UPDATE: The Marin Municipal Water District has just announced a significant investment of $387,685 to conduct an urgent study addressing serious flooding concerns in Nicasio. This decision follows intense resident protests against a now-canceled plan to expand the Nicasio Reservoir, which locals feared would worsen existing flooding issues.
Residents have voiced alarm over increased flooding along Nicasio Creek and Halleck Creek, both crucial waterways within the district. Flooding has already caused considerable damage to roads, yards, and the community school, prompting urgent calls for action. The district’s board convened on November 18, 2025, to approve the study, which aims to identify the causes of reduced creek flow and evaluate long-term management solutions.
Ben Horenstein, general manager of the district, stated, “What we found is, without question, there’s district responsibility.” He emphasized the need to address the impacts on the community and the environment. Meanwhile, Matt Samson, chair of the board, acknowledged the high cost of the study but underscored its importance: “I think it’s merited, and I think it’s on us.”
The previous proposal to modify the Nicasio Reservoir’s spillway gates aimed to increase water supply by enhancing capacity. However, when project costs skyrocketed from an estimated $10 million to $15 million to a staggering $37 million to $54 million, the board opted to terminate the plan. Residents celebrated this decision but have since demanded that the district take responsibility for flooding relief.
The Environmental Science Associates has been contracted to conduct the study, which is not linked to any further spillway modifications. Instead, it focuses on gathering objective, science-based information regarding current creek conditions. According to spokesperson Adriane Mertens, the study will help engage key stakeholders to ensure ongoing communication and transparency.
Community leaders, including Martha Davis of the Nicasio Landowners Association, expressed gratitude for the district’s commitment to addressing flooding. “The question about continuous monitoring is going to be really important because this is not a one-and-done,” Davis stated, highlighting the need for a sustainable approach to managing the ecological system.
In addition to the flood study, the district is pursuing emergency permits to remove accumulated debris from district-owned portions of Nicasio Creek, further aiming to alleviate flood risks. If approved by the San Francisco Bay Regional Water Quality Board, this debris removal is expected to take about two to three weeks.
As the district continues to address these pressing concerns, residents are keenly watching for updates on both the flood study and the proposed atmospheric river capture project, which would involve a new pipeline to transport water from the Russian River to the Nicasio Reservoir. Community members are anxious about the reservoir’s capacity to handle additional water, especially during drought conditions.
Stay tuned for further updates as the Marin Municipal Water District works to tackle these urgent flooding issues in Nicasio. The outcomes of the study and the district’s ongoing efforts will be critical for the safety and well-being of the community.
