Nursery Bridge Reach Phase II Fish Passage and In-stream Habitat Enhancement IV

Salmonid Habitat Restoration and Acquisition

Fish Passage Improvement
Project ID22-Umat-04
Recovery DomainsMiddle Columbia River
Start Date05/01/2024
End Date12/31/2025
Last Edited04/18/2024
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The Nursery Bridge Reach of the Walla Walla River is one of two major fish passage bottlenecks in the Walla Walla subbasin that currently impact recovery of Middle Columbia River summer steelhead, Columbia River bull trout, and spring Chinook salmon. Over a century of impacts from urbanization, channelization, and agriculture has resulted in extreme constriction of the Walla Walla River, reducing its nearly 5-mile wide active alluvial fan to the current floodprone width of approximately 300 feet. The Nursery Bridge Reach is a highly altered portion of the Walla Walla River near Milton-Freewater, Oregon, that includes several road and railroad crossings, a significant point of diversion for senior water users, and an extensive flood risk management project consisting of a levee system and a large grade control structure with two associated fishways.

Currently, the energetic, leveed reach above the grade control structure (GCS) transports sediment through the Nursery Bridge reach where it locally deposits sediment in the vicinity of the GCS, largely due to the geometry of the river at this location and hydraulic shading from bridge piers in the channel. This localized sedimentation greatly reduces the efficacy of the fishways at the GCS and interrupts flow to the WWRID diversion. Both the fishways and the WWRID diversion require multiple in-channel manipulations per year to maintain water delivery to the diversion and flow continuity with the fishway.

The objective of this project is to provide stable fish passage connectivity to the Eastside Fishway at the GCS, reliable inflows to the WWRID diversion, and habitat for salmonids over a range of flows. Fish passage stability will be achieved through a combination of designed features. A shallow notch in the GCS and an approximately 350-foot roughened riffle low flow channel will be constructed to maintain mobility of bedload through the reach and a stable low-flow channel directly upstream of the GCS across the Eastside Fishway. Additionally, the WWRID Eastside diversion is proposed to be consolidated with the upstream Little Walla Walla River diversion and run through a new pressurized pipeline to serve the Eastside water users. The proposed channel alignment and designed structures will reduce the need for annual dredging and provide access to critical sections of the channel that would allow for maintenance without mobilizing equipment into the stream.

PCSRF funds for this project would specifically be spent on subcontract fees for barrier removal to enhance fish passage at the GCS. The CTUIR and project partners are proposing to enhance fish passage at the Nursery Bridge GCS by creating an 18-inch deep by 20-foot wide notch in the crest of the GCS near the entrance of the Eastside Fishway. The grade-controlled low flow channel is designed to maintain water surface elevations to reliably deliver water to the entrance to the Eastside Fishway with minimal annual maintenance and disturbance to the channel.

This project is a continuation of the work that occurred in the Nursery Reach Phase I (project 21-Umat-02). Proposed metrics have been divided between these two projects, with the fish ladder improvement ascribed to the 2021 project, and the removal of the barrier ascribed to this project.

Project Benefit    

Limiting factors for Middle Columbia River summer steelhead in the Nursery Bridge Reach include: blocked and impaired passage, degraded floodplain connectivity and function, degraded water temperature, altered sediment routing, and hydrologic alterations (NMFS 2009). Due to the infrastructure constraints in the reach, it may not be feasible to address all of the identified limiting factors; however, this project intends to address fish passage in the reach.

The proposed GCS notch and low flow channel in the immediate vicinity of the GCS will create a more stable channel adjacent to the entrance to the Eastside Fishway. Providing reliable fish passage at the Nursery Bridge GCS allows access to over 70 miles of some of the highest quality spawning and rearing habitat in the Walla Walla Subbasin, located within the North and South Forks of the Walla Walla River and Couse Creek. This project would increase the efficacy of the Eastside Fishway at the GCS and allow volitional passage for all life stages of ESA-listed salmonids to meet ODFW and NMFS fish passage requirements.

Due to the constrained nature of the flood control project in the Nursery Bridge reach, this project will likely not address the remaining limiting factors of floodplain connectivity, degraded water temperature, altered sediment routing, and hydrologic alteration. These factors will be addressed in future phases of the Nursery Bridge reach project.

Post-implementation action effectiveness monitoring is not specifically proposed for this project. The lack of project specific funding available for monitoring and the lack of applicability of this project within larger regional monitoring efforts due to its location within a confined flood control project makes the logistics of effectiveness monitoring of the project difficult. However, fish passage at the site is monitored by CTUIR Fish Passage Operations staff at the Nursery Bridge east and west fishways by virtue of monitoring ladder operations.


Metric Completed Originally
Fish Passage
  Barriers Removed 1
  Miles Opened 70.61

Funding Details

No Funding data has been entered for this project.

Project Map


Nursery Bridge Reach – RM 45.75 – 46.5    

  • Worksite Identifier: Nursery Bridge Reach – RM 45.75 – 46.5
  • Start Date: 05/01/0024
  • End Date: 12/31/0024
Area Description

No Area Description data was found for this worksite.

Location Information

  • Basin: Middle Columbia (170701)
  • Subbasin: Walla Walla (17070102)
  • Watershed: Middle Walla Walla River (1707010207)
  • Subwatershed: Garrison Creek-Walla Walla River (170701020704)
  • State: Oregon
  • Recovery Domain: Middle Columbia River
  • Latitude: 45.94517
  • Longitude: -118.384563


  • Middle Columbia River Steelhead DPS




  • C.0 Salmonid Habitat Restoration and AcquisitionY (Y/N)
    •      . . C.0.a Habitat restoration and acquisition funding .00
    •      . . C.0.b Length of stream treated/protected
    •      . . 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
      •      . . . . C.2.b.1 Length of stream made accessible
      •      . . . . C.2.b.2 Square miles of streambed made accessible (Square miles)
      •      . . . . C.2.b.3 Type of blockage/barrier (LOV)
      •      . . . . C.2.b.4 Number of blockages/impediments/barriers impeding passage
      •      . . . . C.2.c.1 Fish passage blockages removed or altered (other than road crossings reported in C.2.f to C.2.i)Y (Y/N)
        •      . . . . . . C.2.c.2 Number of blockages/impediments/barriers removed/altered