Marin County Water Providers

Marin County has two cooperating agencies that supply our drinking (potable) water to most of our ca. 260,000 residents:

• Marin Water (previously known as Marin Municipal Water District or MMWD) serves southern and central Marin from Sausalito through San Rafael and the San Geronimo Valley in West Marin.
• North Marin Water District (NMWD) serves the City of Novato plus the rest of West Marin, except for Muir Beach, Stinson Beach, and Dillon Beach, and Bolinas, which have their own water distribution systems.

Marin Water (MMWD)

Seventy-five percent of the drinking water for southern, central Marin, and West Marin’s San Geronimo Valley comes from 22,000 acres of protected watershed on Mount Tamalpais. Winter rains, typical from October through March, collect in five man-made reservoirs on Mt. Tamalpais and two reservoirs in the hills of northern Marin.

MMWD has seven local reservoirs:

• Alpine Lake
• Bon Tempe Lake
• Kent Lake
• Lake Lagunitas
• Nicasio Reservoir
• Phoenix Reservoir
• Soulajule Reservoir

 

These seven reservoirs, with a combined capacity of 79,566 acre-feet provide 75% of our drinking water. The district’s remaining 25% of water comes from neighboring Sonoma County’s Russian River Water System. Water from the Russian River supplies the City of Novato though an aqueduct; part of this water is passed on to MMWD for use in central and southern Marin. Full reservoirs plus water from Sonoma provide about a two-year supply for Marin Water.

These reservoirs provide beautiful lakes and thousands of acres for public recreational use including hiking, biking, fishing, horseback riding, and picnicking. To protect public health, swimming is not allowed. This watershed has 130 miles of trails and unpaved roads. 

North Marin Water District (NMWD)

The North Marin Water District gets most of its water supply from the Sonoma County Water Agency. 80% is sourced from: Lake Mendicino and the Russian River in Sonoma County. The other 20% is collected in a local reservoir, Lake Stafford.

The NMWD serves two different suburban areas:

• Novato, which has a service area of 75 square miles and a customer population of about 62,000. The water is sourced from a groundwater aquifer adjacent to the Russian River, and directly from Stafford Lake. Together they produce about 212 million gallons a year.
• West Marin, which has a smaller area of 24 square miles and a customer population of about 1,800 residents in Point Reyes Station, Inverness Park, Bear Valley, Olema, and the Paradise Ranch Estates area. The water is obtained from groundwater wells located adjacent to Lagunitas Creek, which is then processed by the Point Reyes Water Treatment Plant.

Separate Water Supplies for Small Towns in West Marin

Several unincorporated towns in West Marin have their own water supplies:

• Muir Beach water is provided to 159 customers by the Muir Beach Community Services District. Water is sourced from two wells in the Redwood Creek Watershed.
• Bolinas sources its water from a dam on the Arroyo Hondo Creek, a few miles north of downtown. When needed, the district uses water stored in its two reservoirs, Woodrat I and 2. The Bolinas Community Public Utility District has restricted water use since 2017 due to a diminishing supply.  
• The Stinson Beach County Water District serves a population of about 608 permanent residents and up to 15,000 residents on weekends and many holidays. The district obtains the water from groundwater wells and to a much lesser extent, from local creeks. Water rationing has been required since August 2021.  
• Tomales and Dillon Beach water is provided by the Estero Mutual Water Co from wells and a reservoir. The village of Marshall also relies on well water.

Here is a map of the water districts.

Current Water Supply for Marin County

In 2023, our water storage levels are high compared to recent years. In March, Governor Gavin Newsom lifted some of the statewide drought restrictions. During a wetter-than-average winter, the statewide voluntary use reduction of 15% was eliminated and a mandate that local water agencies operate under Level 2 drought restrictions was rescinded. The announcement did not constitute an official declaration that the drought was over. There are still restrictions on water use in Marin (see the following).

Restrictions for Marin Water (MMWD)

These are the current water restrictions in areas served by MMWD (September, 2023):

• Irrigation of residential properties is allowed only prior to 9 a.m. or after 7 p.m.
• Watering with overhead sprinkler irrigation systems is limited to two times per week and watering with drip irrigation systems is limited to three times pe week (watering days are not assigned).
• Irrigation systems must not have overspray or runoff.
• Potable water shall not be used for irrigating during and within 48 hours after rainfall.
• Irrigation of purely decorative lawns in commercial, institutional, and industrial sites is prohibited. Irrigation of decorative lawns in common area landscapes of homeowners’ associations is also prohibited. (This rule does not apply to lawns actively used for recreational sports, events, or other civic purposes.)
• The refilling of a completely drained swimming pool and the initial filling of any swimming pool for which application for a building permit was made after December 1, 2021, will not be allowed.
• Covers are required for all pools and spas.
• Do not wash driveways, sidewalks, walkways, parking lots or any other hard surfaced areas with a hose.
• Do not waste water. Flooding gutters is prohibited as is excess water runoff flowing onto the public right-of-way.
• Leaks must be fixed within 48 hours of being discovered.
• Garden hoses must have a shutoff nozzle.
• Do not water grass on public medians.
• Do not refill or top off non-recirculating decorative fountains.
• Non-recirculating systems for conveyer carwashes and single pass cooling systems are prohibited for new connections. 
• Reverse osmosis water purifying systems must be installed with an automatic shutoff unit.
• Sewer cleaning/flushing should be done using recycled water when available without having hauling by truck and whenever reasonably possible.

To learn more about Marin Water drought restrictions click here.

Restrictions for the North Marin Water District

In Novato, only these activities are prohibited:

• Gutter flooding (unreasonable irrigation overspray or irrigation run-off onto pavement, down a gutter, ditch, or other drain).
• Failure to repair a controllable leak of water within a reasonable time.
• Washing privately-owned motor vehicles, trailers, and boats except from a bucket and hose equipped with an automatic shut-off nozzle for a quick rinse.
• Washing down exterior paved areas.
• Watering during or within 48 hours of measurable rainfall.
• No use of potable water for street cleaning or construction purposes, unless no other source of water or other method can be used or if necessary, to protect the health and safety of the public (state mandate).

To learn more about NMWD water restrictions for Novato, see the Novato Service Area Water Waste Prohibitions. [https://nmwd.com/save-water/drought/novato-service-area-guide/]

In West Marin, the restrictions include:

• Using water for non-recycling decorative fountains or single pass cooling systems.
• Washing down exterior hard surface areas.
• Permitting water to escape down a gutter, ditch, or other surface drain.
• Irrigation which allows excessive runoff or unreasonable overspray.
• Failure to repair a controllable leak of water within a reasonable time.
• Washing cars, boats, trailers or other vehicles and machinery directly with a hose not equipped with a shutoff nozzle.

You can read here the details of water restrictions in the West Marin service area.

Providing Water in Future Years

It is unlikely that the most recent drought of 2020-2023 will be California’s last. To deal with our water needs in future years, there are several possible solutions:

• Conserving water. While this will always be required, alone it will not solve the supply problem.
• Building new dams or increasing the effective use of existing dams. These solutions are controversial and expensive. 
• Desalinization. This is an option that works for many locations in the world. MMWD has been contemplating desalination on and off since the early 1990s and has tested two pilot desalination plants. This is still an option that deserves consideration. You can read an informative argument in favor of desalinization  from the Marin Independent Journal, 2021.
• Building a pipeline over the Richmond-San Rafael Bridge. This pipeline would bring water purchased from farmers in the central valley. This solution was used in the last major drought. It works only if there is water that we can buy.
• Importing more water from Sonoma County. Our present contract with Sonoma Water allows Marin to purchase 14,300 acre-feet of water annually, but constraints in the district’s transmission and distribution system allow only 11,000 acre-feet to be imported per year. We could improve the system to import an additional 3,300 acre-feet. However, the cost might make this option impractical. Also, in a drought year Sonoma may not have water to spare.

The Marin Independent Journal frequently publishes updates on these options. You can obtain digital access to the Marin IJ at a low introductory rate..