Calabazas/San Tomas Aquino Creek-Marsh Connection Project
Pond A8 Complex, Alviso, northern San Jose, Santa Clara County (Exhibit 1); Measure AA Region: South Bay
Planning, data collection and analysis, develop design plans, prepare environmental documentation
Safe, Clean Water and Pollution Prevention Program; Vital Fish, Bird and Wildlife Habitat Program; Integrated Flood Protection Program; Shoreline Public Access Program
Valley Water, State Coastal Conservancy, US Fish and Wildlife Service
2023 UPDATE: The project team completed a draft conceptual alternatives report that details restoration design options. A monitoring plan was completed that will direct the collection of baseline data that will be used to evaluate the project and inform future adaptive management actions.
The project will restore natural connections between the watershed and San Francisco Bay. Restoration of natural processes, such as the deposit of marsh-sustaining sediment, will support the development of tidal marsh in a group of former salt production ponds (Ponds A8, A8S, A5, and A7, referred to as the Pond A8 Complex), as well as riparian habitat and freshwater marsh. The project will also restore and enhance wildlife habitat, reduce flood risk for the surrounding community, and fill a gap in the Bay Trail.
Valley Water has already completed its internal Feasibility Report for this project and is ready to proceed with further project planning. During this planning phase, Valley Water will further develop the problem definition, data collection, and stakeholder outreach, as well as an analysis of a range of project alternatives that accomplish the project’s goals. The planning phase typically includes preparation of 30% design plans to support alternatives analysis and CEQA/NEPA document preparation. At the conclusion of the planning phase, the project, with well-defined major components, will be approved by the Valley Water Board and will move forward into detailed design.
The funding will provide critical support to Valley Water for planning and early design of the proposed project. The Calabazas-STA Project fulfills one of the goals of the South Bay Salt Pond (SBSP) Restoration Project, a multiagency effort to restore over 15,000 acres of former salt evaporation ponds in South San Francisco Bay. The long-term goal of the SBSP Restoration Project is to fully open the 1440-acre Pond A8 Complex to unrestricted tidal flows to facilitate marsh restoration. In 2010, during Phase I of the SBSP Restoration Project, Pond A8 was connected to the Bay via water control structures on Alviso and Guadalupe Sloughs. These reconnections have created a muted tidal system that allows tidal waters to enter the pond, but since the land has subsided, it does not fully drain during low tide. Additional reconnections are necessary to fully restore tidal influence and sediment input to the complex and allow for the establishment of tidal marsh.
This project will fund planning, data collection and analysis, early design, and the environmental clearance process for the Calabazas-STA Project. Baseline monitoring and scientific studies will support planning efforts, environmental clearance, and design, as they will provide the data necessary to understand sediment transport and supply from Calabazas and STA creeks, identify potential project impacts to fish and other wildlife and water quality, including potential impacts from resuspension of sediment contaminated with mercury, as well as give detailed bathymetric and topographic information that will inform hydrodynamic and sediment transport modeling and the design process.