South Bay Salt Pond Restoration Project
The South Bay Salt Pond (SBSP) Restoration Project is the largest tidal restoration project on the West Coast, and will transform 15,100 acres to a mosaic of tidal wetlands and managed pond habitats. In addition, the restored tidal wetland system will provide a critical natural buffer against the effects of climate change such as sea level rise, coastal flooding, and erosion.
Salt production has occurred in San Francisco Bay since the 1800s, and a large percentage of wetland loss in the south bay was due to tidal lands levied for salt ponds. In 2003, under the leadership of Senator Dianne Feinstein, Cargill, Inc. sold back approximately 16,500 acres of salt ponds (15,100 acres in South Bay and 1,400 acres in North Bay) to the State of California. Federal and state resource agencies and several private foundations provided funding for the purchase. Following the salt pond acquisition, the Center for Collaborative Policy began working with the US Fish and Wildlife Service (USFWS), the California Department of Fish and Game (CDFG), and the California Coastal Conservancy (CCC) to design a restoration plan. The final SBSP Restoration Plan was adopted in 2008 with the primary goal of restoring and enhancing the wetlands to historic tidal marsh conditions, and providing wildlife habitat, recreational opportunities, flood protection, and water quality improvement.
The six project objectives of the SBSP Restoration Plan include:
- Create, restore, or enhance habitats;
- Maintain or improve existing levels of flood protection;
- Provide public access and recreational opportunities;
- Protect or improve existing levels of water and sediment quality;
- Implement measures to improve current levels of vector management and manage the spread of invasive species; and
- Protect the services provided by existing infrastructure.
The SBSP Restoration Project evaluated three long-term alternatives to restoring salt ponds in South San Francisco Bay: (A) no action; (B) managed pond emphasis (50:50 tidal habitat : managed ponds by area); and (C) tidal emphasis (90:10 tidal habitat : managed ponds by area). Alternative B, when fully implemented, would provide approximately 7,500 acres of tidal habitat and 7,500 acres of managed salt pond habitat. Alternative B designates approximately 20% of the managed pond habitat to be intensely managed for birds (e.g., waterfowl, shorebirds), provides a cohesive line of flood protection along the landward edge of the former salt ponds, and provides public access and recreation features. Alternative C, when fully implemented, would provide approximately 13,400 acres of tidal habitat and 1,600 acres of managed salt ponds. Alternative C designates all managed pond habitat to be intensely managed for birds, and provides similar flood protection and recreation features to Alternative B. Because the optimal configuration of tidal habitat and managed salt ponds that achieves project objectives while avoiding adverse impacts to ecosystem services and/or resources cannot yet be determined due to several uncertainties, it was decided to implement an adaptive management plan.
The basic approach of the SBSP Adaptive Management Plan is to implement restoration efforts in multiple phases; lessons learned from each phase of the project will be used to inform future phases and determine the final habitat configuration. The final outcome is likely to fall between the 50:50 and 90:10 scenarios, and would achieve the maximum amount of tidal restoration possible without causing adverse affects on ecosystem services and/or resources.
Outcomes and Conclusions
Phase 1 of the SBSP Restoration Project began in 2008 with the goal of working towards the 50:50 scenario. For example, 53 water systems were installed throughout several ponds with the aim of slowly adding water back into the salt pond system and lowering the salinity before reintroducing the water into the bay. In addition, a large monitoring effort has begun to look at what bird species are regularly using the salt ponds in order to determine habitat use and needs. Finally, Phase 1 actions have been very targeted to provide immediate ecosystem services as well as to address key uncertainties (e.g., mercury contamination) surrounding the SBSP project, and are intended to help inform future phases. Phase 1 projects are expected to be completed by 2012. Detailed planning for Phase 2 will begin in 2011 (initial planning has already begun), with the final Phase 2 projects to be completed in the next 5-10 years.
Challenges that have arisen during the project include:
- Because the salt ponds have existed in San Francisco Bay for some time (i.e., 100-150 years), new suites of species have adapted to the high salinity and utilize the salt pond habitat. In addition, in some high salinity ponds they have observed a disproportionate number of certain avian species. Thus, restoration strategies were required to incorporate both habitats (i.e., salt ponds and tidal wetlands) rather than simply restoring all habitats to tidal wetlands.
- During the gold rush, South San Francisco Bay had one of the largest mercury mines, which led to dormant and isolated mercury contamination in the salt ponds. Restoration efforts such as restoring tidal action or permanent flooding could cause the mercury to be mobilized.
- Restoration of tidal wetlands will lead to new habitats that invasive species (e.g., non-native [and hybrid] Spartina) may colonize.
In addition to several of the challenges currently faced by the SBSP Restoration Project, sea level rise is predicted to impact sediment supply and accretion. Thus a main goal of restoration efforts is to act with a sense of urgency (i.e., building marshes back up as soon as possible), thereby increasing ecosystem resilience and keeping up with likely sea level rise. All of these challenges are being addressed through directed studies by teams of researchers as part of the adaptive management strategy.
Kershner, J. (2010). South Bay Salt Pond Restoration Project [Case study on a project of the California Coastal Conservancy]. Product of EcoAdapt's State of Adaptation Program. Retrieved from CAKE: www.cakex.org/case-studies/south-bay-salt-pond-restoration-project (Last updated February 2011)