Mill Creek Fish Passage - Park to Roosevelt

Salmonid Habitat Restoration and Acquisition

Fish Passage Improvement
Project ID19-1718 R
Recovery DomainsMiddle Columbia River
Start Date12/12/2019
End Date11/17/2022
Last Edited05/03/2024
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This project completed fish passage improvements to 2,283 feet of the two-mile-long Mill Creek flood control channel. Modifications of the concrete channel provided depth and velocity conditions favorable to passage of summer steelhead, bull trout, and spring Chinook. Under pre-project conditions, returning adults encountered velocities that were too high for too long of a distance, without any resting opportunities. To improve passage, part of the existing channel was cut and removed. Pre-cast roughness panels replaced the removed concrete. The roughness panels have block-shaped projections which create friction in the water, slowing it to a velocity that the fish can swim for the full distance of the project. Resting pools were also added as an additional measure. During low flow, under pre-project conditions, baffles in the channel created hydraulic conditions that were a barrier to juveniles. The baffles were removed and replaced with new baffles that were sized and spaced to provide volitional passage for juveniles.

This project was originally scoped to improve 5,000 feet of fish passage in the concrete flume portion of Mill Creek that flows through Walla Walla, WA. Due to inflation, the costs of labor and materials for this work increased after the sponsor was awarded funding. The sponsor used all the resources available to stretch funds as far as possible and were only able to correct 4,081 feet of the concrete channel before funding ran out. Due to overlapping project areas the final reported passage in this project is .38 miles (project footprint from Otis to Division streets). The sponsor has leveraged funding across different RCO programs and has reported .39 miles of overlapping project areas in other funded project scopes.

Project Benefit    

The purpose is to provide adult and juvenile passage for summer steelhead, spring chinook, and bull trout through a segment of the Mill Creek flood control channel. The goals were to reduce high flow velocity, provide resting pools, and provide volitional passage for juveniles.


Metric Completed Originally
Fish Passage
  Barriers Removed
  Miles Opened .38 .97

Funding Details

Report Total:$3,250,000

Project Map


1-Mill Creek channel - Park S    

  • Worksite Identifier: 1-Mill Creek channel - Park S
  • Start Date:
  • End Date:
Area Description

No Area Description data was found for this worksite.

Location Information

  • Basin:
  • Subbasin:
  • Watershed:
  • Subwatershed:
  • State: Washington
  • Recovery Domain: Middle Columbia River
  • Latitude: 46.06919091
  • Longitude: -118.31265993


  • Middle Columbia River Steelhead DPS
  • Mid-Columbia River Spring-run Chinook Salmon ESU




  • C.0 Salmonid Habitat Restoration and AcquisitionY (Y/N)
    •      . . C.0.a Habitat restoration and acquisition funding 3,249,999.55
    •      . . C.0.b Length of stream treated/protected .38
    •      . . C.0.c
      Project identified in a Plan or Watershed Assessment
    •      . . C.0.d.1 Project Monitoring (LOV)
    •      . . C.0.d.2 Monitoring Location (LOV)
    •      . . C.2 Fish Passage ImprovementY (Y/N)
      •      . . . . C.2.a Fish Passage Funding 3,249,999.55
      •      . . . . C.2.b.1 Length of stream made accessible .38
      •      . . . . C.2.b.3 Type of blockage/barrier (LOV)
      •      . . . . C.2.b.4 Number of blockages/impediments/barriers impeding passage 1
      •      . . . . C.2.d.1 Fishway chutes or pools installedY (Y/N)
        •      . . . . . . C.2.d.2 Number of fishway chutes/pools installed 106