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Public comment period extended for Nicasio Spillway Project Environmental Review Scoping

A reservoir and spillway.

Updated May 15, 2025

NOTICE : Public Comment period extended to Dec. 31

Marin Water has extended the public comment period for the proposed Nicasio Spillway Modification Project’s environmental review scoping process to 5 p.m. Dec. 31, 2025 (the public comment period for scoping was previously scheduled to end Aug. 4). The extension will allow more time to obtain suggestions and information from agencies and the public on the content and scope of issues to consider in developing the proposed project’s Environmental Impact Report, which Marin Water is initiating work on, pursuant to the California Environmental Quality Act. This webpage has been updated to reflect the changes in the public comment period schedule. 

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. on Wednesday, Dec. 31 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 held three public scoping meetings. The meetings were an opportunity for interested parties to learn more about the project and provide comments. The information presented was the same for all three meetings.

 

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

Scoping Meeting #1 Video Recording

 

 

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

Scoping Meeting #2 Video Recording

 

 

Scoping Meeting 3
Tuesday, July 15, 1-3 p.m.

Scoping Meeting #3 Video Recording

 

Project Information and Background

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