Folsom Dam Raise

Folsom Dam sits on the Lower American River northeast of Sacramento. Because Sacramento sits at the confluence of the American and Sacramento rivers, it has been named one of the most at-risk cities for flooding in the United States of America. The need for increased flood risk management was realized after major storms impacted northern California in 1986 and 1997 causing record flood flows in the American River watershed. Outflows from Folsom Dam in addition to high flows in the Sacramento River exceeded the high safety margin of levees protecting the City of Sacramento. Had the storms lasted much longer, excessive water flow would have caused probable loss of human life and billions of dollars in damages. 

The Folsom Dam Raise Project consists of raising the elevation of Dikes 1 through 8, Mormon Island Auxiliary Dam (MIAD), Left Wing Dam, and Right Wing Dam by approximately 3.5 feet. This ensures these structures allow for operational flexibility and enhanced management of the enlarged flood storage capacity (in the form of surcharge). Additionally, the Main Dam’s Tainter gates will be modified enhancing the control of water flow.  

The Folsom Dam Raise has been progressing with significant milestones completed, including:  

• Dike 8 – raised 3.5 feet (2020)
• Dike