Environmental Impact Report to be prepared for Atmospheric River Capture Project

Graphic shows various stages of water delivery and treatment.

Notice of Preparation: Environmental Impact Report to be prepared for Atmospheric River Capture Project

Pursuant to the California Environmental Quality Act, Marin Water is initiating environmental review for the proposed Atmospheric River Capture (ARC) Project. This process begins with an initial comment period for agencies and the public to provide input on the scope of environmental issues to be addressed in the Project’s Environmental Impact Report (EIR). This scope is described in the following Notice of Preparation documents for the Project:

COMMENT PERIOD FOR THE SCOPE OF THE EIR

The initial public comment period – which is for the scope and content of the EIR and Project alternatives to consider – will be open until noon on April 13, 2026. Comments must be submitted before the deadline and may be provided in one of the following ways:

  • By U.S. postal mail to:
    Marin Water
    Attn: ARC Project
    220 Nellen Ave.
    Corte Madera, CA 94925
  • In Person (at a Scoping Meeting)

As part of the environmental review process, Marin Water is holding two public scoping meetings. These meetings are an opportunity for interested parties to learn more about the project and provide comments on the scope of environmental issues to be addressed in the Project’s EIR. Note: The information provided will be the same for both meetings.

  • Wednesday, March 25, 2026, from 6:00–7:00 PM
    Novato Recreation Center – 950 7th St., Novato

   OR

  • Thursday, March 26, 2026, from 5:30–6:30 PM
    San Ramon Elementary School, Multipurpose Room – 45 San Ramon Way, Novato

DESCRIPTION OF PROPOSED PROJECT

The Marin Municipal Water District (District) is proposing the Atmospheric River Capture Project (Project) to deliver water under the District’s existing agreement with the Sonoma County Water Agency (Sonoma Water) to Nicasio Reservoir for storage to improve water supply reliability under dry conditions.

The Project would include construction and operation of an approximately 13.2-mile-long, 36-inch diameter water transmission pipeline within Wood Hollow Drive, Redwood Boulevard, San Marin Drive, Novato Boulevard, Point Reyes–Petaluma Road, and Nicasio Valley Road. The pipeline, referred to as the Nicasio Aqueduct, would convey water from the existing North Marin Aqueduct to Nicasio Reservoir. In addition, the Project would include two pump stations and a dechlorination facility.

The Project would not increase the existing storage capacity of Nicasio Reservoir and would not modify the District’s existing agreement with Sonoma Water. The Project would deliver contract water from Sonoma Water for storage in Nicasio Reservoir during periods of high-flow events (i.e., atmospheric river events) for use by the District during dry conditions to improve water supply reliability.

More information on the Project can be found on Marin Water’s Atmospheric River Capture Project webpage.

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