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 the spring Chinook priority restoration reaches of the Tucannon River, leading to improved population productivity and abundance. The CTUIR collaborates in the Programmatic Project, as a project implementer in support of programmatic goals, 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 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 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 the spring Chinook population.  
•    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 (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: After several years of opportunistic restoration in the Tucannon Basin, as a Model Watershed (1997-2008), the Columbia County Conservation District (CCD) brought all parties to the table to work on a new restoration planning document. The 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. Refocusing on the high priority areas for spring Chinook, the CCD coordinated the development of a habitat restoration plan that prioritized work from RM-20 upstream to RM-50. After 10 years of implementing the first plan, it became obvious that program managers needed to move further down the watershed and start working in the lower Tucannon River. In 2018, through the Tucannon River Programmatic Habitat project, the CCD initiated an update of the Tucannon Restoration Plan to help refocus restoration efforts and include the rest of the Tucannon River from RM-20 downstream to the confluence of the Snake River.

The Updated Tucannon Conceptual Restoration Plan (Anchor QEA, In Process) will prioritize projects into three Tiers (1-3) based on these 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 new prioritization goals, the Tucannon Implementer will 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 refocusing of prioritization goals will ensure Tucannon Implementer are selecting project areas for future restoration actions that are large enough to make a meaningful difference, be cost-effective relative to those benefits, and remain feasible to construct.

Project Area Summary: Project Area (PA) 17 is located within the active river channel and floodplain of the Tucannon River, on private property from RM-36 to RM-35 (approx). The project is identified as a Tier-1 project in the Conceptual Restoration Plan (Anchor QEA, 2011) developed for the Tucannon River. The primary objectives of the project are to increase floodplain connectivity through: removing channel confining features, increasing off-channel and reconnecting side-channel habitats; and improving channel complexity through placement of large wood debris in the form of constructed log jams and single-log wood placements.

Status (FY20): The project is currently in the design phase (see contract #73982 REL42); CTUIR project staff are working with the private landowners and design subcontractor through 2020, to be ready for implementation as early as Jul 2021.CTUIR will lead the implementation management and supervision for: pre-construction site preparation, permitting, and design finalization at PA-17. Restoration actions proposed for the project area are identified in the Updated Tucannon Conceptual Restoration Plan as a high priority for habitat improvements (Anchor QEA, Nov 2011), and focus on increasing the amount of large wood debris (LWD) to increase channel complexity and floodplain connectivity, the highest priority actions for spring Chinook in the Tucannon.

Project Elements (PA-17): Description of the project areas with respect to existing natural processes and habitat conditions will be provided in the associated project Design Report, along with the specific physical and biological objectives that the proposed restoration features are expected to achieve for each phase of the design/build for the project areas. The design focus for the project area is on improving the multiple habitat structure, floodplain connection, and stream function deficiencies associated with this reach of the Tucannon River. Enhancing and restoring instream habitat in this project area will be accomplished through a variety of treatment actions in the main channel, along the banks, and within the floodplain. These design features are intended to benefit spring Chinook by providing better refuge and spawning habitat for adults, reducing redd scour during winter flood events, and increasing rearing habitat and over-winter survivals for juvenile salmonids.

Expected Implementation Actions (from the Design Report): Install eleven instream and sixty floodplain LWD structures or wood placements in the main channel and low floodplain to increase channel complexity over a 0.6 mile reach. Additional unsecured mobile LWD will be placed in the main channel, side channels, and on the floodplain for complexity. Reconnect isolated habitat in several areas within the project reach through the removal or breaching of gravel berms through pilot cuts, to re-establish floodplain connectivity to approximately 14 acres of low floodplain. Plant adjacent floodplain and riparian areas, and where disturbed, re-vegetate and restore construction access sites and staging areas. Planting efforts will emphasize an increase in pines and cottonwoods throughout the reach for the purpose of future LWD key piece recruitment.

Geomorphic Implications:  Reconnecting floodplain will allow a wider corridor for channel migration and accessible floodplain area. Increased connectivity with the floodplain will lead to decreased channel velocities and dispersion of sediment across the floodplain during high flows.  In addition, LWD will initiate a geomorphic response resulting in bed scour and sorting of fine and medium grained sediment, which forms critical habitat features (e.g., pools, riffles, and spawning habitat).  Because the channel profile is controlled by man-made features and has aggraded to bedrock, the wood placements will capture sediments and affect the channel grade. The ELJs will also influence the development of additional pools and depositional areas in the plane-bed sections of the channel. In addition, large wood structures will promote development of a more complex channel networks throughout this reach by splitting flow, initiating gravel bar and island development, and promoting channel migration within the reconnected floodplain area.

Biological Benefits:  Increasing the amount of LWD in channel will provide increased roughness elements increasing the connectivity with the floodplain, providing instream pool development and gravel for riffle habitat for spawning. Immediate biological benefits of the project include decreased instream velocities during high flows to provide better rearing habitat for juvenile salmonids.  As the channel is able to establish a more complex planform through the reconnected floodplain, more diverse habitat areas will be available to increase the carrying capacity for juvenile salmonids. Deposition of sediment and formation of side channels will create additional spawning area. Over time, the greater floodplain connectivity will also lead to a healthier riparian zone and, in turn, promote improved ecosystem processes and habitat function.