Marin County’s southern bayshore communities have been flooded for six consecutive days — and the worst is still ahead. A National Weather Service Coastal Flood Advisory issued November 1 warns of up to 1.5 feet of inundation above ground in North Bay low-lying areas, as El Niño-amplified high tides push water across Highway 101 corridor roads and into neighborhoods from Mill Valley to Larkspur. Mark Merrifield of the Scripps Center for Climate Change Impacts and Adaptation warned that this season could bring “likely the highest sea levels ever recorded on the California coast” — with the first major test arriving at Thanksgiving, when king tides will be significantly higher than what’s flooding streets now.
Which Roads Are Closed Due to Marin County Flooding?
Daily high-tide flooding — peaking around midday each day — has closed or repeatedly inundated more than a dozen roads across southern Marin County since October 27. The Marin County OEM emergency portal provides real-time road closure updates for the region. In Mill Valley, Miller Avenue and Redwood Highway Frontage Road have flooded regularly during the midday high-tide window. In Corte Madera, Golden Hind Passage was cut off entirely at the height of flooding, leaving the neighborhood effectively an island; Lucky Drive has been submerged for at least five consecutive days; Fifer Avenue, the 200-block of Tamal Vista Boulevard, and sections of Doherty Drive near Riviera Circle have all seen repeated closures. In Larkspur, Larkspur Plaza Drive at Creekside has been affected.
Caltrans has repeatedly closed the northbound U.S. Highway 101/Highway 1 interchange ramp in Mill Valley. Reporting by NBC Bay Area on the Caltrans closures includes Caltrans spokesperson Matt O’Donnell’s assessment: the ramp “has had to close that same ramp quite a few times this month” and residents “should stay on alert.”
Travelers should check the Marin County emergency portal at emergency.marincounty.gov before driving into the North Bay, particularly in the 11 a.m. to 2 p.m. PT window when tidal peaks are highest. Bypassing a road closure barricade carries a $100 fine; Corte Madera Public Works issued its first citation of the season on October 29.
Why Driving Through Floodwaters Makes Damage Worse
Officials are warning that drivers navigating flooded streets — even slowly — are causing additional harm to homes and garages. According to Bob Bundy of the Corte Madera Flood Board, vehicles traveling through shallow floodwaters generate wakes that push “another 2, 3, 4 inches of damage inside the garage” of neighboring properties. Full coverage of the flooding event, including resident accounts and official warnings, is in ABC7’s live updates on Bay Area high-tide flooding…