The Contra Costa County Flood Control and Water Conservation District (CCFCWCD) received a grant of $1,250,000 from the Climate Adaption and Resiliency Program to restore 400 acres of coastal wetlands and adjacent habitat at the mouth of Walnut Creek and its tributary, Pacheco Creek.
The 150 square mile area of Lower Walnut Creek is the largest watershed in Contra Costa County and one of the largest in the Bay Area. The mouth of this creek system once supported expansive tidal marsh habitat, but over time grazing, farming, industrialization, and urbanization had degraded this habitat.
In the 1960s, the U.S. Army Corps of Engineers constructed levees along the creek banks and deepened the channel to control periodic flooding. However, sediment built up in the creek at higher rates than expected. By the early 1990s, an operation was planned to remove this sediment, as conditions existed to create a management dilemma that exists to this day: either the sediment is removed and habitat destroyed, or the sediment remains at the expense of flood capacity.
In response, the CCFCWCD, local communities, and partner organizations developed a vision to restore Lower Walnut Creek into a sustainable system with multiple and complementary objectives. It also accommodates for a range of future sea level rise scenarios. Since 2014, the CCFCWCD and partner organizations have been working to complete the planning, design, and permitting needed to implement this vision.
This project funds the excavation and grading needed to remove or relocate about two miles of dikes and levees to re-establish tidal connectivity and adjacent terrestrial habitats. The design allows wetland habitat to adapt to a rising sea level and will provide public access and recreation by connecting into two regional trails (Iron Horse and SF Bay Trail) that currently do not have access to the Suisun Bay.
Project Manager Paul Detjens of the CCFCWCD believes the effort it takes to create a resilient habitat is worth it: “It would be easier to design for maximum wetland benefits now, but instead we’re considering the longer view, and incorporating climate resiliency into the project. This provides great benefits now, but also ensures those benefits persist in the long term.”