A crane rolled onto the vacant lot at 156 Shoreline Highway in unincorporated Mill Valley yesterday, staging equipment for the modular apartment building that's supposed to rise on the site — even though the county previously issued a stop-work order after construction began while building permits were still being finalized. Underground site work is already done, and once the outstanding permits clear, crews expect assembly of the prefabricated modular sections to take about two weeks.
The update comes straight from Marin County, which posted that construction activity is progressing at the 32-unit affordable housing development in the Tam Valley area, known locally as the Shoreline Highway Apartments. The site sits near the junction of Highway 101 and Shoreline Highway, directly across from the Manzanita Park & Ride lot — a location that's been a flashpoint for parking and traffic concerns since the project was first proposed.
Construction activity is progressing at the 32-unit affordable housing development at 156 Shoreline Highway in unincorporated Mill Valley.
— Marin County (@maringov) August 25, 2026
Read the full news release: https://t.co/s4hzuUB9dv pic.twitter.com/KqdWfBPBGi
A Site With a Complicated Past
The 0.58-acre parcel wasn't always a housing site. Environmental filings reviewed by the Marin County Community Development Agency show the land once operated as an Exxon gas station and received underground storage tank case closure from the Regional Water Quality Control Board back in 1996. A Phase 1 Environmental Site Assessment was completed in August 2024 before the county approved an addendum to its countywide housing element environmental report.
Pacific West Communities, the developer behind the project, purchased the vacant lot for $1.8 million in May 2024, according to the Pacific Sun. The purchase was made specifically to accommodate 32 housing units that had been relocated away from a much larger, and far more contentious, project elsewhere in Marin County.
How a 74-Unit Marin City Project Became Two Smaller Ones
The Tam Valley building didn't start out as its own project. It's the result of a compromise struck in early 2025 between developer Caleb Roope of Pacific West Communities and Marin County to split a single, controversial 74-unit building that had originally been planned for 825 Drake Avenue in Marin City, as reported by Local News Matters. That original proposal drew intense protests, lawsuits, and political pushback over concentrating low-income housing in a historically Black community, per reporting from San Rafael Patch.
The original Marin City development had been fast-tracked under California's Senate Bill 35, a 2017 state law requiring streamlined, ministerial approval of affordable housing in jurisdictions that fall short of state housing production goals. Community members criticized SB 35 for overriding local input, a tension that helped push the project toward legal challenges and, eventually, the two-site compromise now taking shape in Tam Valley and Marin City.
Financing and Physical Specs
To fund the split project, the Marin County Board of Supervisors approved expanding a tax-exempt bond financing package issued through the California Municipal Finance Authority to up to $60 million in January. Up to $21 million of that is earmarked for the 32-unit Shoreline Highway site, with up to $39 million going toward the 42-unit Marin City site — a restructuring that required updated Tax Equity and Educational Responsibility Act hearings once the single-site proposal became two.
The approved plans call for a five-story, 58-foot-5-inch building with 31 income-restricted units plus one manager's unit, ranging from 544-square-foot one-bedroom apartments to 751-square-foot two-bedroom units. Ground-floor space is set aside for residential amenities, mail and leasing offices, and four apartments, while the remaining 28 units fill the upper floors.
The project includes just seven on-site parking spaces for the entire 0.58-acre parcel, a detail that has drawn criticism from local advisory boards worried about parking capacity and traffic near the busy highway junction.
What Commuters Should Expect
Once the outstanding permits are resolved and installation begins, drivers near the northbound Highway 101 exit and Shoreline Highway should expect traffic control measures. Transport trucks are expected to arrive every 30 to 60 minutes, causing brief 60- to 90-second traffic holds over roughly a two-week period. Caltrans has been notified of the planned activity along the state highway, and work will be restricted to weekdays between 6 a.m. and 7 p.m.
The Shoreline Highway project isn't the only local effort aimed at easing South Marin's housing crunch. Nearby, Mill Valley has rolled out a $14K rental incentive pilot offering property owners up to $14,000 to convert underused homes into year-round rentals for local workers earning up to 120% of the area median income — a stopgap measure meant to house workers while larger developments like this one work through construction and permitting.
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