Background:  The Walla Walla River basin is located within the ceded-area of the CTUIR in Southeast Washington (Columbia and Walla Walla counties) and Northeast Oregon (Umatilla county). The Walla Walla River is home to two Endangered Species Act (ESA) listed fish species: Middle Columbia River summer steelhead (Oncorhynchus mykiss) and Bull Trout (Salvelinus confluentus). The system-wide restoration objective for the Walla Walla River is to improve habitat conditions for ESA-listed species, for all life-history stages, as well as for other culturally and economically important species including spring Chinook salmon (O. tshawytscha) and resident redband Rainbow Trout (O. mykiss gairdneri).  It is expected that improved habitat conditions for listed species will lead to an increase in the abundance and productivity of all species returning to the river.

The Walla Walla River Basin Fish Habitat Enhancement Project (#1996-046-01) is an ongoing effort to monitor, protect, enhance, and restore the natural form and function of the river, floodplains, and native fish habitats throughout the watershed. Restoration project locations and selection criteria are derived from various managerial guidance documents and based upon identification and addressing factors limiting salmonid production including the Middle Columbia River Steelhead Recovery Plan (NMFS 2009), Bull Trout Recovery Plan (USFWS 2015), Walla Walla Subbasin Plan (NPCC 2004), Umatilla River Vision (Jones et al. 2008), Lower Walla Walla River Geomorphic Assessment and Action Plan (CTUIR 2014), and the Lower Mill Creek Final Habitat and Passage Assessment and Strategic Action Plan (CTUIR 2017). The Project is responsible for improving physical habitat conditions for ESA-Listed salmonid species.  

The headwaters of the mainstem Walla Walla River have sustainable cold water habitats available to support salmonids and other native fish. Access to and the availability of cold water habitats are essential for improved productivity and abundance, necessary for maintaining and sustaining rebuilding fish populations, and imperative for de-listing and recovery of harvestable populations of ESA-listed steelhead and Bull Trout and recently reintroduced spring Chinook salmon.

Additionally, as part of the Columbia Basin Fish and Wildlife Program, BPA is funding construction of a new spring Chinook salmon hatchery facility, located 10 miles southeast of Milton-Freewater, Oregon, on the South Fork Walla Walla River. Nearly completed, the hatchery is expected to return thousands of adult spring Chinook salmon to tributaries throughout the Walla Walla River Basin each year. Twenty nine miles of adult spring Chinook salmon spawning habitat exists upstream of the flood control project at Nursery Bridge. Improved passage, habitat, and flows are essential for meeting the restoration goal of re-introduced spring Chinook salmon, which includes river access for harvest and natural production above the hatchery location and the project reach.

Overview: Since 1996, the Confederated Tribes of the Umatilla Indian Reservation (CTUIR) has managed the Walla Walla River Basin Fish Habitat Project through an overall contract for program operations, management organization, project development, implementation assistance and progress reporting in support of restored access to and utilization of these available, productive cold water habitats. The goal of the CTUIR habitat program in the Walla Walla is to restore function and natural channel processes in the summer Steelhead and spring Chinook priority restoration reaches of the River, leading to improved population productivity and abundance (noted above).

The CTUIR manages this contract as a contribution in support of Fish & Wildlife Program goals for the watershed, consistent with the CTUIR River Vision: a desired riverine system that is shaped and maintained by the dynamic interactions and interconnections of its natural physical and ecological processes. The passage restoration and habitat improvement actions proposed for implementation in these prioritized river segment promote and enhance the interconnected nature of the five primary touchstones of the Tribes' Vision: a) hydrology, b) geomorphology, c) connectivity, d) riparian community, and e) aquatic biota.  

Major limiting factors influencing the condition of these touchstones proposed for treatment within the Nursery Bridge project reach include:  
  • Anthropogenic modifications affecting and causing the loss of natural channel forming processes that link the Walla Walla River to its floodplain;
  • Loss of key in-channel habitat complexity and structure, including diversity and quantity, especially in the form of gravel sorting, varied velocities, and pools associated with recruitment of large wood;
  • Reduced flow volume and duration, and elevated summer water temperatures; and
  • Passage restricted or blocked by accumulated cobble deposits and a seasonally-constructed irrigation diversion berm.
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Project Area Summary: The narrow, highly energetic Walla Walla River within the Milton-Freewater Levee Project reach does not function well as an ecosystem that provides valuable habitat or reliable passage conditions for Endangered Species Act-listed fish and other aquatic species.  

In 1951, the US Army Corps of Engineers constructed the Levee Project to provide flood risk reduction for the city of Milton-Freewater and the surrounding area. With the energy of the Walla Walla River confined within the levees, the Levee Project was breached during the 1964-65 floods. The US Army Corps of Engineers repaired the levees in 1967 by installing larger rock facing on the levee footings and constructing a 14-foot tall drop structure downstream of the Nursery Bridge crossing at Eastside Road, to stabilize bridge footings.

Below the drop structure, the River has no connectivity with its floodplain, very little riparian vegetation to maintain summer water quality, limited complexity necessary for high-quality aquatic habitat due to the confined nature of the channel, and a continuously degrading channel that threatens to permanently disconnect fish passage at and below the drop structure. Upstream of the drop structure, the channel is less confined in many places, but lacks complexity and is disconnected from its floodplain; at the drop structure, the current alignment of the channel does not allow reliable connectivity of the main channel with the east fishway exit.

Responding to the 1996 Endangered Species Act listing of Middle Columbia River summer steelhead, and the 1999 ESA listing of the coterminous population of Bull Trout, a new upstream fish passage facility was constructed on the east side of the drop structure in 2001. The east fishway was constructed to provide volitional passage for all life stages of ESA-listed fish species, which the original west fishway did not provide. The east fishway also contains fish counting and brood collection facilities intended to support the CTUIR South Fork Walla Walla Hatchery and the continuing reintroduction of spring Chinook salmon to the Walla Walla River.

As the project area has experienced flood flows over the years, the levees and drop structure have required frequent maintenance and repairs, in large part due to the channel below the drop structure continuing to downcut and degrade. The highly energetic river channel in the leveed reach creates extreme stress on the channel bottom causing increasingly unfettered channel degradation and incision. Since construction of the Project and by 2014, the channel has downcut over 11 vertical feet, exposing the levee toe and narrowing the width of the channel from the dimensions as originally designed – for conveyance flows that have increased in velocity and shear-stress because they have become increasingly narrowed and constrained.

A flood event in 2013-14 again caused significant downcutting downstream of the drop structure which disconnected the east fishway entrance and rendered the drop structure impassable by ESA-listed fish species. The Walla Walla Basin Watershed Council, CTUIR, Bonneville Power Administration, and the Milton-Freewater Water Control District cooperated to construct an emergency grade-controlled channel to regain functional fish passage at the east fishway entrance in the summer of 2014. However, the work did nothing to address the ongoing downstream channel incision, unconstrained in the conveyance channel below the grade-control structure.

In much of the middle and lower Walla Walla River today, water is sparse and fish habitat has been compromised due to out-of-stream water-use and channelization and simplification of the stream corridors. The Levee Project is seriously impacting fish passage and habitat, floodplain connectivity, and water quantity and quality. The drop structure and hydraulically controlled flow conditions sustain channel degradation and directly promote incision, varied water temperatures, and loss of stream flow volume (seepage). Lack of progress in addressing the conditions in the flood control project reach is creating an increasingly hardened “fish restoration bottleneck” for Steelhead, Bull Trout and spring Chinook salmon.

Objectives: Correcting the environmental deficiencies of the Project has been prioritized in numerous subbasin plans, including the National Marine Fisheries Service’s (NMFS) Mid-Columbia Steelhead Recovery Plan and Columbia Bull Trout Recovery Plan under the Endangered Species Act, and recent river assessments and strategic action plans. The NMFS emphasized to the U.S. Army Corps of Engineers in 2012 and 2014 letters that ecosystem recovery actions in the project reach are necessary and offer the greatest potential for improvement to ESA-listed steelhead population viability and de-listing.

The project-level objectives for Nursery Bridge supported by this contract are to improve the river channel within the 5-mile Milton-Freewater Levee Project reach to: recover floodplain-riverine processes, restore and maintain fish passage, stop channel incision, enhance rearing and over-wintering habitat, and decrease surface water seepage – while not impacting flood risk management or restricting flood flow-conveyance.
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Contract Summary: This contract continues the CTUIR role anticipated in the Accords (BPA) and the Walla Walla Habitat Project for progress in improving habitat conditions in the watershed at Nursery Bridge: to inform and conduct project evaluation, selection, management, implementation planning, data collection, monitoring, outreach and other tasks, where tribal staff can provide expertise; and to be an implementer of the on-the-ground project construction activities for the project components identified and selected as a priority for implementation.

Contract tasks include identifying and sequencing projects for implementation pursuant to the prioritized restoration strategy for the Nursery Bridge reach, and consistent with the Tribes' First-Foods paradigm and River Vision principles; the CTUIR and BPA staff will partner with stakeholder-participants and others to implement the prioritized project elements. This yearly contract may also support development of additional habitat project concepts, refinement of restoration approaches, the production of revised engineered designs for ongoing projects, implementation work-planning, construction scheduling for approved projects, and the build-out of selected projects.

  • Ongoing: In 2016, the CTUIR began a collaborative design effort to develop a long-term solution for fish passage at the drop structure and to address the persistent downcutting in the conveyance channel below the drop structure. Analyses completed during this design period indicate that the hydraulic conditions downstream of the drop structure are such that material or structures placed in the channel are unlikely to halt channel degradation or continued incision and encourage channel aggradation. CTUIR staff continues to consider alternatives and maintains watershed coordination with the Water Control District, USACE, SRSRB, ODFW, WDFW, WWBWC, Irrigation interests, and BPA, through ongoing communication and collaboration, shared work-tasks, and monthly and quarterly meetings.

The CTUIR continues project development efforts and implementation tasks addressed to improving habitat structure and passage function above and below the grade control structure at Nursery Bridge, and throughout the Walla Walla watershed. Major tasks to be completed by the CTUIR project staff during this contract term include: ongoing planning, design and coordination for habitat and passage improvements in the Levee Project reach of the Walla Walla River at Nursery Bridge: 1) complete Phase II Final Design; 2) advance Phase III to 30% design stage; and 3) develop Implementation & Monitoring Plans, Staking, Oversight, As-Built, and Site Plan.

  • Current: Habitat project development, design, and implementation planning in the current contract period emphasizes actions designed to address the deficient fish passage and habitat characteristics, and the degraded conveyance capacity and function, of the flood control project reach. Design elements incorporate measures to improve floodplain function, channel form and process, fish passage, instream habitat complexity, and overall water quality and quantity.

(a) Phase II: The design development process for actions to: a) reconfigure the channel alignment and add complexity or roughness elements for habitat function above the drop structure; and b) address restricted or impeded fish passage conditions for the eastside fishway at the drop structure is ongoing but requires additional evaluation and refinement at the 60% design iteration. CTUIR and BPA contract staff continue to plan for implementation of the Phase II components of the overall project; construction is expected to begin during the Summer of 2022.

(2) Phase III: Design measures to address the broader flood control project concerns of floodplain function and channel form and process in the downstream conveyance reach, that continues to downcut below the drop structure, has been initiated but held to: a) concept development, b) alternatives analysis, and c) a subsequent 30% design iteration.

Descriptions of the project areas with respect to existing natural processes and habitat conditions to be addressed are provided in the associated project Design Reports, along with the specific physical and biological objectives that the proposed restoration features are expected to achieve for each phase of the design and build-out of the project areas in the Levee Project reach.