RIVERSIDE, Calif. — Local and federal agencies are working together to restore a critical stretch of flood control infrastructure protecting thousands of homes and billions of dollars in property and infrastructure in Riverside.

Led by the U.S. Army Corps of Engineers Los Angeles District, in partnership with the Riverside County Flood Control and Water Conservation District, the project is rehabilitating damaged portions of the Riverside levees — two parallel levees originally built in the 1950s to channel floodwaters safely through urban areas. Known formally as Riverside Levee 1 (west levee) and Riverside Levee 2 (east levee), the structures are part of the larger Santa Ana River levee system.

According to the Riverside County Flood Control and Water Conservation District, about 9,000 feet of the west levee will be rehabilitated, stretching from Market Street to just past Capary Road. Meanwhile, about 4,000 feet of the east levee will be restored from the county line to near Columbia Avenue, with additional work planned between Market Street and State Route 60.

The repairs involve reinforcing and extending the existing rock slope protection to address areas where erosion has gradually worn down the levee, ensuring long-term stability and continued protection. Much of the observed damage stems from storms in late 2010 and early 2011, which brought substantial flows through the Santa Ana River and caused erosion to the riverbanks, including damage to several groins, which are rock structures designed to slow water and reduce impact on the levee slopes.

“These storm events resulted in some scour to both the right and left levees,” said Brandon Colvin, project manager with the LA District. “The U.S. Army Corps of Engineers went out to the site to do some investigations and identified the areas of concern. A project information report was generated to assess the specific areas that needed to be corrected and what type of design would be used as the best mechanism to make those repairs.”

In addition to restoring eroded areas, the project includes innovative features, such as the addition of “launchable stones” for dynamic scour protection. The stones are designed to activate during extreme storm events, providing levee protection when traditional revetments are not always viable.

“During a big storm event, these stones can ‘launch’ and fall into the scour position to act as a revetment from that storm,” said Jung Lee, civil engineer for the project. “These stones are designed to provide an effective means of levee scour protection when we can’t place these revetments underground for various reasons, like in our case, where we couldn’t excavate down below the groundwater.”

The levees range in height from 15 to 22 feet and were originally designed to carry flows of up to 195,000 cubic feet per second — well above the 100-year flood estimate of 140,000 cubic feet per second. Their performance is critical to protecting more than 4,300 structures in the Riverside and Jurupa Valley areas, including more than 4,000 homes and about $1.5 billion in infrastructure.

Colvin emphasized that USACE is working closely with local agencies, including the Riverside County Flood Control and Water Conservation District, to ensure all necessary repairs are made to the levees. He noted that the project is federally funded under Public Law 84-99, which allows USACE to assist in the repair of both federal and nonfederal flood protection projects damaged by storms.

Colvin also highlighted the extensive coordination involved in the project, particularly in terms of environmental mitigation. The project includes robust environmental monitoring, he said, with a firm on-site daily to ensure best management practices are being followed and seasonal surveys of bird habitats and fish populations are conducted to minimize impacts on local ecosystems.

“There’s been extensive coordination with other resource agencies — local, state and federal — through the life of the project, especially in the design leading up to the award of the contracting construction,” he said. “The contractor is currently working on the right levee. They’ve made some good progress there and are starting to make some of the repairs both to the rock, as well as getting the grouted portions placed.”

Colvin praised the collaboration with Riverside County, noting the project has received significant support at all levels of USACE.

“This project represents a significant amount of coordination with Riverside County,” Colvin said. “They’ve been amazing partners to work with here. This project has really been at the forefront, not only of the Los Angeles District, but also the South Pacific Division and even at Headquarters USACE, where there’s been a significant amount of support thus far. The success and continuation of the project is a direct product of that collaboration and that support at all levels of the organization.”

Construction is ongoing and will continue in phases as weather and site conditions allow. According to Colvin, work on the right levee is expected to be completed by the summer of 2026, followed by a one-year establishment period to ensure the longevity of the levee’s structural integrity. The left levee is forecasted to begin construction in the fall of 2025.

“We have high confidence that the resulting project will provide a long-term solution to the community,” Colvin added. “If we think back to the original construction, which was in the late 1950s, that was intact for 50-plus years with minimal impact. We fully expect this project will continue for many decades to come.”