UPDATE: The Marin Municipal Water District has just announced a substantial investment of $387,685 to address urgent flooding concerns in Nicasio. This critical study comes after residents raised alarms over flooding linked to sediment buildup along Nicasio Creek and Halleck Creek, following the cancellation of a controversial reservoir expansion plan.
Residents previously protested a proposal aimed at increasing the Nicasio Reservoir’s capacity, suspecting it would worsen flooding. The district’s decision to investigate stems from the damage already done to local roads, yards, and the community school. Ben Horenstein, general manager of the district, confirmed, “What we found is, without question, there’s district responsibility.”
On November 18, 2025, the district board convened and approved a contract with Environmental Science Associates to conduct the study, reflecting a commitment to address the community’s needs. Matt Samson, chair of the board, acknowledged the study’s cost but deemed it essential, stating, “I think it’s merited, and I think it’s on us.”
The now-canceled reservoir proposal was intended to enhance the county’s water supply, aiming to fortify drought defenses by modifying the spillway gates at Seeger Dam. Initially estimated to cost between $10 million and $15 million, the project’s expenses skyrocketed to an alarming $37 million to $54 million, leading to its termination in August.
While residents celebrated the cancellation, they insist that the district must take action to mitigate flooding risks. The newly commissioned study will analyze factors contributing to the reduced creek flow and explore potential long-term solutions. Adriane Mertens, spokesperson for the district, emphasized, “The study is not tied to pursuing spillway modifications — it is focused on gathering objective, science-based information about current creek conditions.”
Community members, like Martha Davis from the Nicasio Landowners Association, expressed appreciation for the district’s proactive response. She highlighted the importance of continuous monitoring of the ecosystem, saying, “You’re going to need to understand how the system is responding to any of the changes that you’re making within it.”
In addition to the flood study, the Marin Water District is pursuing emergency permits from the San Francisco Bay Regional Water Quality Board to remove accumulated debris from district-owned sections of Nicasio Creek. This effort aims to enhance water flow to the reservoir and address flood risks identified by residents. If approved, this removal process is expected to take approximately two to three weeks.
As the district moves forward with these critical assessments, residents remain watchful, advocating for continued engagement on the district’s proposed atmospheric river capture project. This initiative seeks to bring water from the Russian River to Nicasio Reservoir, raising concerns about whether the reservoir can handle increased water intake.
The urgency of these developments underscores the community’s demand for accountability and transparency in managing local water resources. As the situation evolves, residents and officials alike are poised to act swiftly to safeguard Nicasio from further flooding disasters.
