The issues of salmon decline and rising flooding dangers are urgent and will intensify over time. That’s why the Chehalis Basin Strategy is putting solutions in place to protect people, fish, and wildlife now, while also planning for a more resilient future.

With support from its many partners, the Chehalis Basin Strategy is designing and implementing on-the-ground projects to restore aquatic habitats and protect residents from flood damage. The Strategy also includes planning for large-scale, long-term solutions so the Basin continues to be a wonderful place to live for generations to come.

Since 2012, state and local partners have invested nearly $100 million to fund more than 100 projects that benefit both people and aquatic life. After a decade of science-based research and collaboration to build a strong foundation, the number of Chehalis Basin Strategy  projects has ramped up significantly in recent years and will continue to grow.

Read about the history of the Chehalis Basin Strategy.

Why We Need a Flow Through Dam for Flood Control

This structure is needed to protect the Chehalis Basin community, especially those most vulnerable, from severe economic, social, and environmental consequences.

How It Works

The flow-through dam for flood control balances flood risk reduction with natural biological and physical riverine processes. This innovative structure is designed to reduce damage from major and catastrophic flooding.

Most of the time, the Chehalis River will move through the flow-through dam for flood control, allowing fish to pass upstream and downstream on their own. During major floods, the flow-through dam will store water in a temporary reservoir and slowly release it back to the river as conditions return to normal. There will be no permanent storage of water, so in non-flood times, the river and its fish would move naturally through fish passage conduits in the facility.

Design Updates

In 2020, the Washington State Department of Ecology and the U.S. Army Corps of Engineers released their respective Draft Environmental Impact Statements (DEISs), which described potential impacts on environmental resources from the construction and operation of the flow-through dam for flood control. 

To address the findings described in the DEISs, the flow-through dam for flood control has undergone considerable design revisions, and the mitigation plan has been enhanced to provide a robust suite of actions that target multiple natural resources.