Greenwater River Flood Plain Restoration

The Greenwater River can be found in the Mt Baker-Snoqualmie National Forest. It is one of the largest producers of Spring Chinook, coho, pink, and steelhead in the upper White River Watershed. This project is a reach-scale restoration effort to restore lost functions of floodplain connection and in stream wood structure. The project seeks to re-introduce stable wood into the main stem of the river to increase channel complexity, sediment deposition and natural accumulation of LWD during high flow events. The design process began at the watershed scale before focusing on the stream channel. A twelve step design process was followed that considered the influence of watershed disturbances on channel forming process.

 Historical practices along the Greenwater River resulted in a loss of salmon habitat. Logging practices between the 1950s and 1960s removed a significant amount of mature wood from the valley. The system destabilized, as banks eroded and wood and logging slash washed downstream. Deforestation and unstable banks played a major role in the 1977 flooding of Greenwater. Prior to the completion of this project the river had few pools, little rearing habitat, and almost no functional streamside cover.

The project removed nearly a mile of abandoned forest road fill and armor from the floodplain. The road previously disconnected the river from its historic floodplain channels and confined the river to the point of channel incision. In conjunction with road removal activities, the project also added 14 large engineered log jams (ELJs) to the river at strategic locations to slow flood flows, accumulate and sort gravels, and deflect flows into relic floodplain channels. Ultimately, the project removed nearly 70,000 cubic yards of road fill and large armor rock from the Greenwater floodplain and added over 2.700 pieces of wood to the 3 mile stretch of river. 

Restoration efforts combined with protection practices and supplemental Spring Chinook enhancement programs managed by the Forest Service, Puyallup Tribe, and Muckleshoot Tribe should yield a highly functional spawning and rearing ground for Puyallup/White River salmon stocks.

SPSSEG is spearheading an effort to continue and further develop a monitoring program to evaluate and measure the success of this project. Start-up funds have been secured to measure baseline and first-year post-project results. However, SPSSEG is seeking additional resources to continue this effort.

This project was funded by SRFB, WSDOT, and the USDA Forest Service.