Lower Cle Elum River Restoration Project

The Lower Cle Elum River Instream Habitat and Side-Channel Restoration Project is a two-phase project that improved spawning and rearing habitat for native salmon and trout species on the stretch of the river beneath the Cle Elum Dam. The project is located within the conservation easement lands that KCT stewards for its unique habitat values.

Floodplain Reconnection

The Cle Elum Dam regulates the flow of the Lower Cle Elum River, which significantly impacts the quality of the river habitat. Flow regulation dramatically decreases flooding, otherwise known as peak flow events. While humans tend to view flooding as bad, it is what supports a healthy ecosystem. Flooding is responsible for replenishing the floodplain “sponge,” or groundwater table, which provides the stream clean, cold water year-round.

In a healthy system, the river moves and meanders across its floodplain creating a beautiful mess that provides habitat for all sorts of fish and wildlife. But when humans control the flows of the river, it stops moving around. Since it no longer moves around, the river slowly cuts down into the bed. Water isn’t pushed out onto the floodplain so trees do not fall into the stream and sediment becomes stationary. As a result, this portion of the river is largely devoid of pools and other complexity that provides good habitat for native fish and wildlife.

Moreover, side channels that once flowed year-round only had water in them for part of the year. Since the river cut down into the bed, the inlets of the channels were perched above the river. Once above the main river, water no longer flowed into the channel, cutting off fish and other creatures from accessing this important habitat.

Adding Miles Of Habitat

Because this was a large-scale project it was broken out into multiple phases through different grants:

06-2141 RST, Cle Elum River Instream Habitat – Phase 1 | Funding: $381,820 | Completion Date: 6/30/2010
11-1564 Cle Elum River PH-2 Instream Habitat Design – Phase 2 | Funding: $172,000 | Completion Date: 8/8/2013
13-1314 Cle Elum River Side Channel Restoration PH 2 – Phase 2| Funding: $1,087,211 | Completion Date: 6/15/2015 | Funding from DOE/RCO YBIP, MMF, USFWS)

Phase 1

We completed the first phase of this project in 2009. This section was located from river miles 5.25 to 7.2. We constructed two engineered log jams (ELJs) and did some minor excavation that reconnected year-round (perennial) flow to over a mile of the river’s right bank floodplain near Domerie Creek. After completion, we went back out to look for any changes. We found that the work more than tripled the amount of juvenile salmon “hiding” areas. In addition, it decreased water temperatures during low-flow summer conditions in the main river channel (Cardno 2013).

Phase 2

KCT built upon the success of the 2009 project with Phase 2 in 2014. We constructed 8 main-stem large and 2 side-channel wood structures (engineered log jams or ELJs), placed 30 anchored tree snags in the main river channel and 30 individual unanchored snags in side channels, excavated 4 side-channel inlets, and constructed 4 gravel bars. A total of 5 miles of side-channel habitat and 240 acres of floodplain were reconnected to the Cle Elum River.

This project used a helicopter to build the large wood structures making it the first of its kind. All but one of the large wood structures and all 30 anchored snags were constructed using a Vertol 107 helicopter, which allowed us to stay out of critical wetland areas leaving them intact and healthy. Previously, restoration projects used large machinery such as dozers, excavators and side dumps to complete the project. Although the vegetation grows back over time, the short-term consequences are that it disrupts vegetation and can introduce invasive species. We were able to avoid all that by using the helicopter.