Res21 16010 final - Laserfiche WebLink

Browse Search

2021 Multijurisdictional Local Hazard Mitigation Plan Rocky Intertidal Habitat Rocky intertidal habitat, such as that at the Fitzgerald Marine Reserve, is identified in Climate Change Vulnerability Assessment for the North-Central California Coast and Ocean as moderately sensitive to sea level rise. The habitat is also affected by hard armoring of the coastline and roads that prevent inland migration of beaches. These sensitivities are compounded by other natural and human-related factors, including temperature, invasive species, pH, and pollution (County of San Mateo, 2018). Wetlands Wetlands are an important natural asset in the County. They protect the shoreline from flooding and erosion from storms, and they are an important recreational and educational resource to the community. Wetlands contribute to a community’s resilience to flooding by providing a storm surge buffer, erosion control, water -quality maintenance, and fish and wildlife habitat. Wetlands are not very sensitive to temporary inundation, but they are more sensitive to permanent inundation from sea level rise, which could permanently convert them to tidal mudflat. However, wetlands may be able to build up sediment, or accrete at a pace equal to sea level rise (reflective of their adaptive capacity), which would prevent their permanent loss. This accretion would depend on an adequate supply of sediment, the extent to which the shoreline is developed, and how quickly the water level rises. These conditions are affected by human and natural processes upstream of San Francisco Bay and by coastal shoreline management practices on the Coastside. For example, coastline hardening or infrastructure (such as a jetty) in one place can exacerbate erosion elsewhere. In total, over 7,000 acres of wetlands (more than 80 percent of all wetlands assessed in the project area) could be lost to temporary or permanent flooding or erosion. This area includes the Pillar Point Marsh, Bair Island, and the Ravenswood Pond Complex (County of San Mateo, 2018). Wetlands also provide flood protection benefits, and sea level rise could lead to a reduction in those benefits as wetlands become converted to mudflats with rising water levels (Hayden et al., 2019). 13.5 FUTURE TRENDS IN DEVELOPMENT The overall land area of San Mateo County will decrease as sea level rise permanently inundates the County’s lowest areas. This will have significant impacts on land use and planning in local communities. Local general plans as well as climate action/adaptation plans in the planning area will guide this future development. State mandates have sought to strengthen land use application in areas impacted by sea level rise. Local general plans should be referenced and cross-referenced with the results of this plan to mitigate future development in areas most vulnerable to sea level rise. California legislation (such as AB-32,AB-2800, SB-97 and SB-379, described in Chapter 6) equips local governments with planning tools to address sea level rise impacts as future development pressures interface with the sea-level rise hazard areas. 13.6 SCENARIO Sea levels along the San Mateo County coast will rise over the next 80 years and beyond, and the county and coastal and Bay facing cities will be adversely impacted by that rise. The impacts are already happening and will 13-10