PWA - Project Detail - Bair Island

Bair Island, in South San Francisco Bay, once featured unspoiled tidal salt marsh, sloughs and mudflats. In the 1940s, the island was separated into three parts by levees to create commercial salt evaporation ponds. Local environmental groups have long regarded the restoration of Bair Island as a top priority to provide habitat for endangered species such as the California clapper rail and salt marsh harvest mouse. With restoration efforts now underway, Bair Island will become an integral part of the extensive wetlands within the US Fish and Wildlife Service’s Don Edwards San Francisco Bay National Wildlife Refuge.

The 1,500-acre site presented several opportunities for restoration: the remnant channels were still intact, the marshplain was only somewhat subsided and the adjacent existing marsh provided habitat connectivity. A straightforward restoration approach would have been to breach the islands in several perimeter locations and rely on estuarine sedimentation to raise site elevations over time. However, several constraints prevented the most direct restoration solution, including potential bird strike hazards at an adjacent airport; accelerated siltation in the adjacent Redwood Creek shipping channel; negative impacts to navigation in a local marina; and potential impacts to upstream creek flooding.

PWA’s analysis of the site and identification of critical issues allowed the client to address potential problems early in the design process and develop a feasible restoration alternative. The alternative solution provided intervention measures to minimize the constraints posed by adjacent site issues. Design recommendations included:

PWA’s services included field monitoring, geomorphic assessment, and hydrodynamic and sediment transport modeling. Efforts to provide probable costs of construction for various restoration alternatives were instrumental in the evaluation of the costs and benefits of the various design approaches, enabling the client to select and proceed with a cost effective approach to the restoration efforts.

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Title		Bair Island Salt Marsh Restoration (pdf) 1.21MB
Project Summary		Salt evaporation ponds have occupied Bair Island for the last 60 years. PWA is providing design and NEPA/CEQA compliance services to restore the site’s original tidal salt marsh, sloughs and mudflats.
Date		2000–present
Location		South San Francisco Bay, CA
Client		H.T. Harvey & Associates (for US Fish & Wildlife Service)

Project Detail		Bair Island, in South San Francisco Bay, once featured unspoiled tidal salt marsh, sloughs and mudflats. In the 1940s, the island was separated into three parts by levees to create commercial salt evaporation ponds. Local environmental groups have long regarded the restoration of Bair Island as a top priority to provide habitat for endangered species such as the California clapper rail and salt marsh harvest mouse. With restoration efforts now underway, Bair Island will become an integral part of the extensive wetlands within the US Fish and Wildlife Service’s Don Edwards San Francisco Bay National Wildlife Refuge. The 1,500-acre site presented several opportunities for restoration: the remnant channels were still intact, the marshplain was only somewhat subsided and the adjacent existing marsh provided habitat connectivity. A straightforward restoration approach would have been to breach the islands in several perimeter locations and rely on estuarine sedimentation to raise site elevations over time. However, several constraints prevented the most direct restoration solution, including potential bird strike hazards at an adjacent airport; accelerated siltation in the adjacent Redwood Creek shipping channel; negative impacts to navigation in a local marina; and potential impacts to upstream creek flooding. PWA’s analysis of the site and identification of critical issues allowed the client to address potential problems early in the design process and develop a feasible restoration alternative. The alternative solution provided intervention measures to minimize the constraints posed by adjacent site issues. Design recommendations included: Placement of dredged material fill on Inner Bair to accelerate marsh vegetation colonization and reduce bird strike hazards at the adjacent airport. Reestablishment of the historic channel meander to restore habitat and avoid impacts to the Redwood Creek shipping channel and local marina. Construction of a hydraulic control structure to prevent siltation of the Redwood Creek shipping channel. PWA’s services included field monitoring, geomorphic assessment, and hydrodynamic and sediment transport modeling. Efforts to provide probable costs of construction for various restoration alternatives were instrumental in the evaluation of the costs and benefits of the various design approaches, enabling the client to select and proceed with a cost effective approach to the restoration efforts.