The 560-foot concrete landing where a pair of 2-million-gallon water storage tanks will be constructed through Jan. 2029 near Sky Oaks and Bolinas-Fairfax roads on the Mount Tamalpais Watershed in Fairfax, Calif. (Marin Water via Bay City News)

Construction is set to begin in June on phase two of a multi-year infrastructure project that will install a pair of 2-million-gallon water storage tanks on the Mount Tamalpais Watershed.

Located near Sky Oaks and Bolinas-Fairfax roads, the Pine Mountain Tanks Project will eventually replace the Pine Mountain Tunnel, which currently stores water for Ross Valley.

The tunnel was built in 1919 and converted for water storage in 1971. The new tanks will modernize the system and be more seismically resilient.

The second phase of the project is a major milestone, Marin Water board president Matt Samson said.

“It strengthens overall system reliability; it also expands system capacity for our Ross Valley customers and provides additional water storage for firefighting — both now and for generations to come,” Samson said.

Each pre-stressed concrete tank will stand 45 feet tall and span 90 feet in diameter. The tanks will match a 560-foot-long retaining wall, built during Phase 1, and are stained brown to blend with the natural surroundings.

The 560-foot concrete landing where a pair of 2-million-gallon water storage tanks will be constructed through Jan. 2029 near Sky Oaks and Bolinas-Fairfax roads on the Mount Tamalpais Watershed in Calif. (Marin Water via Bay City News)

The $23.2 million project, funded through Marin Water’s Capital Improvement Program, is expected to continue through January 2029, with seasonal pauses.

Trail and road access near the site will be restricted during construction.

Ruth Dusseault is an investigative reporter and multimedia journalist focused on environment and energy. Her position is supported by the California local news fellowship, a statewide initiative spearheaded by UC Berkeley aimed at supporting local news platforms. While a student at UC Berkeley’s Graduate School of Journalism (c’23), Ruth developed stories about the social and environmental circumstances of contaminated watersheds around the Great Lakes, Mississippi River and Florida’s Lake Okeechobee. Her thesis explored rights of nature laws in small rural communities. She is a former assistant professor and artist in residence at Georgia Tech’s School of Architecture, and uses photography, film and digital storytelling to report on the engineered systems that undergird modern life.