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Sherman Island 600 Acre Wetland Restoration To Improve Water Quality

Rio Vista, CA

Creation of 650 acres of permanent managed wetland units with earthen compacted berms. An existing scour pond was filled in with fill material. Great Lakes E&I also constructed an aggregate base road, installed water control structures, excavated a ditch around the new area, and planted new native vegetation.

Topics Covered

Coastal & Tidal Flooding
Hurricanes & Severe Storms
Sea Level Rise
Stormwater Management

Cost

Initial: 5.3 Million USD

Funding

General Fund/Existing Public Funds

Grants

State and local grants

Project Status

Operational since 2016

Gov Champion

California Department of Water Resources

Problem Addressed

As critical habitat and part of California's water management system, Sherman Island was prioritized for restoration.

The goals of the effort were to reverse subsidence on a section of this low-lying Sherman Island by permanently flooding it, while also improving the habitat available to wildlife occurring in the area. The project would also increase stability and reduce seepage on a threatened section of the levee. Finally, as the first of a two part effort, this 650-acre project would help determine key project impacts including the rates/amounts of carbon sequestered, the air and water quality impacts, and provide a basis for potential Delta-wide implementation.

Solutions Used

Due to the groundwater table being just below the existing ground surface, dewatering channels, sumps, and pumps were strategically constructed throughout the 650 acre site.

The project also utilized low ground pressure equipment to excavate the swales and ponds and to shape earthen berms. Because the characteristics of the existing soil were a highly saturated peat material, the balance of the excavation to fill was difficult to design and construct in a cost and time effective manner. Together, the local government engineer and Great Lakes worked together to adjust the design excavation swales to create manageable/cost-effective hauls and to stay within the design plan so the final product would still function properly. The construction schedule was designed so that certain areas would be completed, to allow the existing habitats to move into the new areas while construction progressed. The project was monitored by an external team to minimize the impact on all existing plants and animals found within in the construction limits.

Outcomes

1

Improving the habitat available to wildlife occurring in the area.

2

Increased stability and reduced seepage on a threatened section of levee.

3

Reduction of water diversion from agricultural practices, resulting in increased waterfowl breeding and loafing habitat.

4

Contributes to the total project GHG sequestration of approximately 20,000 metric tons CO2-eq per year.

Something Unique

Completed in one season to limit disruption to the wildlife.

Last Updated

May 3rd, 2018
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