For the second time, Marin Water has extended the public comment period for its proposal to raise the Nicasio Reservoir dam, as residents raise new questions about the proposal’s potential impacts. The district, which has held four public meetings on the plan, will continue collecting public comment through the end of the year as it considers which issues to examine in an environmental impact report on the plan. Raising the spillway at the Seeger Dam is one of several short-term steps that Marin Water is considering to enhance its ability to endure future droughts. The proposal calls for a 280-foot-long, 4.4-foot-high inflatable rubber gate spanning the top of the spillway that would be inflated during the wet season to increase storage and lowered during the dry season. But since the proposal was announced last fall, Nicasio residents have warned that higher reservoir levels would exacerbate flooding, already a problem at several homes along the banks of Nicasio Creek. More recently, Point Reyes Station residents raised concerns about downstream impacts if the rubber gate were to fail. The Point Reyes Station Village Association will invite district officials to brief the group on the project, said Steve Antonaros, the association’s president. Adriane Mertens, a spokeswoman for the water district, said staffers have met with interested individuals and community groups and are open to more meetings. “The district is appreciative of the comments received to date and staff are continuing to evaluate and assess project information as it comes in,” she said. Eric Moeller, an Inverness resident and engineer with who has experience working on dams for international mining companies, recently assessed the proposal for the Point Reyes Station Village Association. He fears a rubber gate would be prone to vandalism by people taking pot shots with guns or puncturing it with a knife. In an email to the village association, Mr. Moeller suggested that deepening the reservoir by digging it out during periods of drought would provide a better solution. In fact, Marin Water considered dredging the reservoir as one of many options for increasing supply, Ms. Mertens said. “While dredging was considered, it was ultimately not moved forward due to concerns about feasibility, cost, environmental impacts and the extended timeframe required to implement such a project,” she said. A 2023 report by the Marin County Civil Grand Jury included state inundation maps that showed that substantial portions of Point Reyes Station would be flooded if the Nicasio spillway were to fail. The report also cited dam risk hazard ratings from the California Division of Safety of Dams, which are broken into four categories: low hazard, significant hazard, high hazard and extremely high hazard. Dam failure in extremely high hazard areas would cause considerable loss of human life. By contrast, dam failure in high hazard areas would cause the loss of at least one human life and significant economic losses and environmental damage. Seven of Marin’s eight reservoir dams—including the Seeger Dam—are in the high hazard category. The state maintains separate safety classifications to assess the physical condition of dams, and all eight in Marin received a satisfactory rating, the highest of four classifications.