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Water Supply Planning

Bon Tempe Reservoir view of Mt Tam

About Our Supply

Local Reservoirs & Sonoma Imports

About 75% of the District's water supply originates from rainfall on our Mt. Tamalpais watershed and in the grassy hills of west Marin, flowing into the District’s seven reservoirs. The District also supplements its supply with water from the Sonoma County Water Agency (SCWA), which comes from the Russian River system in Sonoma County. The Russian River water supply originates from rainfall that flows into Lake Sonoma and Lake Mendocino. 

Recycled Water

To decrease the demand for potable drinking water and stretch our water supply, Marin Water through a partnership with the Las Gallinas Valley Sanitary District, provides recycled water year-round currently to 330 customers in Terra Linda area of San Rafael for a range of uses including irrigation, industrial cooling, and toilet flushing. The District also provides customers with industry-leading Water Use Efficiency programs. These programs are a critical component of our overall water supply planning efforts as they support our customers in reducing their current and future demand for water sustainably.

Water Supply and Demand Data

Water Supply Planning

The District is committed to long-term water supply planning to ensure adequate water supplies are available to meet current and future water demands under varying water supply conditions. Planning ahead is important so that we are ready and resilient, and able to supply water to our customers for generations to come.

Strategic Water Supply Assessment

Severe conditions brought on by the drought in more recent years have intensified the District’s focus on strengthening the reliability of its water supply. The District is currently conducting a Strategic Water Supply Assessment intended to evaluate the Districts current baseline water supply in the context of climate-change-driven droughts and to evaluate the impact of potential future water management alternatives that could improve the District’s long term water supply resiliency. These efforts will help the district ultimately determine which options are viable, affordable, and make the most sense for our community and the region.

Water Resources Plan 2040

In 2017, the district prepared the Water Resources Plan (WRP) 2040 to evaluate resiliency in the face of a variety of threats to water resources in its service area and to identify options to enhance resiliency for its customers. The WRP 2040 provides valuable information to enable the District to make informed water supply planning decisions in the face of a variety of potential reliability threats.

Urban Water Management Plan

In compliance with the California Water Code, the District updates and adopts its Urban Water Management Plan (UWMP) and submits it to the Department of Water Resources every five years. The UWMP provides information about the District’s water system, its water supply sources, historical and projected water use, and a comparison of water supply to water demands during normal, single-dry, and multiple-dry years. It also reports on the District's compliance with State mandated water conservation targets and provides detailed information about demand management measures. The 2020 UWMP was adopted by the Board of Directors in 2020.

Water Shortage Contingency Plan

The California Water Code also requires the District to prepare an updated Water Shortage Contingency Plan (WSCP) every five years, though the plan can also be amended at any time. The WSCP defines water shortage levels and identifies corresponding response actions and procedures for reducing demand for water during mild to severe droughts or other water shortage conditions. An Amended 2020 Water Shortage Contingency Plan was adopted by the Board of Directors on February 21, 2023.