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Proceedings of Coastal Zone 07 Portland, Oregon July 22 to 26, 2007

PLANNING FOR SEA LEVEL RISE IN SAN FRANCISCO BAY

Leslie D. Lacko, San Francisco Bay Conservation and Development Commission Keywords: sea level rise, climate change, climate adaptation, San Francisco Bay, estuary, regional planning, collaborative process INTRODUCTION The San Francisco Bay Area has a vibrant regional economy that is centered on its defining feature, San Francisco Bay. The Bay shoreline is heavily developed with business, residential, industrial and port facilities as well as major transportation corridors. At the same time, the Bay supports vast recreational activities and tidal marsh habitat. Much of the vital infrastructure, natural resources, and shoreline development are at risk from accelerated sea level rise due to climate change. The San Francisco Bay Conservation and Development Commission (BCDC) has been highly effective in achieving its primary public policy goal, to end rampant filling of San Francisco Bay that reduced the size of the Bay by about a third (the Bay is now 12.5 square miles larger than it was when BCDC was created). This narrow mandate at the heart of BCDC's Coastal Management Program leaves the agency unequipped to address sea level rise. Therefore, in its 2006-2011 Assessment and Strategy, BCDC identified the need for an update to the policies in BCDC's primary policy guidance document, the San Francisco Bay Plan. It further identified the need for a collaborative planning process that involves local jurisdictions and other regional agencies facing similar constraints. In cooperation with other Bay Area regional agencies, BCDC is now engaged in a process to plan for sea level rise through public outreach, coordinating with local jurisdictions, identifying regional adaptation strategies, and developing new San Francisco Bay Plan policies. BACKGROUND Long-duration tide gauges indicate that sea level in the San Francisco Bay estuary has risen 7.6 inches over the past 150 years, increasing at an average annual rate of 0.04 to 0.08 inches per year, which is consistent with global sea level rise (California Energy Commission, 2003). As global temperatures rise, evidence suggests that the rate of sea level rise will increase. The California Climate Change Center estimates that mean sea level will rise between 4 and 35 inches by 2100 (California Environmental Protection Agency, 2006). The impacts of relative sea level rise in the Bay could be more extreme in the southern and northern reaches of the Bay where land has subsided to below mean sea level (BCDC, 1988). It is expected that the occurrence of extreme events will increase as sea level rises. Recent modeling of sea level rise and changes in air and water temperature indicate that an 11.8-inch increase in sea level rise "would shift the 100-year storm surge-induced flood event to once every 10 years," (California Climate Change Center 2006). Tidal flooding associated with increased sea level and storm activity is expected to impede drainage in low-lying shoreline areas of the Bay and inundate developed waterfronts.

Proceedings of Coastal Zone 07 Portland, Oregon July 22 to 26, 2007

In addition to shoreline inundation from a rising Bay and flooding from increased storm activity, reduced timing of fresh water inflow to the Bay coupled with a rise in sea level could alter the estuarine ecosystem by: (1) increasing salinity in the northern reaches of the Bay and the Suisun Marsh, thereby reducing the extent of brackish marsh in the Suisun Marsh (CalEPA, 2006); (2) altering species composition (Galbraith et al., 2002, 2003; Stralberg et al, 2004); and (3) disrupting sediment delivery as well as the balance between accretion and erosion (Orr et. Al 2003), thereby affecting the success of over 30,000 acres of tidal marsh restoration currently underway. METHODS AND PROCESS The primary objectives of the sea level rise planning process are to: (1) analyze existing information on the Bay-related impacts of climate change, identify information needs, and provide a summary report; (2) engage the public in the planning process though an initial public outreach effort; (4) identify adaptation strategies; and (5) update the pertinent policies of the San Francisco Bay Plan. The first step in the process was to identify existing efforts to address climate change and form partnerships. This step led to a regional climate protection campaign coordinated through the Joint Policy Committee (JPC). The JPC is made up of four regional agencies, including BCDC, the Association of Bay Area Governments, the Bay Area Air Quality Management District, and the Metropolitan Transportation Commission. Through the analysis of existing information on the Bay-related impacts of climate change, primary management issues and additional information needs were identified. Through a local government break-out session at a region-wide Climate Protection Summit hosted by the Bay Area Air Quality Management District, local jurisdictions identified their issues and needs. Following up the needs and issues identification that came out of the Summit and building on a statewide survey of coastal managers by Susanne Moser of the National Center for Atmospheric Research, a targeted set of structured interviews was conducted to further refine a list of issues and information needs of local jurisdictions. Information from Moser's survey and BCDC's interviews identified the following needs of local jurisdictions: (a) greater coordination both regionally and statewide; (b) centralized information access, such as a climate information clearinghouse; (c) public outreach; (d) vulnerability assessments; (e) guides for implementation, such as sample ordinances or user manuals; and (f) hands on training. RESULTS AND NEXT STEPS The needs "c" and "d" above were met by mapping a sea level rise scenario and providing the maps as an initial vulnerability assessment and public outreach tool along with some basic information about the impacts of sea level rise. Geographic information system software was used with a digital surface model of the San Francisco Bay and shoreline to create illustrative maps of low lying shoreline areas that would be at risk of flooding with a one meter rise in sea level (Figures 1 and 2). The need for greater coordination is being addressed through the efforts of the JPC, which has developed a coordinated, systematic response to climate protection that includes BCDC's sea level rise planning process. Future steps in the sea level rise planning process include: (1)

Proceedings of Coastal Zone 07 Portland, Oregon July 22 to 26, 2007

updating the sea level rise maps as more sophisticated information becomes available and disseminating them to local jurisdictions; (2) identifying regional strategies to adapt to sea level rise; and (3) updating the policies of the San Francisco Bay Plan.

Figure 1. Sample Sea Level Rise Map of San Francisco Bay

Proceedings of Coastal Zone 07 Portland, Oregon July 22 to 26, 2007

Proceedings of Coastal Zone 07 Portland, Oregon July 22 to 26, 2007

Figure 2. Sample Sea Level Rise Map of San Francisco International Airport

Proceedings of Coastal Zone 07 Portland, Oregon July 22 to 26, 2007

LITERATURE CITED California Climate Change Center (2006). Projecting Future Sea Level. publication # CEC-500-2005-202-SF. March. Sacramento. California Energy Commission. 2003. Climate Change and California. Staff Report 10003-017F. Sacramento. November. California Environmental Protection Agency (2006). Climate Action Team Report to Governor Schwarzeneggar and the Legislature. March. Sacramento. Galbraith, H., R. Jones, R. Park, J. Clough, S. Herrod-Julius, B. Harrington, and G. Page. 2002. Global Climate Change and Sea Level Rise: Potential Losses of Intertidal Habitat for Shorelibirds. Waterbirds. 25(2):173-183. Orr, M., S. Crooks, and P.B. Williams. 2003. Will Restored Tidal Marshes be Sustainable? San Francisco Estuary and Watershed Science 1(1):Article 5. Stralberg, D., V. Toniolo, G.W. Page, and L.E. Stenzel. 2004. Potential Impacts of NonNative Spartina Spread on Shorelind Populations in South San Francisco Bay. PRBO Report to California Coastal Conservancy (contract #02-212). PRBO Conservation Science, Stinson Beach, CA.

Leslie D. Lacko San Francisco Bay Conservation and Development Commission 50 California Street, Suite 2600 San Francisco, CA 94111 Phone: (415) 352-3646 E-mail: [email protected]

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