New Floodgate Provides 200-Year Flood Risk Reduction

The Smith Canal Gate is a unique flood protection upgrade for the Stockton community. It’s part of the U.S. Army Corps of Engineers’ Lower San Joaquin River Project and supports California’s Statewide Plan for Flood Control. Designed and built by the San Joaquin Area Flood Control Agency (SJAFCA), it adds a new floodwall and gate on the San Joaquin River, connecting to an existing Federal Emergency Management Agency (FEMA)-accredited levee.

For many years, this area of central Stockton faced a higher risk of flooding. FEMA revoked the region’s levee accreditation in 2008, which placed about 5,000 properties and 15,000 residents in a Special Flood Hazard Area and required them to carry flood insurance. SJAFCA set out to restore that accreditation and meet California’s goal of providing at least a 200 year level of flood protection by 2025.

Isolating Smith Canal from the San Joaquin River during high water is key to reducing that risk. Once FEMA grants final approval, most homes in the area will no longer be mapped in the 100 year floodplain, and residents may no longer be required to buy flood insurance.

The new Smith Canal Gate is designed to stay open for everyday boat access to Atherton Cove and Smith Canal. It will close only during high water events or for periodic testing. The system helps the community meet modern state and federal flood protection standards. HDR has partnered with SJAFCA on this effort since 2008, providing engineering design and continued support through construction. The gate opened in October 2024 and will eventually connect to the larger $1.4 billion Lower San Joaquin River Project, which includes 23 miles of levee upgrades across north and central Stockton.

In January 2026, the gate was successfully tested and closed for the first time to help prevent flooding, an important milestone in securing long-term protection for the community.