In 2015, the Marin County Community Development Agency (CDA) published a Vulnerability Assessment based on information from technical advisors, utility managers, and West Marin residents. The Assessment summarizes the expected timing and extent of impacts, laying a foundation of knowledge to guide adaptation planning.
Based on information from Marin County Community Development Agency (CDA).
General description
Marin County is located in the San Francisco Bay Area of the U.S. state of California. Marin’s coastline is stated to be vulnerable to sea level rise and changing storm patterns that accompany climate change. Over one-quarter of Marin County properties and natural and community assets are threatened by sea level rise along the coast.
The Marin County Community Development Agency together with different partners began in 2014 to develop a Vulnerability Assessment. The assessment presents asset profiles describing the vulnerability of parcels and buildings, transportation networks, utilities, working lands, natural resources, recreational activities, emergency services, and historic and archaeological resources; and community profiles highlighting vulnerable assets in different parts of the county. The findings are based on a combination of different sea level and storm scenarios representing near-term, medium-term, and long-term futures.
The Vulnerability Assessment is “advisory and not a regulatory or legal standard of review for actions that the Marin County government or CA Coastal Commission may take under the Coastal Act.” (CDA 2015: 4)
The Assessment is broken down in five different sections:
- Executive Summary and Introduction
- Asset Profiles
- Community Profiles
- Conclusion and Appendices
- Vulnerability Assessment Maps
Methodology
The Assessment methodology is based on the California Climate Adaptation Planning Guide (CA Emergency Management Agency, 2012). Based on this planning guide, five phases were undertaken (CDA 2015: 17):
- Phase 1| Exposure: Assess potential changes in water level from sea level rise, storm events, and geomorphic change, and the built and natural assets that could be impacted
- Phase 2| Sensitivity: Assess the degree of damage or disruption sea level rise and storms could cause on the exposed assets.
- Phase 3| Adaptive Capacity: Assess each asset’s adaptive capacity, or ability to respond successfully, to sea level rise and storms.
- Phase 4| Potential Impacts: Evaluate the potential consequences to the assets and larger context, assuming no intervention actions.
- Phase 5| Risk & Onset: Describe the certainty and timing of impacts.
Key Findings
In the coastal zone of Marin County, over 10 percent of buildings are vulnerable to a scenario with 40 inches of sea level rise and a 100-year storm. In a scenario of 80 inches of sea level rise combined with a 100-year-storm event, even 20 percent of buildings at the coast would be vulnerable. Depending on the scenario between 2.5 and 20 miles of road may be exposed to sea level rise and storm flooding.
Other vulnerable assets of coastal Marin are:
- Beaches,
- underground on-site wastewater treatment systems
- Water distribution pipe
- Fire service facilities and tsunami routes
- Recreational facilities
More information and the pdf version of the Vulnerability Assessment can be found here: http://www.marincounty.org/depts/cd/divisions/planning/sea-level-rise/draft-vulnerability-assessment
As stated in the document, the assessment is not a regulatory or legal framework but an advisory report. Based on the assessment, adaptation measures can be undertaken. Implementing these measures, new institutional, legal, and financing arrangements might be required. The assessment lays the informational foundation for adaptation planning and implementing the necessary measures.