The U.S. Army Corps of Engineers Sacramento District recently reached two important milestones for the small town of Hamilton City, California, a small agricultural community located about 100 miles north of Sacramento. Home to just under 2,000 people, the history of Hamilton City includes many flooding events and several near misses. The city and surrounding area were inundated in 1974, and its residents have been evacuated several times throughout the years during periods of extensive flood fighting including 1983, 1986, 1995, 1997, and 1998.
One of the primary reasons for this susceptibility to flooding has been the town’s reliance on a substandard and undersized levee called the “J levee” – a levee that does not meet any USACE engineering standards. And with the Sacramento River pressing relentlessly against the town’s Eastern boundary, winter storms can wreak havoc on the tiny embankment.
Margaret Engesser, a project manager with Sacramento District, has become very familiar with the Hamilton City and its levee system.
“December was an important month for the Hamilton City Flood Risk Reduction and Ecosystem Restoration project,” said Engesser. “It marked the completion of the construction of a portion of the new Phase 2B levee that will add additional protection for the town. Additionally, the first phase of the ecosystem restoration was completed.”
On December 17, Engesser joined Reclamation District 2140, California State Parks, and Larsen Wurzel & Associates to conduct a final levee inspection of just over a half-mile of the recently completed levee. The levee inspection was the final walk-through to ensure the work has been completed to the Corps’ required specifications.
The Hamilton City Project is unique because it is one of the Corps’ first multipurpose projects, authorized for the purposes of flood risk management and ecosystem restoration. When completed, it will include 6.8 miles of new “setback” levee, providing much-needed flood protection, and will restore approximately 1,500 acres of native riparian habitat.
“The plants in the first phase of the ecosystem restoration for the project have been growing for three years.” said Engesser. “This will help provide a more natural river function and the restoration work will benefit a variety of federal and state-listed species.”
Construction work on the project over the past year has included degrading the existing J levee, filling the gaps in the existing Phase 2A levee that was constructed in 2018, and placement of rip rap (heavy rocks) to protect the riverbank and the Highway 32 Bridge. By degrading the J levee, the new setback levee widens the channel and allows the river to reconnect to the natural floodplain.
Engesser said the completion of this new portion of the Phase 2B levee and the first phase of ecosystem restoration is a big accomplishment but added that there is still much more work to be done.
Over the next 1-2 years, a section of the Phase 2B levee still needs to be constructed. Once that has been completed, Hamilton City will be protected by an entirely new levee system that will provide much-improved flood risk management for its residents.
There is also a second phase of ecosystem restoration on the way, and like the first phase, it will take several years for the plants to fully grow and become established.
On top of these recent milestones, the Hamilton City Project was recently approved for $22 million in federal funding to complete the project and ensure that the full levee will be completed with all ecosystem restoration features established.
Read more about the Hamilton City Flood Risk Reduction and Ecosystem Restoration project: Sacramento District > Missions > Civil Works > Hamilton City (army.mil)