Marin Municipal Water District

Water Storage Improvement Plan  | MCL Position on Water Supply | Documents and Correspondence

MMWD Kicks off EIR for Water Storage Improvement Plan (WSIP)Watershed

MMWD engineers have been working for several years on plans to replace aging storage facilities that serve as critical links in the District’s inter-watershed transfer system of treated water. Two years ago, they outlined the key elements of the project at a meeting of MCL’s Water and Watershed Committee (See MCL Newsletter January-February 2013.) At that point, engineers had narrowed down alternatives to two preferred sites, the first above “Five Corners” and Deer Park Road near Bald Hill, and the second above Phoenix Lake, off Worn Springs Road. Near Bald Hill, a 4-million gallon cement tank would replace the Pine Mt. Tunnel, which was constructed about 100 years ago to transmit water from Alpine Lake to the Ross Valley and San Rafael. Since 1970 the tunnel has been used to store three million gallons of treated water. Due to its deteriorating condition and potential water quality problems, the Tunnel is under orders to be replaced. Two 2-million gallon tanks would replace the one-million-gallon “Ross Reservoir,” (pictured) which was constructed in 1927 and is threatened by slope failure as well as out-dated engineering standards. With the three new tanks, the storage capacity for treated water would be roughly double current storage. A group from MCL by toured the sites with district engineers and came away impressed by the massive scope of the project and the engineering challenges.

On September 29, 2014, the District officially initiated a lengthy Environmental Impact Report and permitting process for the project. In the last two years, the project features have been further refined. The project now calls for reusing much of the soil excavated to reduce the tanks’ visibility to fill and revegetate the near-by abandoned Bullfrog Quarry. The overall project will begin in 2017 and take some four years to complete. The public was given the opportunity to comment on the scope of the EIR at the September meeting at Marin Art and Garden Center. Those who spoke expressed concern over the massive size of the tanks, loss of vegetation, noise and hazards of extended construction traffic, such as cement trucks and transport of excavated soil, over popular recreation roads and through urban areas, and the visibility of tanks and retaining walls in the forested landscape. MCL submitted scoping comments on these and other issues, and will be tracking progress of the environmental review in the coming months. Further information is available from MMWD at

Background and MCL position on water supply:

Water is a finite resource.  We can no longer expect to import an ever-increasing supply from other watersheds or develop major new facilities, such as energy-intensive and costly desalination, to fill the gap between supply and demand.  Marin Conservation League continues to support conservation and efficient water use as the most environmentally responsive and least expensive means of securing water supply and managing demand.

Although MCL endorsed the Marin Municipal Water District's successful 2010 ballot initiative (Measure S) to require a public vote before construction of a desalination plant, MCL does not support desalination.

The Board of Directors, at its 11/14/2010 meeting, adopted an updated water policy which states, in part: "Desalination should not be adopted as a source of supplemental water supply at this time. Progressively stronger conservation programs and improvements to the existing supply infrastructure may well enable the existing water supply sources to meet future reduced demand reliably. Prior to making any irreversible decisions regarding desalination or putting desalination to a public vote, the MMWD needs sufficient time to implement the integrated conservation, waste reduction and efficiency programs recommended above and to gauge their success in order to determine the need for supplemental water supply." See the link below for the complete document.

Documents and Correspondence

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