In-Stream Habitat Survey. Modified from ODFW entory/methods.html Quantitative method for assessing...

In-Stream Habitat Survey

In-Stream Habitat Survey

Modified from ODFW http://oregonstate.edu/Dept/ODFW/freshwater/

inventory/methods.html Quantitative method for assessing habitat for

fish 2 steps to survey:

Data collection Summary

Measurements are made at the “unit type” level

Habitat Units~~~~~~

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1

2

3

Unit Number

Unit Type

1 R

2 P

3 G

Unit Number Sequential # starting

downstream

Unit Type Riffle, glide, or pool

Unit Types – Riffle

RI Riffle: Fast, turbulent, shallow flow over gravel or cobble substrate.

Unit Types – Riffle

Unit Types – Glide

GL Glide: Fairly uniform depth and flow with no surface turbulence.

Deeper than riffle, but not deep enough to be a pool.

Unit Types – Glide

Unit Types – Pool

Unit Measurements

Length Width and Depth

Wetted Surface Active Channel

Depth at Pool Tail Crest (pools only) Channel Shade (left and right side) Percent Actively Eroding Bank Percent Undercut Bank

Pool Tail Crest

Place where water leaks out of pool (measure at deepest spot)

Measure for POOL units only

Max Depth

PTC Depth

FLOW

Shade

Measure using clinometer

90°80°

Substrate

Percent (within each unit) Silt/Organics Sand Gravel Cobble Boulder Bedrock

Large Boulder Count (>1.5 ft diameter)

Substrate Fine Sediments Coarse sediments Solid

Clay Silt Sand Gravel Cobble Boulder Bedrock

0.002 mm 0.05 mm 2 mm 6 cm 25 cm (0.25 in.) (2.5 in.) (10 in.) pea tennis ball bowling ball

1 2

3

Determining intermediate axis: 1 = Longest Axis (Length) 2 = Intermediate Axis (Width) 3 = Shortest Axis (Thickness)

Large Boulders

Large boulders create “pocket water”

Large Woody Debris

Large Woody Debris

LWD Type Diameter Length

Root Wad >6” -

Small >6” >10’

Medium >12” >20’

Large >20” >35’

Must be DEAD

Overhanging or in channel

Diameter = Circumference (approx. 3.14)

Diameter

Circumference

Habitat Summary

Why did we take all those measurements?

The Summary allows us to see whether our stream has desirable habitat for fish

Percent Pool Area

Percent Pool Area = Pool Area/Reach Area Pool Area = Length x Width for pool units Reach Area = Length x Width for ALL units

Pool PoolRiffle

Percent of stream area which is pool

Percent Pool Area

Pool Area = (10 x 10) + (10 x 10) = 200 Reach Area = (5 x 20) + 200 = 300 Percent Pool Area = 200/300 = 67%

Pool

W = 10’ L = 10’

Riffle

W = 5’, L = 20’

Pool

W = 10’ L = 10’

Percent Pool Area

Percent Pool Area = 200/300 = 67%

Habitat Benchmarks

Undesirable Between Desirable

Pool Area (%)

< 10 10-35 > 35

67% > 35%, so Pool Area = Desirable

Pool Frequency

Pool Frequency = Distance Between Pools / Channel Width Channel Width = Average width for all units

between pools

Pool PoolRiffle

Length/Width = distance btwn pools relative to stream width

Pool Frequency

Pool Frequency = Distance Between Pools / Channel Width

Pool Frequency = 20 / 5 = 4

Pool PoolRiffle

W = 5’, L = 20’

Pool Frequency

Pool Frequency = 20 / 5 = 4

Habitat Benchmarks

Undesirable Between Desirable

Pool Frequency

> 20 9 - 20 < 8

4 < 8, so Pool Frequency = Desirable

Residual Pool Depth

Residual Pool Depth = Max Depth – Pool Tail Crest Depth Important for low to no flow conditions

Max Depth

PTC Depth

Residual Pool Depth

Residual Pool Depth = Max Depth – Pool Tail Crest Depth

Example: Pool Depth = 3’ Pool Tail Crest = 1’ Residual Pool Depth = 2’

Residual Pool Depth

Habitat Benchmarks

Undesirable Between Desirable

Small Streams (<23 feet wide)

< 0.5 0.5 – 1.5 > 1.5

2’ > 1.5’ , so Residual Pool Depth = Desirable

Residual Pool Depth = 2’

Habitat Summary – Riffles

Width to Depth RatioPercent GravelPercent Sand-Silt-Organics

Riffle – Width to Depth

Width / Depth = 5 / 0.5 = 10

Pool PoolRiffle

W = 5’, D = 0.5’

Habitat Benchmarks

Undesirable Between Desirable

Width to Depth

> 30 15 - 30 < 15

Riffle – % Gravel

If % Gravel = 25%, Rating is Between

Habitat Benchmarks

Undes Btwn Desir

Percent Gravel

< 15 15 - 35 > 35

Riffle – % Sand-Silt-Organics

If % Sand-Silt-Organics = 10%, Rating is Between

Habitat Benchmarks

Undes Btwn Desir

Percent Sand-Silt-Organics

> 15 8 - 15 < 8

Values for streams with Volcanic Parent Material

Habitat Summary - LWD

Number of Pieces / 300’ Stream Reach Large LWD Pieces / 300’ Stream Reach

>20” Diameter and 35’ Length

Habitat Benchmarks

Undesirable Between Desirable

Number of Pieces < 10 10 – 20 > 20

Large Pieces < 1 1 – 3 > 3

Habitat Summary

90°80°

Shade (average for entire reach) Left + Right Bank Shade (degrees) / 180 Final Shade in %

90° + 80° = 170° 170 / 180 = 94%

Habitat BenchmarksSHADE (REACH AVERAGE %) U B D

Stream Width <40 feet

West Side <60 60 – 70 >70

Northeast <50 50 – 60 >60

Central-Southeast <40 40 – 50 >50

Stream Width >40 feet

West Side <50 50 – 60 >60

Northeast <40 40 – 50 >50

Central-Southeast <30 30 – 40 >40

94% > 70%