Cle Elum River Instream Habitat and Side Channel Restoration Project
The Lower Cle Elum River Instream Habitat and Side Channel Restoration Project encompasses two separate planning and implementation phases aimed at improving spawning and rearing habitat conditions in a highly regulated reach of the Cle Elum River. A majority of this project is located within a conservation easement that KCT holds for its unique habitat values.
Habitat conditions within Lower Cle Elum River have been significantly impacted from flow regulation and operations of the Cle Elum Dam. The results of this flow regulation result in a dramatic decrease in peak flow events, which typically responsible for bed and bank erosion that allows the river to move and meander across its historic floodplain. This lack of movement and natural high flows has also curtailed the recruitment of sediment and large trees within the floodplain, causing this portion of the river to be largely devoid of pools and other hydraulic complexity that provides habitat for salmonids. Side channels that were once perennial have become more intermittent and incised, as their inlets have become perched above the height of main river channel. The adjacent floodplains receive floodwaters less frequently as a result of this incision.
The first phase of this project, located from river miles 5.25 to 7.2, was completed in 2009. This phase included construction of two engineered log jams (ELJs) and some minor excavation that introduced perennial flow to over a mile of the river's right bank floodplain in the area of Domerie Creek. Initial monitoring indicated that this work more than tripled the amount of juvenile salmon "hiding" areas and helped decrease water temperatures during low-flow summer conditions in the main river channel (Cardno 2013).
KCT built upon the success of the 2009 project with Phase 2 in 2014. This include construction of 8 main stem ELJs and 2 side channel ELJ's, placement of 30 anchored tree snags in the main river channel and 30 individual unanchored snags in side channels, excavation of 4 side channel inlets and construction of 4 gravel bars. The project utilized both conventional ground based and helicopter assisted construction mechanisms. All but one of the ELJ's and the 30 anchored snags were constructed utilizing a Vertol 107 helicopter, which significantly minimized disturbance of critical wetland areas. A total of 5 miles of side channel habitat and 240 acres of floodplain was reconnected to the Cle Elum River at completion of the 2014 project. For detailed information on this project, including site maps, project designs, and additional photos, click on the reports, maps, and project snapshot links on the left.