reference=NR) NR NR NR NR NR NR NR

Habitat Parameters (Max. Score)Epifaunal Substrate/Available Cover (20) 17 16 5 15 16.5 12 11Embeddedness (20) 19 18 18 18 18.5 18 17Velocity/Depth (20) 17 16 16 16 17 15 18Channel Flow Status (20) 8 7 8 13 13 15 14Sediment Deposition (20) 18 15 6 15 11.5 15 11Frequency of Riffles (20) 17 19 16 14 16 16 17Channelization/Alteration (20) 19 19 19 19 18.5 19 18Bank Vegetation Protection (10) 10 9.5 4 5.5 6.5 7.5 3.5Bank Stability (10) 10 9.5 5 5.5 6.5 8 2.5Riparian Vegetative Zone Width (10) 5.5 9.5 7 7.5 9 7.5 7.5HABITAT ASSESSMENT TOTAL >10% Riffle/Run (170 a possible) 140.5 138.5 104 128.5 133 133 119.5HABITAT ASSESSMENT (Percent of Maximum Score) 82.6 81 .5 61.2 75.6 78.2 78.2 70.3a Large river habitat assessment

Biological Indicators*Periphyton 2 2 2 2 2 2 2Filamentous Algae 4 3 1 2 2 3 2Rooted Macrophytes 1 1 1 1 0 1 0Floating Macrophytes 0 0 0 0 0 0 0Fish 2 2 2 2 2 2 2Slimes 0 0 0 0 0 0 0

Substrate CompositionCobble 35.0 54.0 3.0 1.9Coarse Gravel 13.8 16.5 41.0 26.9 31.9 65.0Fine Gravel 48.8 12.8 22.5 48.6 46.9 24.4 13.8Sand 2.5 8.6 77.5 4.6 26.3 39.1 18.8Silt 2.8 4.6Clay-Hard Pack (solid, slick)Organic (f ine, black, odor)Boulder 8.1

Weighted Embeddedness 99.4 99.9 **100 100.0 99.9 99.6 100.0

Mean Water Velocity (ft/sec) 1.1 1.4 1.2 1 1.4 1.4 2.03

Northwestern Great Plains

Western High Plains


NM = Not Measured

**Value has little meaning since substrate is sand-dominated.

76

Appendix 5-3 – Summary of macroinvertebrate collection results at WDEQ/WQD stations on the North Platte River between Glendo Reservoir and the Wyoming/Nebraska stateline.

Taxon A b undance % C omp osi t io n A b undance % C o mpo si t ion A b undan ce % C o mpo si t ion A b und ance % C omp osi t io n A b und ance % C o m po si t ion A b undance % C o mpo si t ion A bund ance % C o mp osi t io n

Turbellaria Turbellaria 27 0.21 269 1.69

Nematoda Nematoda 215 1.63 27 0.17 780 5.12 30 0.54 148 6.36 192 8.36 14 2.19

Branchiobdellida 54 0.34Imm. Tubificid w/o cap setae 54 0.34 31 1.33Limnodrilus hoffmeisteri 3 0.47

Ferrissia 511 3.88Gyralus 27 0.21Helisoma 81 0.62Physidae 1372 10.43

Crangonyx 242 1.84 27 0.17Gammarus 27 0.18

Hydrachnida Acari 430 3.27 404 2.54

TOTAL - NON-INSECTS 2905 22.08 835 5.24 807 5.3 30 0.54 179 7.7 192 8.36 17 2.66Petrophila 81 0.51 27 0.18 5 0.22 5 0.22TOTAL - LEPIDOPTERA 81 0.51 27 0.18 5 0.22 5 0.22Gomphidae 10 0.18TOTAL - ODONATA 10 0.18Acentrella 108 0.82 1560 9.79 2475 16.25 1110 20.05 578 24.85 303 13.19 124 19.41Baetis tricaudatus 646 4.91 1775 11.14 135 0.89Camelobaetidius 135 0.89 71 1.28 40 1.72 10 0.44 11 1.72Centroptilum 5 0.22Choroterpes 54 0.41 3847 24.15 2071 13.6 91 1.64 3 0.47Ephemerella inermis/infrequens 377 2.37Ephoron 10 0.18 1 0.16Fallceon quilleri 27 0.17 511 3.36 252 4.55 108 4.64 116 5.05 59 9.23Isonychia 27 0.17 10 0.18 7 1.1Lachlania 1 0.16Rhithrogena 323 2.12 494 8.92 76 3.27 25 1.09 18 2.82Tricorythodes minutus 3524 26.79 538 3.38 2313 15.19 1776 32.08 511 21.97 852 37.08 178 27.86TOTAL - EPHEMEROPTERA 4332 32.93 8151 51.17 7963 52.29 3814 68.88 1313 56.45 1311 57.05 402 62.91Perlodidae-early instar 188 1.18 54 0.35TOTAL - PLECOPTERA 188 1.18 54 0.35Cheumatopsyche 2851 21.67 1291 8.11 995 6.53 202 3.65 22 0.95 10 0.44Glossosomatidae 20 0.36Hydropsyche 1399 10.63 3685 23.14 350 2.3 999 18.04 67 2.88 40 1.74 9 1.41Hydroptila 108 0.68 10 0.18 14 0.6 45 1.96 16 2.5Nectopsyche 5 0.22 3 0.47Ochrotrichia 108 0.82Oecetis 108 0.68 135 0.89 9 0.39 10 0.44 1 0.16Protoptila 27 0.17 27 0.18 20 0.36 5 0.21 1 0.16TOTAL - TRICHOPTERA 4358 33.13 5219 32.77 1507 9.9 1251 22.59 117 5.03 110 4.79 30 4.69Zaitzevia 27 0.17TOTAL - COLEOPTERA 27 0.17Ceratopogoninae 20 0.36 5 0.22 1 0.16Empididae 30 0.54Hemerodromia 404 3.07 108 0.68 27 0.18 22 0.95 1 0.16Ptychoptera 5 0.21Simulium 780 5.93 296 1.86 2529 16.61 40 0.72 81 3.48 61 2.65 57 8.92TOTAL - DIPTERA 1184 9 404 2.54 2556 16.78 90 1.63 108 4.64 66 2.87 59 9.23Brillia 1 0.16Cardiocladius 5 0.21 20 0.87Chironomidae-pupae 81 0.51 40 0.72 126 5.42 86 3.74 42 6.57Chironomus 20 0.87Cladotanytarsus 27 0.18 30 0.54 5 0.21 1 0.16Cricotopus bicinctus 5 0.21 1 0.16Cricotopus (cricotopus) 27 0.21 61 1.1 227 9.88 3 0.47Cricotopus trifascia 188 1.43 135 0.85 30 0.54 377 16.21 126 5.48 62 9.7Cryptochironomus 10 0.18Dicrotendipes 25 1.09Eukiefferiella 1 0.16Glyptotendipes 5 0.22Lopescladius 457 2.87 1964 12.9 20 0.36 5 0.21 5 0.22 3 0.47Microtendipes 27 0.21Nanocladius 15 0.62Phaenopsectra 30 1.31 1 0.16Polypedilum 215 1.35 54 0.35 10 0.18 5 0.21 30 1.31 7 1.1Rheotanytarsus 27 0.21 20 0.36 18 0.77Robackia 269 1.77 22 0.95 3 0.47Tanytarsus 1 0.16Thienemanniella Gr. 5 0.22 3 0.47Thienemannimyia Gr. 50 0.9 31 1.33 15 0.62 1 0.16Tvetenia 108 0.82 135 0.85 71 1.28 5 0.21 5 0.22 1 0.16TOTAL - CHIRONOMIDAE 377 2.87 1023 6.42 2314 15.2 342 6.18 604 25.97 614 26.72 131 20.5GRAND TOTAL 13156 100 15928 100 15228 100 5537 100 2326 100 2298 100 639 100

Gastropoda

Insecta

WHP32 (2002)

Amphipoda

WHP36 (2002) WHP33 (2002)WHP34 (2002)WHP35 (2002)

Oligochaeta

NGP151 (2002) NGP150 (2002)

77

Appendix 5-4 – WSII metric values, scores and site ratings for WDEQ/WQD stations on the North Platte River between Glendo Reservoir and the Wyoming/Nebraska stateline.

NGP151 NORTH PLATTE RIVER-BELOW GLENDO DAM (2002)










HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 6.63 61.6



NGP150 NORTH PLATTE RIVER-CASSA (2002)










HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 5.09 95.8



WHP36 NORTH PLATTE RIVER-WENDOVER (2002)










HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 5.59 84.7



WHP35 NORTH PLATTE RIVER-ABOVE RAWHIDE CREEK (200 2)










HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 4.91 99.8



PLA

INS

PLA

INS

PLA

INS

PLA

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Appendix 5-4 (cont.) – WSII metric values, scores and site ratings for WDEQ/WQD stations on the North Platte River between Glendo Reservoir and the Wyoming/Nebraska stateline.

WHP34 NORTH PLATTE RIVER-ABOVE TORRINGTON WWTF (2 002)










HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 5.22 92.9



WHP33 NORTH PLATTE RIVER-BELOW TORRINGTON WWTF (2 002)










HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 5.81 49.8



WHP32 NORTH PLATTE RIVER-HUNTON MEADOWS (2002)










HBI 100*(9.4-X) / (9.4-5th%ile) 4.9 5.36 89.8



PLA

INS

PLA

INS

PLA

INS

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