PWA - Project - Napa River Salt Marsh

Restoration of the Napa River Salt Marsh system has long been a high priority for local resource agencies and the environmental community. The conversion of approximately 10,000 acres of former salt production ponds to tidal and pond habitats is ecologically important to San Francisco Bay. It will provide habitat to endangered species, migratory waterfowl, shorebirds and anadromous and resident fish. The multi-year restoration effort is significantly larger than others in San Francisco Bay and one of the largest on the west coast of the United States.

PWA worked in cooperation with the US Army Corps of Engineers, California Coastal Conservancy, California Department of Fish and Game and other resource agencies and universities to provide hydrology, geomorphology and restoration design services. The team undertook three major tasks:

PWA characterized existing site conditions and assisted in identifying and scoping key data collection needs to balance information needs and available budget. The team executed key components of the collection effort to assess opportunities and constraints for restoration. Specific efforts included field studies, the development of sampling methods suitable for use in the highly saline ponds and water quality analysis.

PWA developed and calibrated a hydrodynamic model of salt transport within the 11-pond system and northern San Francisco Bay. This model was used to help the client identify options for lowering pond salinities to levels optimal for creating ponded habitat and acceptable for restoration breaching. PWA estimated the required flow of supplemental fresh water, effects of effluent discharge into the receiving water and time required to meet salinity targets.

Preliminary restoration design alternatives were developed based on geomorphic principles, hydrodynamic modeling and sediment transport analysis. Design development included defining restoration design components, evaluating potential impacts and mitigation approaches and estimating habitat evolution.

<< Return to project summaries
Title		Napa Sonoma Marsh Restoration (PDF) 80kb
Project Summary		PWA provided hydrology, geomorphology and restoration design services for 10,000 acres of former salt production ponds.
Date		1996–present
Location		Napa County, CA
Client		California State Coastal Conservancy and US Army Corps of Engineers

Project Detail		Restoration of the Napa River Salt Marsh system has long been a high priority for local resource agencies and the environmental community. The conversion of approximately 10,000 acres of former salt production ponds to tidal and pond habitats is ecologically important to San Francisco Bay. It will provide habitat to endangered species, migratory waterfowl, shorebirds and anadromous and resident fish. The multi-year restoration effort is significantly larger than others in San Francisco Bay and one of the largest on the west coast of the United States. PWA worked in cooperation with the US Army Corps of Engineers, California Coastal Conservancy, California Department of Fish and Game and other resource agencies and universities to provide hydrology, geomorphology and restoration design services. The team undertook three major tasks: Assessment of Opportunities and Constraints PWA characterized existing site conditions and assisted in identifying and scoping key data collection needs to balance information needs and available budget. The team executed key components of the collection effort to assess opportunities and constraints for restoration. Specific efforts included field studies, the development of sampling methods suitable for use in the highly saline ponds and water quality analysis. Modeling of Interim Management for Salinity Reduction PWA developed and calibrated a hydrodynamic model of salt transport within the 11-pond system and northern San Francisco Bay. This model was used to help the client identify options for lowering pond salinities to levels optimal for creating ponded habitat and acceptable for restoration breaching. PWA estimated the required flow of supplemental fresh water, effects of effluent discharge into the receiving water and time required to meet salinity targets. Tidal Wetland Restoration Design Preliminary restoration design alternatives were developed based on geomorphic principles, hydrodynamic modeling and sediment transport analysis. Design development included defining restoration design components, evaluating potential impacts and mitigation approaches and estimating habitat evolution.