Westchester Lagoon Channel – Reconnecting Fish from Cook Inlet to Chester Creek - Bob Butera , HDR (co-authors: Dan Billman/HDR)

ABSTRACT

Chester Creek flows through the Municipality of Anchorage from the Chugach Mountains to Cook Inlet. Historic and anecdotal data indicate it once had runs of four salmon species. Urban development impacted those runs, especially with the construction of the Westchester Lagoon dam in 1972. This structure impounded the lagoon system at the mouth of Chester Creek by flooding the intertidal estuary area. The dam spillway did contain a fish ladder but the ladder was not effective and restricted the ability of returning salmon to pass between Cook Inlet and the creek. Runs dwindled to less than 100 salmon. The spillway also restricted flood flows and elevated the flooding risk to lower Chester Creek. Beginning in 1987 the Municipality of Anchorage (MOA) began a process of addressing the fish passage with the first comprehensive evaluation to improve the fish ladder and lower channel. This presentation will cover the history of these efforts and how they evolved into the channel that MOA constructed in 2009. This history offers insight into the process of planning and designing this project over a 22 year period to meet technical, environmental, and social constraints, and how these changed over time. The final design will be presented in detail and will show how design features were selected to meet the physical forces, flood reduction, public use, and salmon migration needs. Finally, the talk will end with a discussion of the construction, its results, and feedback of the community. The project did meet its goal of improving fish passage with over 2,000 salmon representing all 5 species passing through the new channel into the creek system in 2009.

Topic: Fish habitat