Marysville Ring Levee

The Yuba River Basin has experienced seven major floods since 1940, with catastrophic events in 1986 and 1997 causing damages of $95 million and $82.4 million, respectively. Despite past modifications to reduce flood risk, the City of Marysville remains vulnerable due to the region’s levee system. The Marysville Ring Levee (MRL) protects over 12,700 residents, 3,731 structures—including the region’s only level-3 trauma center at Rideout Memorial Hospital—and critical transportation infrastructure such as State Highways 70 and 20 and the Union Pacific Railroad. Without improvements, the levee system remains at risk of failure due to through- and under-seepage, threatening lives, property, and economic stability.

 

The Marysville Ring Levee project is a multi-phase effort to strengthen 7.6 miles of levee surrounding the city. The project includes constructing seepage cutoff walls and berms using open trench and deep soil mixing methods to meet the state’s 200-year urban flood risk requirement. The U.S. Army Corps of Engineers (USACE) Sacramento District is leading the project in partnership with the California Central Valley Flood Protection Board (CVFPB) and the Marysville Levee District (MLD). The estimated $92.5 million project is federally and state-funded, with California contributing $17 million as part of its broader levee system upgrades. Upon completion of each phase, USACE updates the levee’s Operations & Maintenance (O&M) Manual, and MLD assumes responsibility for ongoing maintenance.

 

The Marysville Ring Levee project has been progressing in multiple phases, with significant milestones completed, including:

• • Reach 1 and 3, Phase 1 – Open Trench Soil Bentonite Cutoff Wall (2014)
  • Reach 3, Phase 2A North – Open Trench Soil Bentonite Cutoff Wall (2018)
  • Reach 3, Phase 2A South – Deep Soil Mixing Soil Bentonite Cutoff Wall (2019)
  • Reach 3, Highway 70 Gap – Seepage Berm (2024)
  • Reach 3, Phase 2C – Deep Soil Mixing Soil Bentonite Cutoff Wall (2020)
  • Reach 3, Phase 3 – Deep Soil Mixing Soil Bentonite Cutoff Wall (Segment C) & Open Trench (Segments A&B) (2022)
  • Reach 3, Phase 4A – Seepage Berm (2017)

These upgrades have significantly enhanced the flood protection capabilities of Marysville, reducing risk and improving long-term resilience.

 

The project is nearing full completion, with the final construction efforts underway:

• • Reach 3, Phase 2B – Open Trench Soil Bentonite Cutoff Wall
    • 95% complete – Regraded back to full height, with ancillary work in progress

The project is expected to meet and exceed the flood protection criteria set by the state, making Marysville one of the safest urban areas in California’s Central Valley in terms of flood risk reduction.