Fish Passage Site 20501464

Coordinates (dec. deg.): 61.98914°, -149.96030°
Legal Description: S022N004W23
Region: South Central
Road Name: Hidden Hills Road

Datum: WGS84
Quad Name / ITM: Anchorage D-8
AWC Stream #: 247-41-10200-2190-3020
Stream Name: Caswell Creek tributary


Site Comments: Creek is the outlet stream to the smaller Caswell Lakes complex.

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.


Project Supervisor: Gillian O'Doherty, ADFG
Observers: Mark Eisenman, Shane Hetzog

Overall Fish Passage Rating: Green

Tidal: No
Backwatered: No

Step Pools: No
Construction Year: 2012

Site Observations:

  1. None of this type

Comments: Replaced with a stream simulation culvert in June 2012. Culvert reassessment Sept. 2018. 12 adult spawning Coho observed downstream of culvert, 2 adult Coho observed inside culvert, and 3 adult Coho upstream of crossing. Upstream channel has been reconstructed for over 300 feet. Upstream and downstream bioengineering well established with willow and alders up to 12 feet or higher. Upstream constructed channel about 8 feet wide.

Culvert Measurements

ID: 1 Structure Type: Pipe-arch (Structural steel plate) Fish Passage Rating: Green
Length(ft): 100.3
Inlet Type: Projecting
Outlet Type: Projecting
Corrugation Depth(in.): 2.0
Corrugation Width(in.): 6.25
Condition Rating(1-5): 4
Approach Angle: 0.0
Sedimentation At Inlet: No
Inlet Substrate: Cobble
Outlet Substrate: Cobble
Width(ft):12.9 13.3
Height(ft):8.04 8.52
Apron Length(ft):
Water Depth(ft): 1.12
Rustline Height(ft):
Substrate Depth(ft):1.3 0.8
Backwatered?: No
Baffles Present: No
Embedded?: Yes
Embedded Depth(ft): 0.8
Outfall Height: 0.0
Outfall Type: At Stream Grade
Constriction Ratio:
Culvert Gradient: 0.97%
Max Slope:
Max Slope Length:

Comments: Construction plans list the culvert dimensions as a 13.25 x 9.3 PA, SSP. Substrate depths estimated from taking the difference of the opening and the listed culvert height.

  Culvert Observations:
  1. None of this type

Stream Measurements

Stream SubstratesUpstreamDownstream
Stream Slope(deg.):1.28
Stream Flow Stage:Medium

No stream width data available.


Locator ID Culvert
Distance (ft)1
Distance From
Crossing (ft)2
Elevation (ft)
D/S Grade Ctrl (Thalweg) 0.00 90.74
D/S Water Surface Elev 0.00 91.38
D/S Thalweg (Max pool depth) 30.00 89.98
D/S Water Surface Elev 30.00 91.68
D/S Tailcrest or 1st Thalweg 84.00 91.68
D/S Water Surface Elev 84.00 92.33
D/S Thalweg (Outlet riffle mid point) 99.00 91.15
D/S Water Surface Elev 99.00 92.44
Outlet Invert (On substrate) 125.00 91.43
D/S Water Surface Elev 125.00 92.55
Outlet Culvert Top 125.00 100.00
Inlet Culvert Top 225.30 100.97
Inlet Culvert Invert (On substrate) 225.30 92.75
U/S Water Surface Elev 225.30 93.79
U/S Thalweg (Profile point in upstream riffle) 250.30 93.11
U/S Water Surface Elev 250.30 93.83
U/S Thalweg (Profile point in upstream riffle) 275.30 93.18
U/S Water Surface Elev 275.30 93.98
U/S Thalweg (Profile point in upstream riffle) 300.30 93.75
U/S Water Surface Elev 300.30 94.64
U/S Thalweg (Profile point in upstream riffle) 325.30 94.22
U/S Water Surface Elev 325.50 94.79


  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: Visual Observation, Ground (A)
Comments: 9/26/18 - 12 Adult spawning coho observed DS of culvert, 2 inside culvert, and 3 upstream of culvert

Fish Observations

Species: adult spawning coho salmon Life History: Anadromous
Total Fish Observed: 17 Fish Measured: Fork Lengths (mm) Min: Max: Mean:
Collected/Observed by Gear Type: At Site Visual Observation, Ground (17)  

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