Lake Sacajawea Flushing
Client—Longview, Washington
Lake Sacajawea was developed in 1924 when Fowler’s Slough was dredged, and the surrounding area was landscaped into a park. In the early 1950s, the City implemented a long-term maintenance plan for the lake and its surrounding park. Improvements included installing irrigation for landscaping and infrastructure to pump water from the Cowlitz River to “flush” the lake and enhance its water quality. After the City constructed a new water treatment facility in 2012, an alternative means of providing “flushing water” to Lake Sacajawea was needed.
Gibbs & Olson evaluated alternatives for supplying flushing water, which included identifying water sources for this purpose, developing design concepts and cost estimates for each alternative, addressing environmental and permitting issues associated with implementation, and recommending one alternative along with an implementation schedule.
The recommended alternatives were constructed in 2016, with Gibbs & Olson providing design and construction phase services for the improvements. The upgrades included enhancing the existing water intake structure on the Cowlitz River for use as a pump station. Four new submersible pumps were installed, each with a capacity of approximately 1,500 gpm, resulting in a total flow of 6,000 gpm. New slide gates were also installed, along with four new vertical-mounted fish screens.
Extensive permitting was required, including SEPA, Army Corps of Engineers, and a Section 106 cultural and historical resources review.
