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Marin Water kicks off environmental review of Nicasio Spillway Project

A reservoir and spillway.

Pursuant to the California Environmental Quality Act, Marin Water is initiating the environmental review of the Nicasio Spillway Modification Project. Modifying Nicasio Reservoir’s spillway is one of the near-term storage enlargement projects identified through development of the District's Water Supply Roadmap.  

The reservoir's current storage capacity is 22,340 acre-feet. This project would install a 280-foot-long, 4.4-foot-high inflatable rubber gate spanning the width of the existing spillway crest of Seeger Dam. The modification to the existing spillway would provide approximately 3,700 acre-feet of additional temporary water storage capacity. The Project would increase locally stored water supplies in the near-term to reduce adverse effects on Marin Water customers caused by water shortages from droughts and other emergencies. 

The review process begins with a comment period for agencies and the public to comment on the scope of the environmental review, including the project description, environmental issues to be analyzed and potential alternatives. These issues are described in a Notice of Preparation

Comment Period

The public comment period will be open from April 30, 2025 to 5 p.m. June 4, 2025. Comments must be submitted before the deadline and may be provided in one of the following ways:

  • By email to
    Elysha Irish
    eirish@marinwater.org 
    Subject: Nicasio Spillway Modification Project public comment
     
  • By U.S. postal mail to:
    Marin Water
    Attention: Elysha Irish
    220 Nellen Ave.
    Corte Madera, CA 94925

Scoping Meetings

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. The information presented will be the same for both meetings.

Scoping Meeting 1
Thursday May 22, 6-8 p.m.

Online:
https://marinwater.zoom.us/j/84070451584 Dial-in Number: 1-669-444-9171 
Webinar ID: 840 7045 1584  

   OR

In person:
Marin Water Board Room
220 Nellen Ave.
Corte Madera, CA 94925

Scoping Meeting 2
Tuesday May 27, 1-3 p.m.

This meeting is online only:
https://marinwater.zoom.us/j/83247604594
Dial-in Number: 1-669-444-9171 
Webinar ID: 832 4760 4594

 

Project Information and Background

Read the proposed project description and background on the Nicasio Spillway Modification Project page