South Fork Republican River and Hale Ponds Fish Kill ... · downstream of Station 1. This reach of...

South Fork Republican River and Hale Ponds Fish Kill Incident June 5-6, 2015

Aaron Berscheid – District Wildlife ManagerPaul Foutz – Southeast Native Aquatic Species Biologist

Colorado Parks and WildlifeSoutheast Region4255 Sinton Road

Colorado Springs, CO 80907719-227-5200

Background

A fish kill was investigated by the Colorado Parks and Wildlife (CPW) on South Fork Republican River downstream of Bonny Reservoir and upstream of the Kansas state line (see Figure 1 & 2). CPW was first notified of this event on the morning of 06/08/2015 by , a landowner west of Yuma County Road LL.5, and just north of the South Fork of the Republican River. stated that between the evening of 06/05/2015 overnight into the morning of 06/06/2015, two effluent retention ponds belonging to Five Star Feeders cattle lot had broken their levees due to a large rain event. The flow from those broken levees crossed

property to the south of Five Star Feeders, and entered into the South Fork of the Republican River (S. Republican River) around the area of Yuma County Road LL.5, where the river crosses underneath the road. On 06/08/2015 DWM Berscheid notified CPW Area Wildlife Manager Frank McGee of the incident, and AWM McGee notified Colorado Department of Public Health and Environment. AWM McGee also notified CPW Native Aquatic Species Biologist Paul Foutz of the incident.

Methods and Materials

This incident was investigated utilizing guidance from the Colorado Parks and Wildlife Administrative Directive W-5, “Investigating and Reporting Natural Resource Injury Due to Known or Suspected Pollution of Water in Colorado”.

The upper terminus of the impacted reach (fish kill zone) of the South Fork Republican River was considered to be approximately Yuma County Road LL.5 (Photo 1). At this point, three areas in close vicinity to the bridge were located where the effluent flowed into the mainstem of the river. The lower terminus of the impacted reach (kill zone) of the South Fork Republican River was considered to be at the Kansas state line based on CPW jurisdictional restrictions. Reports from Kansas Department of Wildlife, Parks and Tourism staff indicated the kill zone continued into Kansas at least north of St. Francis, Kansas. Hale Ponds on South Republican State Wildlife Area is fed by flows coming off of South Fork Republican River and was also impacted by the event (specifically Hale Pond #1). In addition to Hale Pond #1, the event impacted approximately 14,180 stream miles of the South Fork Republican River in Colorado (calculated by CPW GIS staff).

On June 8, 2015, an initial sampling response was conducted by CPW District Wildlife Manager Aaron Berscheid. DWM Berscheid visited the site where the effluent flow entered the S. Republican River. DWM Berscheid’s initial investigation was to solely to determine if the effluent flow did or did not have an impact on the health of the riparian area affected, including any wildlife or fish therein. DWM Berscheid noted a visible increase in turbidity of the water where the flow entered the river, and took pictures (Photos 1-3) at that location approximately where the S. Republican River crosses under Yuma County Road LL.5. DWM Berscheid then went to Hale Ponds (a part of the South Republican State Wildlife Area, downstream of the upper terminus of the effluent flow) and looked at the ponds, as well as the river bank of the S. Republican River near the diversion inlet to the Hale Ponds . DWM Berscheid noted dead fish in

the furthest west pond (Hale Pond #1), and along the river bank. DWM Berscheid took pictures of some of the dead fish located, as well as collected all the fish that he could from the south shoreline of Pond #1 with a dip net. Fish that were collected on June 8, 2015 were preserved in mason jars with isopropyl alcohol, sealed, and labeled (those fish were identified and measured on June 12, 2015 with the assistance of Foutz) .

Further evaluation of the event’s impact was conducted over several days from June 9th to June 11th, 2015. S. Republican River was visually inspected at multiple sites on June 9th, and Hale Pond #1 was inspected over multiple days for signs of post mortem fish.

On June 9th, 2015; four sampling sites were identified between the upper terminus point and the state line to estimate and evaluate the minimum number of fishes killed by the event. Each site was visually inspected through a consistent method using 4 CPW staff members (DWM Berscheid, Foutz, and 2 CPW biological technicians). Fishes were identified to species when possible (some were is very poor condition to the length of time between the kill event and the kill investigation. Fish counts are included in Exhibit C below. Water quality data (pH, DO and water temperature) were collected at each of the sites using a Hach water quality test kit. All water quality test were conducted by Foutz. Water quality results are included in the notes section of the fish counting record for each site. A water quality test on Hale Pond #1 was also conducted on this day.

A brief description of the four stations as well as the post mortem fish collected is as follows:

Station 1 (RRSpil1): 300 foot station (Photo 5 & 6) was located 150 feet downstream from the last of 3 spill source points into the river. This reach of stream is classified as a run. Post mortem fish collected at this site included 12 species and 159 fishes.

Station 2 (RRSpil2): 300 foot station (Photo 7 & 8) located approximately 2.3 miles downstream of Station 1. This reach of stream is classified as a run. Post mortem fish collected at this site included 12 species and a total of 140 fishes.

Station3 (RRSpil3): 300 foot station (Photo 9 & 10) located approximately 4.7 miles downstream of Station 2. This reach of stream is classified as a run. Post mortem fish collected at this site included 7 species and a total of 41 fishes .

Station 4 (RRSpil4): 300 foot station (Photo 11 & 12) located approximately 0.9 miles downstream of Station 3. This reach of stream is classified as a run. Post mortem fish collected at this site included 6 species and a total of 39 fishes .

One June 10th, starting at 6:00 PM collected fish from the west half of Hale Ponds Pond #1 from a belly boat. DWM Berscheid finished the collection at 6:45 PM. DWM Berscheid collected a total of 28 fish, but noted there were many more fish that were floating on the water’s surface on the east half of Pond #1. DWM Berscheid noted the condition of the fish were very deteriorated and found it difficult to collect the entire fish. Due to time constraints related to

nightfall and an impending storm, DWM Berscheid suspended his count for the evening. I took pictures around the east half to roughly document the amount of dead fish were still Pond #1 (All pictures not located within this report are on two DVD-R disks included with photo logs). The 28 fish that were collected were placed in a trash bag, sealed, and stored temporarily in an evidence chest freezer in the CPW office on the South Republican State Wildlife Area below Bonny Dam.

Fish samples were prepared for preservation and chain of custody documentation was initiated. Fish samples were packaged on ice and transported to the Colorado Parks and Wildlife Southeast Region Service Center to be securely stored. They are currently being held in CPW Area 14 evidence freezer.

On June 11th DWM Berscheid samples a control section of the S. Republican River upstream of the upper terminus of the affected area (Station 5 - RRSpil5). This 300 foot station (Photo 14 & 15) was located 0.8 miles upstream from the upper terminus. This reach of stream is classified as a run. No post mortem fish were found or collected at Station 5 (RRSpil5).

Later in the day of June 11th DWM Berscheid utilized a belly boat on Hale Pond #1 to finish his count of dead fish. DWM Berscheid floated the east side of Pond #1 counting all fish visible from the surface and called off counted fish and types to CPW Property Technician David Nicklos. Technician Nicklos recorded tallies of each fish I called. I started the count at 6:00 PM and completed the count at 7:45 PM.

Fish Kill Estimate

The total number of dead fish in the S. Republican River kill zone was determined by counting all dead fishes (379 fishes) in each of the four sampling stations (~1200’ total stream length), converting that to a linear density of dead fish and extrapolating that to the entire S. Republican River kill zone (94.75 fish per 300 feet = .32 fish/ft , multiplied by 42,180’ = 13,498 fish) for the affected river reach. Hale pond #1 is counted separately to a total of 1,389 fishes. The total fish kill number (13,498 + 1,389 = 14,887 total fishes) established is considered a minimum loss due to loss of dead fish that had washed downstream or had sunk to the river or pond bottom before assessments could be completed.

Results of Investigation

Incident reports were completed District Wildlife Manager Aaron Berscheid (Exhibit A and B).

A field investigation has revealed that the effluent flow that occurred June 5 overnight to the 6 was caused by a breach in effluent retention ponds on Five Star Feeders’ property due to a heavy rain event. The effluent flowed into the South Fork of the Republican River, downstream to the Colorado/Kansas border, and on into Kansas. The results of the investigation showed that fish were killed downstream of where the effluent flowed into the S. Republican River, but no dead fish were found upstream of where the effluent entered the S. Republican River. District

Wildlife Manager Aaron Berscheid was not made aware of the issue until the morning of June 8, 2015 by a landowner neighboring the S. Republican River. The same landowner showed District Wildlife Manager pictures of the flow and also pictures of Five Star Feeders rebuilding the dam. The combination of low dissolved oxygen levels and high ammonia concentrations in the river were likely contributing factors that lead to the fish mortality in the S. Republican River and Hale Ponds.

On June 9, 2015, while Colorado Parks and Wildlife personnel were conducting the field investigation, Five Star Feeders were meeting with the Colorado Department of Public Health and Environment (CDPHE). Both Colorado Parks and Wildlife and CDPHE collected water quality samples. CDPHE’s water quality samples and analysis (Exhibit D, page 6) of the samples were similar to the water quality samples collected and analyzed by Colorado Parks and Wildlife (Exhibit E). Melynda May, Water Quality Coordinator for Colorado Parks and Wildlife, analyzed the water quality samples. In Melynda’s analysis, she stated that a high concentration of ammonia related to animal waste, as well as, low levels of dissolved oxygen were likely the factors that led to the deaths of fish downstream of the upper terminus of the spill.

Discharge was obviously elevated by rain events on June 5th & 6th (Graph 1),

Graph 1. South Fork Republican River historic disharge data

Graph 2. South Fork Republican River gage height data.

Graph 3. South Fork Republican River stream discharge data.

Figure 1. South Fork Republican River incident map - street view

Figure 2. South Fork Republican River incident map - aerial view

Photo 1. S. Republican River at upper terminus

Photo 2. S. Republican River at upper end of terminus west of bridge at LL.5

Photo 3. S. Republican River at at upper end of terminus east of bridge at LL.5

Photo 4. S. Republican River at RRSpil1 upstream boundary looking at east edge of the 3rd river point source inlet

Photo 5. S. Republican River at RRSpil1 upstream boundary looking downstream

Photo 6. S. Republican River at RRSpil1 downstream boundary looking upstream


Photo 8. S. Republican River at RRSpil2 downstream boundary looking upstream

Photo 9. S. Republican River cross section at RRSpil2

Photo 11. S. Republican River at RRSpil3 downstream looking upstream

Photo 12. S. Republican River RRSpil4 upstream looking downstream

Photo 13. S. Republican River RRSpil4 downstream looking upstream

Photo 14. S. Republican River RRSpil5 upstream looking downstream

Photo 15. S. Republican River RRSpil5 downstream looking upstream

Photo 16. Hale Ponds Pond #1 dead fish eastern side of the pond

Photo 17. Hale Ponds Pond #1 dead fish on east end of pond

Photo 18. Hale Ponds Pond #1 dead fish swirl

Exhibit ASouth Republican River Fish Kill Investigation Report (ROI)

Aaron Berscheid, CPW District Wildlife Manager

Exhibit BSouth Republican River Fish Kill Investigation - Witness Statement

Aaron Berscheid, CPW District Wildlife Manager

Exhibit CSouth Republican River Fish Kill Investigation - Fish Counting Records

FISH-COUNTING RECORD

AREA SAMPLED: Shoreline ___X__ Stream_______ Transect_______ Length or Area_______

Water Code: 80524___ Date__06/08/2015_______

LOCATION: _East Shore Hale Pond_1_____________COUNTY: __Yuma_______

INVESTIGATORS: Aaron Berscheid

TIME: Start_6:00 PM____ Finish_6:20 PM___ NOTES: UTM: 13S, x(E): 752472, y(N): 4392609.

One person searched east and west shore (see next record sheet) of Hale Pond 1 for a total of

20 minutes. Total search time for both east and west shores was 20 minutes. Water Quality

measurements for this site were collected on 06.09.15 at approximately 6:55 PM: pH: 8, DO: 5,

Water Temp: 28C. Fish lengths were not measured.

INCH-CLASS

SPECIE

S1 2 3 4 5 6 7 8 9

1

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Channe

l

Catfish

(CCF)

Total- 1

Bluegill

Sunfish

(BGL)

Total-

14

Golden

Shiner

(GSH)

Total- 2

Total

Fish

Found-

17



Water Code: 80524___ Date__06/08/2015_______

LOCATION: _West Shore Hale Pond 1___________COUNTY: __Yuma_______ INVESTIGATORS:

Aaron Berscheid


One person searched east (see previous record sheet) and west shore of Hale Pond 1 for a total

of 20 minutes. Total search time for both east and west shores was 20 minutes. Water Quality

measurements for this site were collected on 06.09.15 at approximately 6:55 PM: pH: 8, DO: 5,

Water Temp: 28C. Fish lengths were not measured.

INCH-CLASS

SPECIE

S1 2 3 4 5 6 7 8 9

1

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Bluegill

Sunfish

(BGL)

Total-

20

Golden

Shiner

(GSH)

Total-

1

Green

Sunfish

(SNF)

Total-

2

Total

Fish

Found-

23


AREA SAMPLED: Shoreline______ Stream___X____ Transect_______ Length or Area__300

ft_____ WaterCode: 33153____ Date_6/9/2015____

LOCATION: __RRSpil1_________________COUNTY:___Yuma_______ INVESTIGATORS: Aaron

Berscheid, Paul Foutz__

TIME: Start ___12:55 PM__Finish_1:55 PM_____ NOTES: *Mutilated- Fish was identifiable but

incomplete. Decomposed was unidentifiable and unmeasurable, but counted as a fish. Two

people searched for 30 minutes, then four people searched for another 30 minutes. Total

search time was 180 minutes. Note: Crayfish (CFI) found was 21. Start UTM: 13S, x(E):

0745394, y(N): 4391490; Approximate End UTM (from map): 13S, x(E): 745433, y(N): 4391473.

Water quality collected on site at time of search; pH: 8, DO: 9, Water Temp: 26.7 C

INCH-CLASS

SPECIES 1 2 3 4 5 6 7 8 91

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Plains

Killifish

(PKF)

5 3

Red Shiner

(RDS)

1 4

7

4

Stonecat

Catfish

(STP)

1 4 2

Black

Bullhead

Catfish

(BBH)

*Mutilated-

3

1 1

White

Sucker

(WHS)

*Mutilated-

1

1 1 2 2

Creek Chub

(CRC)

2 1 2 1

Largemout

h Bass

(LMB)

1

Orangethro

at Darter

(ORD)

1

Fathead

Minnow

(FMW)

3 2

4

Central

Stoneroller

1 5 7 2

(STR)

Brassy

Minnow

(BMW)

1 1

Sand

Shiner

(SAH)

4

Unidentifia

ble

Decompos

ed- 8

9 6 1

Total Fish

Found- 159






TIME: Start ___4:03 PM__Finish_4:58 PM_____ NOTES: Decomposed was unidentifiable and

unmeasurable, but counted as a fish. Two people searched for 40 minutes, then four people

search for 15 minutes. Total search time was 140 minutes. Note: Crayfish (CFI) found was 3.

Start UTM: 13S, x(E): 0747148, y(N): 4391460; End UTM: 13S, x(E): 747116, y(N): 4391532.

Water quality collected on site at time of search; pH: 8, DO: 9, Water Temp: 29.4 C

INCH-CLASS

SPECIES 1 2 3 4 5 6 7 8 91

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Plains

Killifish

(PKF)

2 2

Red Shiner

(RDS)

1

8

1

Stonecat

Catfish

(STP)

1 2 1 1

Black

Bullhead

Catfish

(BBH)

3 1

White

Sucker

(WHS)

2 2 4

Creek Chub

(CRC)

5 8 7 3

Western

Mosquitofi

sh (MSQ)

1

Orangethro

at Darter

(ORD)

1

Fathead

Minnow

(FMW)

1 1

7

1

Central 4 2

Stoneroller

(STR)

Brassy

Minnow

(BMW)

1

Sand

Shiner

(SAH)

5

Unidentifia

ble

Decompos

ed- 42

1 1

Total Fish

Found-

140







unmeasurable, but counted as a fish. Three people searched for 32 minutes. Total search time

was 96 minutes. Note: Crayfish (CFI) found was 15. Start UTM: 13S, x(E): 0752262, y(N):

4392782; End UTM: 13S, x(E): 752332, y(N): 4392803. Water quality collected on site at time of

search; pH: 8, DO: 4.77 (ODO meter), Water Temp: 27.8 C.

INCH-CLASS

SPECIES 1 2 3 4 5 6 7 8 91

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Grass Crap

(WHA)

1

Stonecat

Catfish

(STP)

1 1

Black

Bullhead

Catfish

(BBH)

1 1

White

Sucker

(WHS)

1 2 2

Creek Chub

(CRC)

3 2 1 2

Central

Stoneroller

(STR)

1 1 1

Sand Shiner

(SAH)

2

Unidentifia

ble

Decompose

d- 18

Total Fish

Found-

41



ft_____ WaterCode: 33153___ Date_6/9/2015____




unmeasurable, but counted as a fish. Two people searched for 7 minutes, three people

searched for 10 minutes, and 4 people searched for 15 minutes. Total search time was 104

minutes. Note: Crayfish (CFI) found was 31. Start UTM: 13S, x(E): 07452884, y(N): 4393764;

End UTM: 13S, x(E): 752962, y(N): 4393787. Water quality collected on site at time of search;

pH: 8, DO: 4, Water Temp: 26.7 C.

INCH-CLASS

SPECIES 1 2 3 4 5 6 7 8 91

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Common

Carp (CCP)

1

Stonecat

Catfish

(STP)

2

White

Sucker

(WHS)

1 1

Creek Chub

(CRC)

1 1 3

Fathead

Minnow

(FMW)

1

Central 6 2 2 1

Stoneroller

(STR)

Unidentifia

ble

Decompose

d- 11

2 4

Total Fish

Found- 39



WaterCode: 80524____ Date__06/10/2015_______

LOCATION: _ West half of Hale Pond 1______COUNTY: __Yuma_______ INVESTIGATORS: Aaron

Berscheid


One person searched west half of Hale Pond 1 from a float tube for a total of 45 minutes. Total

search time was 45 minutes. Fish lengths were not measured.

INCH-CLASS

SPECIES 1 2 3 4 5 6 7 8 91

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

White

Sucker

(WHS)

Total- 1

Freshwater

Drum

(DRM)

Total- 1

Black

Crappie

(BRA)

Total- 3

Sunfish (no

spp.

identificati

on)

Total- 14

Channel

Catfish

(CCF)

Total- 3

Golden

Shiner

(GSH) or

Gizzard

Shad (GSD)

Total- 6

Total Fish

Found- 28


AREA SAMPLED: Shoreline______ Stream ___X____ Transect_______ Length or Area__300

ft_____ WaterCode: 33153___ Date_6/11/2015____

LOCATION: __ RRSpil5- Control Site_________________COUNTY:___Yuma_______

INVESTIGATORS: Aaron Berscheid__

TIME: Start ___4:12 PM__Finish_5:12 PM_____ NOTES: Start UTM: 13S, x(E): 0744410, y(N):

4391202, End UTM: 13S, x(E):744405, y(N): 4391276. One person searched for 60 minutes.

Total search time was 60 minutes. No dead fish were detected on this transect. No water

quality collected on site at time of search.

INCH-CLASS

SPECIE

S1 2 3 4 5 6 7 8 9

1

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Total

Fish

Found-

0



WaterCode: 80524_ Date__06/11/2015_______

LOCATION: _Hale Pond 1_________________COUNTY: __Yuma_______ INVESTIGATORS:

Aaron Berscheid, Dave Nicklos_______


One person searched Hale Pond 1 from a float tube for a total of 1 hour and 45 minutes. Total

search time was 105 minutes. Fish lengths were not measured.

INCH-CLASS

SPECIES 1 2 3 4 5 6 7 8 91

0

1

1

1

2

1

3

1

4

1

5

1

6

1

7

1

8

1

9

2

0

2

1

Channel

Catfish

(CCF)

Total- 61

Trout (TRT)

Total- 27

Black

Bullhead

(BBH)

Total- 10

Common

Carp (CCP)

Total- 63

Sunfish (no

spp.

identificati

on)

Total- 620

Crappie

(CRA)

Total- 21

Largemout

h Bass

(LMB)

Total- 43

White

Sucker

(WHS)

Total- 5

Golden

Shiner

(GSH) or

Gizzard

Shad (GSD)

Total- 469

Unknown

(UNK)

Total- 2

Total Fish

Found-

1321

Exhibit DSouth Republican River Fish Kill – CDPHE Compliance Letter

Exhibit ESouth Republican River Fish Kill – Water Quality Analysis by Melynda May

Colorado Parks and Wildlife Water Quality Coordinator

Water quality measurements and samples were collected by CPW and CDPHE on 6/9/2015 following a spill of animal waste to the South Republican River on 6/5/2015. CPW measurements were taken with a Hach Kit unless otherwise noted in Table 1. CDPHE samples were collected and analyzed at the CDPHE Laboratory Services Division (Table 2). Locations 1 and 2 sampled by CDPHE were collected in the unnamed tributary that the animal waste travelled down to reach the South Fork of the Republican River. These samples are most representative of the discharged wastewater. Locations 3 and 4 are in the vicinity of the fish kill investigation.

These samples and measurements were taken approximately four days after the spill occurred, because the spill was not reported. Much of the spilled effluent would have been washed downstream by the time the site was investigated. Therefore, the water quality conditions measured and sampled on the date of the investigation are much better than the conditions experienced by the biological aquatic community immediately after the spill occurred. The water-quality measurements and results collected on the day of CPW’s and CDPHE’s investigation are summarized in Tables 1 and 2. The applicable numeric standards at the sites where the fish kill was investigated are summarized in Tables 3 and 4.

Table 1. CPW water quality sampling locations and resultsSample Location Sample date/time Dissolved Oxygen

(mg/L)Temperature

oCpH

East Shore Hale Pond 1

6/9/2015 6:55 pm 5 28 8

West Shore Hale Pond 6/9/2015 6:55 pm 5 28 8RRSpil1 6/9/2015 12:55 pm – 1:55

pm9 26.7 8

RRSpil2 6/9/2015 4:03 pm – 4:48 pm 9 29.4 8RRSpil3 6/9/2015 6:30 pm – 7:02 pm 4.77 (ODO meter) 27.8 8RRSpil4 6/9/2015 8:01 pm – 8:33 pm 4 26.7 8

Table 2. CDPHE water quality sampling locations and resultsSample Location Sample

date/timeBiochemical

Oxygen Demand (mg/L)

Ammonia (mg/L)

Nitrate (mg/L)

Total Nitrogen (mg/L)

Total phosphorus

(mg/L)

total dissolved

solids (mg/L)

total suspended

solids (mg/L)

Location 1 – unnamed drainage pool below culvert under Yuma County Road 7

6/9/2015 84 14 <0.05 23 11 680 880

Location 2 – unnamed drainage 2.4 miles below Yuma County Road 7

6/9/2015 >1800 290 2.3 330 50 4800 420

Location 3 - South Fork Republican River below unnamed drainage

6/9/2015 12 0.092 <0.05 0.97 0.39 460 <10

Location 4 – Hale pond

6/9/2015 21 0.0029 <0.05 1.7 0.53 440 16

Table 3. Hale Pond: applicable standards from Regulation 38, Republican River segment 8Parameter chronic acuteDissolved oxygen (mg/L)

5.0

Ammonia (mg/L) 1.02 8.4Nitrate (mg/L) 10

Table 4. South Fork Republican River: applicable standards from Regulation 38, Republican River segment 1Parameter chronic acuteDissolved oxygen (mg/L)

5.0

Ammonia (mg/L) 0.93 8.4Nitrate (mg/L) 10

Dissolved oxygenOn 6/9/2015, the dissolved oxygen measured in Hale Pond was 5 mg/L, which is equal to the standard of 5.0 mg/L. The dissolved oxygen in the South Fork Republican River ranged from 4 mg/L to 9 mg/L. Two locations, RRSpil3 and RRSpil4, were below the dissolved oxygen minimum value of 5.0 mg/L.

Dissolved oxygen values were likely worse (lower) immediately after the spill occurred, and in the days prior to the investigation conducted by CPW. Biochemical Oxygen Demand (BOD) is a measure of contamination that consumes dissolved oxygen. BOD is usually less than 1 mg/L in pristine rivers, and between 2 and 8 mg/L in moderately polluted rivers. Sewage treatment plants are not allowed to discharge BOD higher than 30 mg/L.

Based on the high BOD levels measured closes to the spilled effluent, and low dissolved oxygen measured in Hale Pond (which will flush less quickly than the river), it is likely that low dissolved oxygen contributed to the observed fish kill in the South Republican River and Hale Pond.

AmmoniaOn 6/9/2015, the ammonia in Hale Pond was 0.0029 mg/L, which is less than the applicable chronic standard of 1.02 mg/L, and the applicable acute standard of 8.4 mg/L. The ammonia in the South Fork of the Republican River was 0.092 mg/L, which is also less than the applicable chronic standard of 0.93 mg/L

The two locations closest to the spill discharge had very high ammonia concentrations of 14 mg/L and 290 mg/L at the time of CPW’s investigation indicating that the spilled effluent likely had very high ammonia concentrations. High ammonia concentrations are consistent with animal waste. Therefore, ammonia concentrations where likely much higher in the South Republican River and Hale Pond immediately after the spill occurred, and in the days prior to the investigation conducted by CPW.

The applicable ammonia standard varies depending on temperature and pH, but acute values range from 1.3 mg/L to 48.8 mg/L, across the allowable range of pH (6.5-9.0). Based on the high ammonia levels measured closed to the spilled effluent measured four-days after the spill, it is likely that ammonia contributed to the observed fish kill in the South Republican River and Hale Pond.

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