Dillwater LWD Enhancement

The Dillwater LWD Enhancement project, located between River Mile 21.2 and 21.4 on the Entiat River, was constructed to improve habitat complexity by construction of 4 Engineered Log Jams (ELJs) in the main channel and along the banks and one in the side channel. This project is located in the “Stillwater Reach” which will be intensively monitored for fish response to restoration activities by the ISEMP Program. The upper sub-basin is considered a Category 1 Watershed and is also a critical spawning area for Federally Endangered spring Chinook, Threatened Upper Columbia River steelhead, and Threatened bull trout. This project has direct benefits to a 1/3-mile reach on the mainstem, improve habitat conditions in a 1,100 ft side-channel, and affect approximately 13 acres of connected riparian floodplain. This project also included 1.5 acres of riparian plantings with various native species. The USBR Preston Reach Assessment recommends the addition of large woody debris in this reach as a habitat improvement action and the REI indicates an “at risk” condition for this habitat element. The Dillwater ELJ structures are intended to create habitat by adding stream channel complexity elements, particularly for juvenile fishes, and to afford high-flow refugia. In addition, they would be effective at sediment storage which is needed to reduce lateral stream channel instability. USFWS data shows that a high local sediment supply (from upstream bank erosion), coupled with high width-to-depth ratios, has resulted in an enlarging channel and instability is exaserbated by limited riparian vegetation upstream.

The goal of this project is to place LWD between River Mile 21.2 and 21.4 on the Entiat River, aiming to improve habitat complexity by construction of 4-5 Engineered Log Jams (ELJs) in the main channel and along the banks. This project is located in the “Stillwater Reach” which will be intensively monitored for fish response to restoration activities by the ISEMP Program in 2011.