Established in 1912, the Marin Municipal Water District provides high-quality drinking water to 191,300 customers in central and southern Marin County. Seventy-five percent of our water comes from more than 21,600 acres of protected watershed on Mt. Tamalpais and in the grassy hills of west Marin. Rainfall from these watersheds flows into one of MMWD’s seven reservoirs. This reservoir water is then treated at one of the district’s potable water treatment plants before traveling to customers’ homes and businesses.

Twenty-five percent of MMWD’s water is imported from the Sonoma County Water Agency (SCWA). SCWA water originates from rainfall that flows into Lake Sonoma and Lake Mendocino and is released into the Russian River. The Russian River water is filtered naturally through 80 feet of sand beds adjacent to the river. The Russian River water is blended with MMWD’s reservoir water in the distribution system.

Our Mission

To manage our natural resources in a sustainable manner and to provide our customers with reliable, high quality water at a reasonable price.

Municipal Water District Act

MMWD was formed by the California Legislature under the Municipal Water District Law of 1911 (State Water Code Section 71000). MMWD is a governmental agency authorized under Section 71000 of the California Water Code for the purpose of providing an adequate supply of water within its service area.

Public Records Act Requests

Public Records Act requests may be submitted to the Marin Municipal Water District online, by regular mail, by email, or by fax.

  1. Online: Public Records Act Request Form
  2. Mail: Marin Municipal Water District, Re: Public Records Act Request, 220 Nellen Avenue, Corte Madera, CA 94925
  3. Email: publicinformation@marinwater.org
  4. Fax: 415-927-4953

Please allow up to ten calendar days to receive a response to your request. Fees may apply.

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MMWD Fact Sheet Print Friendly Version
Service Area
Square miles
Population 191,300
Budget fiscal year revenues for FY2020 (not including fire flow)
Budget fiscal year disbursements for FY2018 (not including fire flow)
     Operations $77,880,158
     Debt service
     Capital purchase and projects
Total budgeted fiscal year disbursements
Utility plant - net book value
(per audited financial statement as of 6/30/19)
Water Supply
Watershed Lands (acres)
Number of storage reservoirs
Total reservoir storage capacity in acre-feet (1)
     In millions of gallons
Average yearly rainfall in inches at Lake Lagunitas
Average yearly runoff, less losses (2), in acre-feet
     In millions of gallons
Water imported from the Russian River (10-year avg. annual acre-feet)
Operational yield (3) (acre-feet)
Water Production
Service connections (active)
     Other (commercial, institutional, irrigation)
Maximum annual use (1987) in acre-feet
     In millions of gallons
Average annual use from fiscal year 2008-2019 in acre-feet
     In millions of gallons
Water Facilities
Potable Recycled
Miles of pipeline
883 24
Number of storage tanks
124 3
Total tank storage capacity (in millions of gallons)
82 1.9
Number of pump stations
94 3
Number of water treatment plants
3 0
Maximum daily treatment plant capacity (in millions of gallons)
71 0
Average daily treatment plant production (in millions of gallons)
21 0
Watershed Facilities
Miles of watershed roads
Miles of watershed trails
Number of picnic grounds
Acres of wildfire fuel reduction area
(1) One acre-foot is equivalent to 325,851 gallons, enough water to cover one acre (about the size of a football field) to a depth of one foot or to supply three families for one year
(2) Due to evaporation
(3) Amount of water that can be supplied in all but the driest years