Background: The Tucannon River in Southeast Washington flows north out of the Blue Mountains into the Snake River, and is the ancestral boundary between the Confederated Tribes of the Umatilla Indian Reservation and the Nez Perce Tribe. The Tucannon watershed supports the only remaining population of spring Chinook (Oncorhynchus tshawytscha) in the lower Snake River. Early fish estimates show the Tucannon once produced thousands of salmon annually, but now only produces a few hundred adult spring Chinook each year. In 1992, spring Chinook were listed as threatened under the Endangered Species Act as runs declined to less than 200 adult fish. Because of the Tucannon River’s importance to the Snake River Basin, BPA provides funding for a Programmatic Habitat Project in the Tucannon River.

The Tucannon Programmatic Project is managed by the Snake River Salmon Recovery Board (SRSRB) through a parent contract for operational support, organizational management, implementation assistance, and annual reporting. The goal of the Tucannon River Programmatic is to restore natural channel processes in priority restoration reaches of the Tucannon River, leading to improved population productivity and abundance for ESA-listed steelhead, spring Chinook, and bull trout. The Tucannon River basin is considered a priority subbasin for listed salmonid habitat restoration per the 2020 NOAA CRSO BiOp and its supporting documents (Endangered Species Act Section 7(a)(2) Biological Opinion and Magnuson-Stevens Fishery Conservation and Management Act Essential Fish Habitat Response for the Continued Operation and Maintenance of the Columbia River System, July 2020).

The NPT collaborates in the Programmatic Project as a project implementer in support of programmatic goals, consistent with the NPT restoration vision: a desired riverine system that is shaped and maintained by the dynamic interactions and interconnections of its natural physical and ecological processes. The restoration actions proposed for implementation in the prioritized river segments 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 throughout the project reaches proposed for treatment in the watershed include:  

•    Past land use practices including logging, livestock grazing, irrigated agriculture, and recreational development (e.g., construction of the Tucannon Lakes), in addition to recent large forest fires in the headwaters, have created conditions in the Tucannon River that have over-simplified the stream channel and drastically reduced the productivity, abundance, and sustainability of native salmonid populations.  
•    Channel simplification caused by channel confinement (levees, lakes, roads) and straightening (pushing the channel to the valley wall) has led to a loss of floodplain connectivity and an increase in channel incision, increased stream velocities, and loss of pool habitat. These factors have combined to decrease quality habitat for adult and juvenile Spring Chinook salmon, steelhead, and Bull Trout, leaving these unique populations at risk.

Overview: The 2011 Tucannon River Geomorphic Assessment & Habitat Restoration Study (Anchor QEA, April 2011) identified and prioritized stream reaches and restoration actions which would best improve habitat for salmonids. The prioritized work focused on RM-20 upstream to RM-50. In 2018, through the Tucannon River Programmatic Habitat project, the Restoration Plan was updated to include the Tucannon River from RM-20 downstream to the confluence with the Snake River.

The 2021 Tucannon Conceptual Restoration Plan (Anchor QEA, 2021) prioritizes projects into three Tiers (1-3) based on explicit prioritization goals:  (1) increased complexity at low-winter flows, (2) increased complexity during spring and winter peak flows, (3) re-connection of disconnected and abandoned floodplains, (4) improved quantity and quality of pools, and (4) increased retention and storage of in-channel bedload sediments. With these prioritization goals, the Tucannon Implementers (e.g., SRSRB, NPT) select project areas in the Tucannon that focus on increasing habitat condition for adult and juvenile Snake River spring Chinook, steelhead and Bull Trout. The prioritization goals
ensure that project areas for restoration actions are selected to be large enough to make a meaningful difference, be cost-effective relative to those benefits, and remain feasible to construct.

Current Emphasis: Tumalum Creek is a major tributary to the Tucannon River, and supports ESA-listed Snake River summer steelhead, Snake River Spring Chinook, bull trout, and other native aquatic species. Tumalum Creek enters the Tucannon River at approximately RM36. The culvert conveying Tumalum Creek under Tucannon Road has a narrow upstream passage flow window that is depth-limited at low flows and velocity-limited at high flows, impeding fish passage for both juvenile and adult salmonids. The culvert outlet is perched at low flow and its bottom lacks any substrate. The culvert also limits extreme flood conveyance, which is a concern for adjacent landowners and Columbia County (which maintains the bridge and proximate road prism).

The Tumalum Project Area is located within the active river channel and floodplain of Tumalum Creek, on private property. The project entails replacing the 65-foot long 10-foot wide corrugated metal arch pipe culvert with a 60-foot long 15-foot wide four-sided concrete box culvert, following WDFW’s stream simulation design guidelines. A four-sided box culvert was selected over a three-sided culvert or bridge to avoid need for foundation work and to minimize construction time. In consideration of the prevailing slope in the project reach, the streambed design includes small steps composed of coarser substrates similar in size to upstream and downstream of the culvert location. Logs with rootwads will be installed interlocked with existing trees downstream of the culvert to provide holding habitat and reduce velocities upstream in the culvert to support step stability. Columbia County roadway safety design requirements will be included as part of the project.

NPT will partner with Columbia County to replace the Tumalum Creek culvert. The County will contribute cost share by providing a construction crew, equipment, and field engineering and supervision.

Note: This project was initially designed and planned for implementation in 2019-20 (#74017 Rel 70 and Rel 100) for implementation in 2022.