History

California’s Oldest District

Formerly known as Sanitary District Number 1 (SD1), Ross Valley Sanitary District (RVSD) has proudly served Marin County since its establishment on May 27th, 1899, making it California's oldest sewer district. The first residents of Ross Valley held large tracts of land, which facilitated the widespread use of septic tank systems. However, the completion of the North Pacific Coast Railway in 1875 led to the subdivision of these tracts, resulting in a rapid influx of new homeowners. By 1899, rising population and failing septic systems prompted an election that established RVSD. Serving Fairfax, San Anselmo, Ross, and Kentfield, RVSD became California’s first sanitary district and Marin County’s first regional agency.

In 2018, we officially changed our name from SD1 to RVSD. This explains why you may still see our manhole covers bearing the SD1 logo. Recently, we celebrated our 125th anniversary, underscoring our enduring commitment to environmental stewardship and community service. As RVSD continues to grow and innovate, we remain steadfast in safeguarding the health and well-being of Marin County residents through sustainable wastewater solutions.

First Project

RVSD's first project involved the installation of a 10-inch trunk line running from Fairfax to Greenbrae, which directed wastewater discharge into the deep-water slough of Corte Madera Creek near the present-day Bon Air Shopping Center. As Ross Valley's population continued to expand, the practice of releasing untreated wastewater into the Bay became unsustainable. 

In 1922, a bond election allocated $450,000 for the construction of 7.5 miles of trunk sewer line and a wastewater treatment facility featuring pioneering Imhoff reduction tanks, marking one of California's earliest wastewater treatment facilities. The 7.5 miles of trunk sewer line remained operational until 1985, when it was replaced due to aging infrastructure and insufficient capacity. The Greenbrae Pump Station, originally established on the site of the Imhoff reduction tanks in 1948, was rebuilt in 1984 at a cost exceeding $2 million.

Treatment Facility

In 1945, to address rising wastewater volumes, a trickling filter treatment facility was built in collaboration with the City of Larkspur and Sanitary District Number 2 (SD2). The construction of this facility was completed in 1948 at what is now 2000 Larkspur Landing Circle. Over the years, the Larkspur Landing treatment facility underwent several expansions. Notably, in 1962, its treatment capacity was raised from 3 to 4.5 million gallons per day. Monitored closely by the State Water Quality Control Board, it consistently achieved high performance, with biochemical oxygen demand removal averaging 90%.

From 1948 to 1984, RVSD operated the Larkspur Landing treatment facility until its decommissioning following the establishment of the Central Marin Sanitation Agency (CMSA). Formed in response to environmental concerns and the requirements of the mid-1970s Clean Water Quality Act, CMSA constructed a treatment plant, interceptors, and other facilities with deep-water discharge capabilities, totaling over $84 million. The formation of CMSA was driven by the findings of the East Marin/Southern Sonoma Study, which assessed advanced treatment and deep-water discharge options for seventeen wastewater agencies in Marin and southern Sonoma Counties. Established as a Joint Powers Authority (JPA) by RVSD, SD2, San Rafael Sanitation District, and the City of Larkspur, CMSA addresses environmental challenges and ensures compliance with discharge regulations under the Clean Water Quality Act. The 2019 CMSA JPA Agreement can be viewed here Version Options History Headline.

Districts & Agencies

RVSD has provided wastewater treatment and/or collection services to various districts and agencies over the years:

• From 1948 to 1985, RVSD provided wastewater treatment and disposal for SD2 (Corte Madera) and the City of Larkspur under contract.
• In 1993 the Larkspur Sanitation Area was annexed to RVSD at the request of the City of Larkspur, and RVSD took over ownership and maintenance of Larkspur’s wastewater collection system. Additionally, RVSD assumed Larkspur's Marin County contract for wastewater collection maintenance in the Murray Park Sewer Maintenance District.