Fish Passage Site 20601536

Coordinates (dec. deg.): 61.12846°, -151.22820°
Legal Description: S012N011W16
Region: South Central
Road Name: Pan Am Road

Datum: NAD83
Quad Name / ITM: Tyonek A-4
AWC Stream #:
Stream Name: Unnamed Tributary to Chuitna


Site Comments: None

Multiple surveys have been conducted at this site — click on the drop down
arrow to the right of the survey date below to choose a different report for this site.

Survey UPDATE-1536

Project Supervisor: Gillian O'Doherty, ADFG
Observers: Mark Eisenman, Robert Pype

Overall Fish Passage Rating: Gray

Tidal: No
Backwatered: Yes

Step Pools: No
Construction Year:

Site Observations:

  1. Constriction ratio gray

Comments: Nice habitat upstream stream widens out and has a gravel substrate. Downstream also has gravel substrate, most likely from road washouts. Nice pool/riffle complexes. Lots of dead fall over creek directly upstream from inlet and might cause a debris jam at higher flows. Culvert looks to have been recently replaced, but still undersized for creek. The generations of blown out culverts have been piled up next the road. Culvert is technically backwatered with the tail water control being higher than inlet invert and water surfaces very close to same elevation. However this new culvert is not any larger than the previously failed culverts and the issue of constriction and debris has not been addressed. Downstream control likely to fail in the next highwater event and this culvert is likely to fail again.

Culvert Measurements

ID: 1 Structure Type: Circular pipe (Corrugated steel) Fish Passage Rating: Gray
Length(ft): 32.1
Inlet Type: Projecting
Outlet Type: Projecting
Corrugation Depth(in.): 0.5
Corrugation Width(in.): 2.5
Condition Rating(1-5): 5
Approach Angle: 0.0
Sedimentation At Inlet: No
Inlet Substrate: None
Outlet Substrate: None
Width(ft):4.0 4.0
Height(ft):4.0 3.11
Apron Length(ft):
Water Depth(ft): 0.9
Rustline Height(ft):
Substrate Depth(ft):
Backwatered?: Yes
Baffles Present: No
Embedded?: No
Outfall Height: 0.0
Outfall Type: At Stream Grade
Constriction Ratio: 0.61
Culvert Gradient: -0.00%
Max Slope:
Max Slope Length:
  Culvert Observations:
  1. Constriction ratio gray

Stream Measurements

Stream SubstratesUpstreamDownstream
Stream Slope(deg.):
Stream Flow Stage:Medium
Stream Width Type Distance From
Crossing (ft)
Width (ft)
Upstream ordinary high water 50.0 6.40
Upstream ordinary high water 100.0 7.60
Upstream ordinary high water 125.0 5.00
Upstream ordinary high water 200.0 7.00


Locator ID Culvert
Distance (ft)1
Distance From
Crossing (ft)2
Elevation (ft)
Road Elev 101.06
D/S Grade Ctrl (Thalweg) 0.00 92.26
D/S Water Surface Elev 0.00 96.46
D/S Tailcrest or 1st Thalweg 33.00 96.49
D/S Water Surface Elev 33.00 96.91
Max Pool Depth 54.00 95.60
Outlet Pool Water Elev 54.00 96.92
Outlet Invert (On pipe) 69.00 96.02
D/S Water Surface Elev 69.00 96.92
Outlet Culvert Top 69.00 99.99
Inlet Culvert Top 101.10 100.03
Inlet Culvert Invert (On pipe, 1st resting) 101.10 96.00
U/S Water Surface Elev 101.10 96.94
U/S Thalweg 110.10 96.12
U/S Water Surface Elev 110.10 96.92


  1. River distance is measured continuously throughout the survey reach along the thalweg of the stream.
  2. Measured from each end of the crossing along the thalweg of the stream.

Fish Sampling Efforts

Gear Type: Minnow Trap (A) Trap Duration(h): 18.0
Comments: Three traps set downstream at 20, 40 and 100 feet from outlet.
Gear Type: Minnow Trap (B) Trap Duration(h): 18.0
Comments: Trap set about 40 feet upstream from culvert.

Fish Observations

Species: juvenile coho salmon Life History: Anadromous
Total Fish Observed: 2 Fish Measured: 2 Fork Lengths (mm) Min: 72 Max: 75 Mean: 73
Collected/Observed by Gear Type: Downstream Minnow Trap (2)  

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