UPDATE: The Marin Municipal Water District has just announced a significant investment of $387,685 to urgently investigate flooding concerns in Nicasio, California. This decision follows intense resident protests against a now-canceled plan to expand the Nicasio Reservoir, which locals fear could worsen flooding conditions.
Residents have reported increased flooding along Nicasio Creek and Halleck Creek, resulting in damaging impacts to roads, yards, and the community school. With the flooding frequency rising, community members are calling for immediate action to address the situation.
During a board meeting on November 18, 2025, the district officially approved a contract with Environmental Science Associates to conduct the study. District General Manager Ben Horenstein confirmed, “Without question, there’s district responsibility,” emphasizing the urgency for the district to address the growing concerns regarding stream conditions and property management.
Board Chair Matt Samson acknowledged the costly nature of the study, stating, “I think it’s warranted…it’s going to help us manage our reservoir system altogether.” The decision comes after the district had to terminate an ambitious project that would have modified the spillway at Seeger Dam to increase reservoir capacity. Initially estimated between $10 million and $15 million, the costs unexpectedly surged to between $37 million and $54 million, leading to the project’s cancellation.
Local residents celebrated this decision but assert that the district still holds a responsibility to mitigate flooding. The primary goal of the new study is to identify factors contributing to decreased creek flow and explore long-term solutions to alleviate flooding impacts. District spokesperson Adriane Mertens noted, “The study is focused on meeting our commitment to gather objective, science-based information about current creek conditions.”
Community members, including Martha Davis from the Nicasio Landowners Association, expressed appreciation for the district’s prompt response. Davis highlighted the need for ongoing monitoring, stating, “This is a living ecosystem…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 flooding study, the district is pursuing emergency permits from the San Francisco Bay Regional Water Quality Board to remove accumulated debris from Nicasio Creek. This removal is critical for ensuring water flows more freely towards the reservoir, reducing flood risks. If approved, the operation is expected to take about two to three weeks.
Residents have also raised concerns regarding the district’s proposed “atmospheric river capture” project, which aims to carry water from the Russian River into the Nicasio Reservoir. Many fear that the reservoir may not have the capacity to handle the increased influx.
As the Marin Municipal Water District moves forward with these initiatives, the community remains vigilant, hopeful for a resolution to their flooding struggles. The district’s commitment to understanding and addressing these environmental challenges demonstrates a proactive approach in managing water resources effectively in Nicasio.
Stay tuned for updates as the situation develops and the study progresses.
