A major bond is in the works that could boost the supply of affordable housing in Marin and the eight other Bay Area counties. Local housing advocates believe the measure would be especially beneficial to developers hoping to build smaller-scale projects in less populated areas like West Marin.

“It would be a huge game changer,” said Arianne Dar, executive director of the Bolinas Community Land Trust. “A bond like this may make it possible for us to do more innovative projects.”

The Bay Area Housing Finance Authority plans to put the bond, which would raise between $10 billion and $20 billion, before voters next year.

Leelee Thomas, an affordable housing specialist with Marin County, said such regional funding is vital. “It would allow the county to invest in affordable housing at a different level and scope than we have in the past,” she said.

Currently, affordable housing developers cobble together financing from a variety of local, state and federal sources, along with private and foundation funding. “When you look at the costs of development, all of those funding sources are not enough,” Ms. Thomas said. “We really need to subsidize our housing units at a significant level to make them pencil out.”

Housing of any kind is difficult to build in West Marin, most of which is part of the state’s coastal zone, where an extra layer of environmental safeguards is enforced by the California Coastal Commission. Affordable housing developments here are smaller than those in more heavily populated areas, and government funding for them is more limited.

Marin supervisors recently boosted the annual affordable housing allocation from $1 million to $5 million. If the bond passes, the county’s share of its proceeds would dwarf that amount.

Under current state rules, the bond would require a two-thirds vote for approval. But legislation has been introduced that would reduce the threshold to 55 percent, and a coalition of housing advocates is preparing a statewide ballot initiative that could reduce it to as low as a simple majority.

The bond would go before voters in the nine member counties of the Association of Bay Area Governments: Marin, San Francisco, Alameda, San Mateo, Santa Clara, Sonoma, Contra Costa, Solano and Napa. As long as it wins two thirds of the total vote, it would take effect in all nine counties, even those that rejected it. 

The measure would give the counties a big boost in achieving the ambitious housing targets set by the state, said Kate Hartley, director of the Bay Area Housing Finance Authority, or BAHFA.

“Our fragmented housing delivery system means cities and counties compete against each other for scarce resources, which is highly inefficient,” Ms. Hartley said. “Passing a regional bond measure means all counties will have an unprecedented amount of funds to address the region’s severe housing shortage.”

State and local governments typically sell bonds to investors to raise money for schools, roads and other infrastructure projects. Property taxpayers pay off the bonds with an extra assessment on their yearly tax bills. Ms. Hartley said previous bonds on the scale of the housing measure have added roughly $10 per $100,000 of a property’s assessed value.

The bond proceeds could be used to build or acquire new housing, renovate existing housing or support families facing the loss of their homes if their landlord decides to sell. It could give a major boost to local nonprofits working to bring more affordable housing to West Marin.

Funds from the bond would probably arrive too late to support the eight-unit project the Bolinas trust is planning on 31 Wharf Road in downtown Bolinas, Ms. Dar said, but it could be used to finance future projects in town that are now in the planning stages.

The measure could also potentially help finance the development at the former Coast Guard property in Point Reyes Station, according to Pam Dorr, director of the Community Land Trust Association of West Marin. CLAM is planning to rehabilitate 51 townhomes and apartments at the site, with some of them set aside for farm workers.

“The BAHFA funding would allow affordable housing organizations to finance the acquisition and rehabilitation of housing that is desperately needed so people can live where they work,” Ms. Dorr said.

The Coast Guard and Wharf Road projects were included in a recent “pipeline analysis” commissioned by BAHFA that cataloged 395 affordable housing developments being planned in the nine counties. These projects would provide a total of 32,944 affordable homes. Developers have begun lining up funding for them, but the analysis found that an additional $7.6 billion is needed to bring them to fruition. The bond would be used to close that gap and provide financing for future projects around the region.

The measure would put teeth into the housing targets included in the Housing Element of Marin’s Countywide Plan, which was updated in January. The element removes constraints to developing housing by streamlining zoning requirements for sites that have been cleared in advance as suitable for construction.

The element identifies sites for 3,596 housing units, more than half of them for low- and moderate-income households—but it does not include money to pay for them.