Marsh Creek Reservoir Restoration and Total Mercury Reduction Project

The Marsh Creek Reservoir Restoration and Total Mercury Reduction Project, identified as Project No. WO8104 and CP#23-35, is a multi-benefit initiative managed by Contra Costa County in California. The project is designed to improve the flood capacity of the Marsh Creek Reservoir, enhance water quality, restore the local ecosystem, and increase the value of public recreation in the area. To achieve these goals, the scope of work includes the excavation of excess accumulated sediment and debris from the reservoir wet pool, the drying and onsite disposal of removed materials, and the creation of a high flow diversion. Additionally, the project involves habitat restoration, the installation of cattle exclusion fencing, and the cleaning, maintenance, and operation of the existing primary outfall gate. This project is conducted under the guidance of the California Environmental Quality Act, with the Board of Supervisors approving the project following the preparation of an Environmental Impact Report and a Mitigated Negative Declaration. The project is classified under NAICS code 562910 and is located in California zip code 94513. Administrative oversight is provided by the County Department of Conservation and Development, with key points of contact including Senior Planner Syd Sotoodeh and Environmental Analyst III Laura Cremin. A Notice of Determination was filed on August 10, 2026, confirming the adoption of mitigation measures and a monitoring plan to ensure environmental compliance.