The Project Area (PA) 26 proposal is a large woody debris project, located on private property with the goal of increasing river channel roughness and floodplain connectivity within a 3.7 mile long reach of the Tucannon River, in Columbia County (RM 23.1 - 26.8).   LWD will be placed in channel at locations and in orientations to increase floodplain connectivity in areas where previous levee removals/modifications were implemented in 2011, as part of a previous project (identified as Phase I and implemented under project 1984-018-06, Contract 50146).  The overall project area (3.7 mile reach) will be broken out into a number of implementation work windows based on funding, landowner participation and adaptive management needs.  Phase II (CR-340020) being proposed in 2020 is targeting the upriver most 0.8 river mile.

Background:  In 2011, river levees and gravel berms were removed or breached throughout the entire reach as part of the 3.7 mile long PA 26 Phase I project.  The goal of Phase I was to restore properly functioning geomorphic condition by reducing river channel and floodplain confinement.  In 2011, levee removal was a new and innovative restoration technique for SE Washington State, and it was determined that a conservative approach would be implemented where the levee would be removed and set back and channel modifications would be delayed to make observations on how the channel would recover naturally (letting the river do the work).  Based on observations made by 2013, five log jams were placed within the upper 0.8 mile reach to provide fish cover while observations were continued.  Monitoring surveys conducted by CHaMP and the Tucannon Habitat Programmatic between 2012 and 2017 indicated limited change in channel shape or gravel storage within the reach and that the ~14 ac of floodplain liberated by the 2011 levee removal project had experienced very limited flood inundation.  The CHaMP program recommended addition LWD structure placement to sort and retain gravel bars to encourage lateral channel migration and increased floodplain inundation frequency and duration. The Phase II proposed work (CR-340020) is located on the upper ~0.8 miles of the project reach on which restoration actions were performed in 2011 & 2013 Phase I and is the first significant log jam project to be proposed for implementation following the CHaMP recommendations.  

Problem Statement:  Geomorphic processes, floodplain connectivity, and accompanying habitat for spring Chinook and summer steelhead within the reach have been influenced by historic land use practices, tree harvest/clearing, and excavation and other bulk earthwork activities at various locations within the 100-year floodplain.  These activities have led to limited instream and floodplain habitat complexity, degraded floodplain connectivity and riparian condition, elevated summer water temperatures, and elevated embeddedness all key habitat limiting factors for Chinook and steelhead (Anchor QEA 2011a). This project aims to address many of these factors through stream restoration and habitat enhancement which would lead to natural functioning conditions.  

Project Goals and Objectives: The primary goal of the proposed project is to restore to the nearest possible extent a healthy naturally functioning river channel and floodplain.  This goal is set within the context of adjoining active agricultural production fields and infrastructure supporting those activities.

Phase II Objectives:
•    Place 28 instream LWD structures to increase channel complexity and increase floodplain connectivity
•    Place 15 Floodplain Roughness LWD structures to increase floodplain sediment storage and complexity.
•    Increase flood frequency and duration to about 14 acres of floodplain.

Ongoing habitat restoration work within the project area would be include in Phases III or additional future project Phases based on the available habitat restoration needs and adaptive management actions.  Anticipated work in future phases may include the placement of log jams within the active river channel and on the floodplain for the purpose of improving river and flood plain function in support of ESA listed salmonid habitat limiting factors.  Future phases may include improvements to stream crossing, removal of additional floodplain confining features, reconnecting disconnected channels, the placement of additional or modification to log jams, planting riparian trees and treating invasive plant spps.  Adaptive management actions for this project reach will target maintaining the project restoration goals of improving channel complexity and floodplain connectivity.  Observations of improperly functioning or unintended geomorphic outcomes made during site visits by the CCD either as scheduled or requested by the landowner, will be reviewed by the CCD and the Tucannon Habitat Programmatic (2010-077-00).  Based on the site specific outcomes, management actions would be designed and implemented to realign conditions to the project goals.

Note:  The CCD has been awarded a SRFB grant in the SRSRB 2019 grant round to support implementation in part as match to this project implementation in 2020-2022 (for more detail on this grant is provided in the detail budget attached to CR-340020)  The grant proposal can be viewed on the RCO PRISM online (grant number 19-1494).