Southport Levee Improvement Project

Supporting Multi-Benefit Flood Protection Projects in California

Client

Location

Key Elements

GEI supported West Sacramento Area Flood Control Agency (WSAFCA) during construction and restoration of the Southport Levee Improvement Project, which provided flood protection for West Sacramento, California and created new floodplain habitat and recreational opportunities along the Sacramento River.

GEI archaeologists, biologists, and ecologists provided environmental compliance support and developed ecological restoration designs for this major multi-benefit flood risk reduction project. GEI provided biological and archaeological monitoring and cultural resources studies to support compliance with Federal and State permits during construction of 6.5 miles of levee improvements over 3 years. The coordinated efforts between WSAFCA, U.S. Army Corps of Engineers (USACE), Tribal representatives monitors, archaeological monitors, and the Principal Investigators fostered attentive and flexible response to inadvertent archaeological discoveries during the project.

GEI’s conscientious awareness of regulatory statutes, commitment to clear on-site management, and focus on open communication ensured that preservation protocol was followed by all project personnel. GEI archaeologists and restoration ecologists worked with WSAFCA and project engineers to redesign the project to avoid archaeological sites that were encountered during construction, ensuring that these significant cultural resources would be integrated with the ecological restoration design and preserved for future generations.

The project included construction of 4 miles of new setback levee along the Sacramento River. The old levee was breached in three locations, creating 120 acres of new floodplain habitat connected to the river. GEI led the ecological restoration planning and design process, including preparation of construction documents (i.e., plans and specifications) for restoration of the newly created floodplain. GEI worked with project partners to determine floodplain elevations that support desired habitats to benefit target aquatic species, including threatened and endangered salmonids and Delta smelt.

GEI developed a planting plan to create mixed riparian woodlands, mixed riparian scrub, riparian cottonwood forest, emergent marsh, tule marsh, and open water habitats on the site. GEI oversaw restoration of the site and worked with WSAFCA and USACE to secure advance mitigation credit for the newly created habitat to support future flood improvement projects.

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miles of levee improvements

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years working on the project

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acres of new floodplain created