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.
Thomas O'Keefe
3537 NE 87th St.
Seattle, WA 98115