New Dams Proposed for Chehalis River (WA)
This spring Lewis County PUD released a Draft Study Report for Chehalis River Water Retention
Facilities. If implemented, the plan calls for the construction of two dams including a 220 foot
high and 1960 foot wide dam on the mainstem of the Chehalis River and another slightly smaller
dam on the South Fork Chehalis. The primary purpose of the dams would be flood control but they
would also be constructed to generate hydropower. Earlier today the PUD hosted a scoping meeting
attended by members of the public, agency staff, tribal representatives, and American Whitewater
to further discuss the proposal and solicit information on data gaps.
These dams would inundate an outstanding class III whitewater run, one of the longer stretches of continuous whitewater in the state, and our preliminary analysis indicates they would inundate or block access to at least 40 miles of high quality salmonid habitat. The proposal for these dams is in response to flooding that has occurred in the Chehalis River Valley that in recent years has resulted in closures of Interstate 5. The most significant event was in 2007 when 20 inches of rain fell in a 500 year event. While the flooding has resulted in significant regional economic impact, we believe there needs to be a broader evaluation of responses that include an honest assessment of current and future land use and potential locally-based flood control measures that protect critical infrastructure without massive water development projects.
The proposed study report contends that fishery resources will benefit from increased water storage that can be released in low-water summer months. Our experience on other projects in the region has been that these benefits are typically not realized in practice and the loss of habitat connectivity, access to critical spawning habitat, loss of spawning gravel transport, channel incision in a sediment-starved regulated river, and disruption of key elements of naturally occurring process flows all combine to seriously question our ability to improve a river by building a dam and instituting a regulated flow regime.
American Whitewater will continue to track this project and monitor opportunities for the public to provide input.
- Chehalis River Water Retention Facilities Potential Study, Draft Report
Report from EES Consulting for Lewis County PUD on proposed dam for the Chehalis River.
American Whitewater is committed to the stewardship and conservation of the Chehalis River where a new dam is proposed.