Lewis Creek Reach M19Lewis Creek Reach M19

Phase 1, Phase 2, and Phase 3Phase 1, Phase 2, and Phase 3

Lewis Creek Watershed

M19

Phases of Assessment• Phase 1 - Remote Sensing and Existing Data

• Phase 2 - Qualitative and Rapid Field Assessment

• Phase 3 - Field Survey Assessment

Watershed Reach

and Segment-Level Approaches

Topographic lines overlaid on Orthos

Local Knowledge and NRCS Information1) Channelization upstream of farm

bridge occurred in 60’s2) Rip-rap routinely installed since at

least early 80’s3) Current farm bridge moved to new

location in 19814) Past landowners did channel

“work” to maintain straighter channel

5) High floods in the late 1980’s6) Out of bank flows occur about every

2 years, flashy events every year7) Entire valley bottom has been

flooded in past8) Soil cores done on Lewis Creek

Farm confirm presence of glacial lake clays in valley bottom

9) Bank re-vegetation projects occurred in 1990’s on Lewis Creek Farm

1905

1983

Topographic Map Comparison

1942 1995

Orthophoto Comparison

Changes in Planform

1983 Topographic Map

(Corridor is approx 475 ft wide at ball field area and approx 375 ft wide along the remainder of the reach)

Phase 1 River Corridor

Parameters evaluated in Phase 1 Corridor

1) Soils and Geology

2) Land Use and Land Cover

3) Riparian Vegetation

4) Berms, Roads & Improved Paths

5) Development

Soils Data and approximate

Valley Wall Lines Corridor where soils reviewed

Approximate valley wall

Parent Material

Flood Potential

Slope Types

Various types of soil parameters that can be evaluated using the soil maps.

Reach Number

Stream Type

Total impact

(out of 32)

Step 4 Land Use

Impact (out of 6)

Step 5 Instream

Modification Impact (out of 10)

Step 6 Floodplain

Modification Impact (out of 12)

Step 7 Windshield

Survey Impact

(out of 4)

Watershed Size

Confinement

M19 C 14 3 4 5 2 18.21 3-VB

Types of Impacts seen along stream reach:

1) Active Agriculture in corridor (crop) {Step 4}2) Little to no Riparian vegetation {Step 4}3) Channel modification (straightening) {Step 5}4) Bank Armoring (Rock rip-rap) {Step 5}5) Mid-channel bars {Step 6}6) Planform changes (meander migration & avulsions) {Step 6}7) Erosion {Step 7}

Phase 2, Rapid Field Assessment

Field verification of Phase 1 data

Collecting data using the Field Form, Rapid Habitat & Geomorphic Assessments

Identifying condition and stream type of the reach

Geomorphic and Habitat AssessmentAssessment Objectives

• Identification of:

– stream condition as compared to a reference stream of the same type

– adjustment process or physical change currently underway in the channel

– sensitivity of valley, floodplain, and channel to human or natural changes

Examples of field parameters evaluated• Valley & Floodplain Corridor Land Use/Land Cover• Soils and Geology• Riparian Vegetation• Bankfull Height and Flood-prone Width• Habitat Conditions

Evaluating:•Bank Vegetation•Riparian Vegetation•Corridor Land Use

Measuring channel data:•Width•Depth•Flood Prone Width•Entrenchment

Enjoying the point bar for a break and review of

parameters. *Sediment size on point bar*Sediment size in different bed features

Measuring the distance

between riffles

Noting:•Bank Erosion and Scour•Bank Slope

Recording Types of Bank Protection:•Rip-rap•Tree revetments

Sediment types seen along reach:1) Gravels2) Sands3) Clays and silts

Comparison of upper and lower bank material

Fines

Small gravels

Evaluating types of bed sediment storage seen:•Mid-channel bars•Point bars•Diagonal Bars

BD

BD

Beaver Activity

May Affect Stream by:

1) Changing water levels2) Altering Sediment deposition locations3) Influencing planform changes4) Creating or changing habitat features

Reach Number Segment

Bankfull Width

(ft)

Flood-prone Width

(ft)

Max Depth

(ft)

Low Bank

Height (ft)

Entrench-ment

Width/Depth Ratio Sinuosity

Channel Slope

(Phase1)Incision

Ratio

Stream Type

Stream Type Bed

Material

Stream Bed

Feature Type

M19 A 40 500 3 - 4.5 18.7 Moderate 0.40% - C 4Riffle-Pool

*M19 B 69 500 4 - 7.2 24.4 Moderate 0.40% - C 4Riffle-Pool

Reach Number Segment

Habitat Condition

Geomorphic Condition

Dominant Adjustment

Process

Concurrent Adjustment

ProcessStage of Channel

Evolution

* Channel Sensitivity to Disturbance

M19 A Poor Poor Widening Aggredation Widening –III /IVvery high to

extreme

*M19 B Fair Fair Aggredation Widening Widening –III /IVvery high to

extreme

Some of the things that affected the habitat were:1)Sediment deposition, embedded riffles

2) Lack of riffles and fast deep water,

3) Low diversity of substrate for epifaunal colonization

4) Bank stability / erosion, and

5) Poor riparian buffer protection.

* There are good pools in the reach, and many small black-nose dace and creek-chubs were seen. * The upstream half does have good shading from a treed buffer of 25ft to 50ft wide; the

downstream buffer mainly herbaceous with a few shrubs and trees mixed in, so little shade is

provided to the stream in this section.

Some things that affected the geomorphic condition were:1) Small amount of channel incision

2) Sedimentation

3) Bank failure and scour – over widened channel in locations

4) Changes in planform; avulsions, channel bars, and thalweg not always lined up with planform

Phase 3 , Survey Level Assessment

• Further verify the stream type.

• Establish cross-sections for long term monitoring

• Evaluate sediment size being transported by stream

Lewis Creek at North Ferrisburg, VT

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1990 1992 1994 1996 1998 2000

Annual Peaks 10 yr Discharge 25 yr Discharge 50 yr Discharge

1990 1991 1994 1996 1998 2000

1912191419161917192019221927193019321934193619381940194219441946194819501952195419561958195919621964196619681970197219731976197719801982198419861988199019921994199619982000

Flood History

Otter Creek at Middlebury, VT

0

2000

4000

6000

8000

10000

12000

14000

16000

1904190619121914191619181927193019321934193619381940194219441946194819501952195419561958196019621964196619681970197219741976197819801982198419861987199019921994199619982000

Annual Peaks 10 yr Discharge 25 yr Discharge 50 yr Discharge

1990 1993 1995 1996 1999 2000

1990 1992 1994 1996 1998 2000

From Gage Records

Bankfull stage flows in spring of 2002

Bankfull stage flows in spring of 2002

Lewis Creek

-100

-50

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700-1100-1050-1000-950-900-850-800-750-700-650-600-550-500-450-400-350-300-250-200-150-100-50 0

East West Distance (ft)

North South Distance (ft)

XS 4

XS 5

XS 3

XS 2

XS 1

Channel Planform and

Cross-section Location

5 Monumented Cross-sections

established

Measuring Bankfull and Flood-prone Width

Flood-prone elevation

Bankfull elevation

Lewis Creek 1

10

12

14

16

18

20

22

0 20 40 60 80 100 120 140 160

Distance From Lef t Bank (f t)

Elevation (ft)

XS –1RiffleWidth = 33 ftMax Depth = 3.45 ftFPW = ~150 ftD50 = 10.66 mm (medium gravel)Stream Type = C4

Lewis Creek 2

10

12

14

16

18

20

22

0 10 20 30 40 50 60 70 80

Distance From Lef t Bank (f t)

Elevation (ft)

XS –2RunWidth = 31.74 ftMax Depth = 4.03 ftFPW = ~200 ftD50 = 1.34 mm (very coarse sand)Stream Type = E5

Lewis Creek 3

10

12

14

16

18

20

22

0 10 20 30 40 50 60 70

Distance From Left Bank (ft)

Elevation (ft)

XS – 3RunWidth = 27.49 ftMax Depth = 3.49 ftFPW = ~300 ftD50 = 0.57 mm (coarse sand)Stream Type = E5

Lewis Creek 4

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35 40 45

Distance From Lef t Bank (f t)

Elevation (ft)

XS – 4RunWidth = 38 ftMax Depth = 3.6 ftFPW = ~300 ftD50 = 0.25 mm (medium sand)Stream Type = C5

Lewis Creek 5

6

8

10

12

14

16

0 10 20 30 40 50 60 70 80 90

Distance From Lef t Bank (f t)

Elevation (ft)

XS – 5RiffleWidth = 26.28 ftMax Depth = 4.25 ftFPW = ~300 ftD50 = 7.10 mm (fine gravel)Stream Type = E4

Valley slope = 0.46%(change in elevation of water surface /down valley length)(13.3 – 7.91 / 1170)

Channel Slope = 0.23%(change in elevation of water surface / channel length)(13.3 – 7.91 / 2348)

Lew is Creek

4

6

8

10

12

14

16

18

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

Channel Distance (ft)

Elevation (ft)

thalweg water srf LB RB BKF XS

Channel Longitudinal Profile

Beaver damBeaver dam

Size percent less than (mm) Percent by substrate type

D16 D35 D50 D84 D95 silt/clay sand gravel cobble boulder bedrock

Particle Size (mm) Total 0.077 0.301 1.391 26.781 53.748 11% 41% 45% 3% 0% 0%Percent Finer Than Riffle 0.124 0.871 8.436 35.315 58.720 6% 31% 59% 4% 0% 0%

Pool

Run 0.067 0.138 0.750 17.492 50.776 14% 47% 37% 2% 0% 0%

Glide

Total Pebble Count

0%10%

20%

30%

40%50%

60%

70%80%

90%

100%

0.01 0.1 1 10 100 1000 10000

Particle Size (mm)

Percent Finer Than

Runs

Total

Riffles

Example of Prioritizing Reaches(in order of highest to lowest priority)

• Conservation Reaches- Least disturbed, river structure and vegetation intact

• Strategic Sites- Highly sensitive to disturbance, impacts may trigger off site response

• Reaches with High Recovery Potential- Possible self adjustment or minimal management efforts

• Moderate to Highly Degraded Sites- Require invasive management strategy

How the some of the Data from the Assessments has been used to date:

1) Assisting LCA with making recommendation to Town of Starksboro for their management plan of the Cota Farm property

2) Insuring that recreation path and potential structures are out of the flood plain and potential changes in the channels planform

3) Establishing cross-sections for long term monitoring. Ability to determine rate of change laterally and vertically along reach.

4) Providing the USFW with information on where habitat features and riparian planting may be needed

* Reach is a good candidate for a Passive Geomorphic Approach

Involves the removal of constraints from a river corridor thereby allowing the river, utilizing its own energy and watershed inputs to re-establish its meanders, floodplains, and self maintaining, sustainable equilibrium condition over an extended time period.

Active riparian buffer re-vegetation and long-term protection of a river corridor is essential to this alternative.