Since 1969, California has required all local governments to plan to meet the housing needs of all persons in the community regardless of income and/or special housing needs. California’s city and county governments meet this requirement by adopting housing plans (called housing elements) as part of their general plan, also required by the State. Marin County’s general plan is called the Marin Countywide Plan. General plans guide how a jurisdiction will grow, manage environmental resources, and protect residents and businesses from naturally occurring and human-caused hazards. The planning process includes identifying where future housing will be developed. This Map Atlas identifies the physical considerations that need to be considered in planning for any type of new development—but focused in particular on potential sites for new housing to meet current and future housing needs in Marin County’s unincorporated communities.


Planning to meet housing needs for all Californians involves a statewide approach directed by the Department Housing and Community Development, or HCD. HCD identifies long-term housing need and allocates absorption of that need to regional councils of government. In the Bay Area, that council is the Association of Bay Area Governments (ABAG). The housing allocation is called the Regional Housing Needs Allocation—the RHNA. The RHNA quantifies the “fair share” number of housing units each jurisdiction must plan for to meet regional objectives.

The ABAG region has been assigned a RHNA of 441,176 housing units for the eight-year period of 2023-2031. Marin County’s draft RHNA allocation is 3,569 units, with those units distributed among four household income categories, as illustrated in the adjacent graphic. ABAG is in the process of finalizing each jurisdiction’s final RHNA, with the final allocation issued in December 2021.


In the summer of 2021, Marin County initiated a program to update the Countywide Plan’s Housing Element and to engage community members in crafting housing policies and identifying potential sites for new housing for people of all income levels and housing needs. The updated element must be adopted by the Board of Supervisors by the end of January 2023. While that may seem a distant future, the process of identifying housing sites requires thorough and thoughtful investigation and extensive community dialogue to reach the most appropriate solutions. Central to this investigation is providing common public understanding of the environmental and infrastructure constraints to housing development. Marin County has many features and landscapes considered incompatible with development in any form, from wildfire dangers and flooding hazards to valuable agricultural lands and sensitive ecosystems.


In conjunction with the Housing Element update, the County is updating Countywide Plan components related to public safety planning. The changing climate is having impacts we witness today: new temperature extremes, increase in the frequency and severity of wildland fires, drought conditions, and rising sea levels. These circumstances affect decisions about where to allow new housing development and how to guard against threats to people and property from these hazards. By updating policies related to public safety planning, the County will establish a new framework for land use decision-making based on known and anticipated conditions.


As part of the Housing and Safety Element update process, we want to use mapping resources to help the community understand the opportunities and constraints that influence decisions of where to locate future housing and how to protect the community over the long term. These maps allow the public to:

  • Understand the regional housing obligation (accommodate 3,569 housing units in the County over the next eight years) and the County’s goal to accommodate the housing in a manner sensitive to the resources and other assets that define Marin County.
  • Provide a common public understanding and recognition of the factors (existing conditions and constraints) that influence the decision-making process in accommodating new housing units.
  • Encourage the community to identify and provide input on the locations for housing to meet the RHNA.