Atmospheric River Capture Project

The Marin Municipal Water District (District) is proposing the Atmospheric River Capture Project (Project) to deliver water under the District's existing agreement with the Sonoma County Water Agency (Sonoma Water) to Nicasio Reservoir for storage to improve water supply reliability under dry conditions. Since publication of the March 2026 NOP, the Project has been revised to include the development and implementation of a long-term management plan to address sediment and vegetation buildup in Upper Nicasio Creek in the unincorporated community of Nicasio. This includes vegetation and sediment removal, approximately 50,000 cubic yards, over at least two construction seasons along approximately 3,150 linear feet of Upper Nicasio Creek and 1,200 linear feet of Halleck Creek; lowering the existing delta sediment deposits in Nicasio Reservoir by approximately 4 feet to create a lowered bench approximately 100 feet wide along 2,000 linear feet of the right bank of Upper Nicasio Creek; maintenance activities on an as-needed basis; staging in designated areas; and off-hauling of vegetation and excavated sediment to an off-site location for disposal or reuse. Additional Assessor's Parcel Numbers include: 121-230-24, 121-070-11, 121-050-46, 121-050-43, 121-050-34, 121-050-13, 121-050-45, 121-050-74, 121-050-11, 121-090-05, 121-090-04, and 121-090-03.