Dam Goes Green: Protecting Fish and Homes

Completed in 1948, Washington State's Mud Mountain Dam has long protected downstream communities from flooding. Initially, its fish passage system, a trap-and-haul design, moved approximately 20,000 fish annually. However, this system proved insufficient for increasing salmon runs and protecting endangered species like Puget Sound Chinook salmon.

In response, a significant ecological infrastructure project was undertaken. Awarded in March 2018, a $112 million contract initiated the construction of the nation's largest trap-and-haul fish passage facility. This new system, completed around December 2020, can transport up to 60,000 fish per day, accommodating up to 1.2 million annually during peak pink salmon runs.

The upgrade involved extensive collaboration, including over 150 employees from multiple US Army Corps districts and input from various tribal and state agencies. The modernized dam now balances its crucial flood-control role, safeguarding over 400,000 homes and businesses, with enhanced environmental management, ensuring fish migration while maintaining community safety for decades to come.