Montezuma Tidal and Seasonal Wetlands Restoration Project
Montezuma Slough, Solano County, North Bay Region
Design; Maintenance; Monitoring; Construction/Implementation
Safe, Clean Water and Pollution Prevention Program; Vital Fish, Bird and Wildlife Habitat Program.
In February 2023, the Board of the Restoration Authority authorized a grant of up to $2,100,000 to Montezuma Wetlands LLC to place 300,000 cubic yards of dredged sediment that has been diverted from ocean disposal at the Montezuma Wetlands site in Suisun Marsh, Solano County, for the purpose of raising the elevation required for the Montezuma Wetlands Restoration Project, Phase 2. The project tasks in this phase will include negotiations with entities, mostly federal and local public entities, that are carrying out dredging projects that meet the project’s requirements for sediment quality and timing. It is estimated that the project will accelerate the wetland restoration and ecological benefits of over 1,100 acres of former salt marsh by raising the area closer to tidal marsh elevation prior to future tidal connections as part of the Phase 2 restoration.
The levee breach reconnecting the site to Bay waters occurred in October of 2020. The project area is now approximately 30% vegetated and supports a diverse mix of marsh plants. The newly restored marsh is supporting salt marsh harvest mice, western pond turtles, California least terns, and western snowy plovers, as well as many other native fish, shorebirds, and waterfowl. Small tidal channels are forming as expected and the water quality in the restored tidal marsh is similar to Montezuma Slough.
The project consists of tidal and seasonal wetland restoration on approximately 630 acres of currently diked baylands along Montezuma Slough and enhancement of adjacent uplands in Suisun Marsh.
The 630 acres of baylands will be restored to 566 acres of tidal marsh and subtidal habitat, 45 acres of seasonal wetlands, and 19 acres of high tide refuge and bird nesting habitat. Approximately 220 acres of adjacent uplands will be enhanced to improve upland habitat quality.
The project includes initial placement of dredged materials to raise the site elevation followed by additional construction activities and then breach of the existing dikes to enable tidal action on the site. Most of the dredged material has been placed. The authorization is to fund the other activities necessary to restore the site.
The project is located at a position in the San Francisco estuary where freshwater outflow from the Sacramento-San Joaquin Delta mixes with saline water from San Francisco Bay. Tidal marsh in this mixing zone supports high primary productivity that fuels the aquatic food web and provides food for many native fish species.