Background on the Tucannon River:  The Tucannon River basin is located in Southeast Washington State in Columbia and Garfield counties.  The system-wide restoration objective for the Tucannon River is to improve habitat conditions for Endangered Species Act (ESA) listed species (Snake River Spring Chinook and Steelhead) for all life history stages.  It is expected that improved habitat conditions will lead to an increase in the abundance of listed species returning to the river.  Increasing abundance will lead to de-listing of the species, which is the overall recovery goal for the system.  Previous efforts (CCD 2004; SRSRB 2006) have identified the habitat-limiting factors associated with the decline of ESA-listed populations.

Summary:  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 treatments include construction of instream habitat features such as engineered log jams (ELJs), removal of infrastructure such as spoils material and artificial embankment, and the installation of riparian plantings.  The principal benefits of project implementation will be restoration of historic spring Chinook spawning, rearing, and migration corridor habitats.  The associated treatment of riparian areas is expected to induce naturally occurring repair, restoration, and recovery of both floodplain and riparian zone function and processes.

Project Design Phase:  This contract (Year-1) would be to complete: a final assessment, design report, project design, implementation cost estimate, any subsequent design modifications (following review), and the initiation of permitting including environmental and cultural resources clearances, if possible.

Background:  Under prior contracts, the Columbia Conservation District (CCD) coordinated the completion of the Tucannon River Habitat Assessment (Anchor Aug 2011) which led to the development of the Tucannon River Conceptual Restoration Plan (Anchor Nov 2011) from RM-30 upstream to RM-50.  The Conceptual Restoration Plan (Anchor QEA, 2011) has prioritized projects into three Tiers (1-3) based on the projected effects of implementation as a benefit to Snake River spring Chinook, cost-efficiency relative to those benefits, and the feasibility of construction.  

Project Area Summary:  Project Area 24 (PA-24) is located within the active river channel and floodplain of the Tucannon River, on private land from the bridge at RM-28.25 to approximately RM-27.5.  The project is identified as a Tier-1 project in the Conceptual Restoration Plan (Anchor QEA, 2011) developed for the Tucannon.  The primary objectives of the project are to increase floodplain connectivity through removing channel confining features and improve channel complexity through placement of large wood debris in the form of constructed log jams.

Prior Design Phase:  The PA-24 project was previously designed to a 30% level, as part of a grant held by the SRSRB [Walla Walla Community College (WWCC).  The SRSRB received state Salmon Recovery Funding Board (SRFB) money to advance priority Tier-1 projects (from the Conceptual Restoration Plan) to a 30% design-stage during the 2012 field season which resulted in the completion of PA-14 final designs, PA-15 to a 30% design and PA-24 to a 30% design.  PA-14 (final design funded by SRFB) and PA-15 (Final Design Funded by BPA #58975) are currently at final design and are scheduled for implementation in 2014.  The 30% Design Plan for PA-24 began to describe the purpose, function, design, and construction of restoration treatments that are proposed for implementation in this river segment; and it is attached to the SOW in Pisces.  

Pending Design Contract:  The current 30% design focus for project Area 24 is on increasing in-channel complexity through the placement of LWD, and reducing channel confinement through the removal of channel confining features. Pursuant to BPA contract funding for the Tucannon Habitat Programmatic in FY14, the Snake River Salmon Recovery Board (SRSRB) is advancing the development of this restoration design to a near-final (90%) Plan and Report, expected to be completed by the summer/Fall of 2014.  During this period, staff will also begin to initiate and coordinate permitting requirements and environmental clearances for the Project Area 24 project, in anticipation of design implementation and project construction in the summer of 2015.  

Future Implementation Phase to Begin in 2015 Work Window:

The next contract (Year-2) would be to complete: any final permitting, environmental and cultural resources clearances, and implementation of the design (construction of improved habitat features, and actions to restore ecological function).

Expected Implementation Actions (from the 30% Conceptual Design):  Reconnect isolated habitat within several areas with the project reach through the removal and set back of river levees.  Remove and set back approximately 2,530 feet of levees in three locations to re-establish floodplain connectivity to approximately 1.32 acres of low floodplain.   Install ELJs and other LWD to increase channel complexity over a ¾ mile reach.  Re-plant adjacent floodplain and riparian areas; re-vegetate and restore disturbed construction access sites and staging areas.  

Geomorphic Implications:  Setting back infrastructure will allow a wider corridor for channel migration and accessible floodplain area. Increased connectivity with the low-lying floodplain will lead to decreased channel velocities during high flows and dispersion of sediment across the floodplain.  Addition of LWD will initiate a geomorphic response resulting in bed scour and sorting of sediment, which forms critical habitat features (e.g., pools, cover, and spawning gravels).  Because the channel profile is controlled by man-made features and bedrock, the wood placements are not expected to significantly affect the channel grade. However, the ELJs will 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 network by splitting flow, initiating gravel bar and island development, and promoting channel migration within the reconnected floodplain area.

Biological Benefits:  Immediate biological benefits of the project include decreased instream velocities during high flows from better connectivity with the floodplain, and pool development and cover provided by the LWD placements. 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, greater floodplain connectivity will also lead to a healthier riparian zone and, in turn, promote improved ecosystem processes and habitat function.

Potential Challenges: Multiple access points will be necessary to place LWD and remove infrastructure. These actions will disturb some existing trees and other vegetation. The project design will require the landowner’s acceptance.