For Immediate Release –
San Rafael, CA –
Seasonal elevated levels could impact areas with history of localized flooding
Seasonal high tides can cause flooding along shoreline communities and low-lying roads in Marin County. Tide-related flooding can happen whether it is raining or not, but flooding can increase significantly if the elevated tides occur during a storm, potentially obstructing roads and impacting commute times and travel plans.
Based on tide predictions[External] published by the National Oceanic and Atmospheric Administration[External] (NOAA), tide levels that could be high enough to cause roadway flooding in coastal and bayside areas of Marin are expected November 22-27, December 20-26, and January 18-23. If a storm happens at the same time, it can cause a tidal surges and push water levels significantly higher than predicted.
Coastal communities and areas historically susceptible to flooding have a higher chance of being impacted. That tends to be most prevalent in areas of Marin where signs of sea level rise are already causing year-round tidal flooding issues. Some of those locations are North San Pedro Road through China Camp in unincorporated San Rafael, Greenwood Cove Drive in Tiburon, Lucky Drive in Greenbrae, Redwood Highway at Greenbrae Boardwalk, Marin City, and the Manzanita Park & Ride lot near Tam Junction.
The Marin County Department of Public Works (DPW) and the Marin County Flood Control and Water Conservation District (District) are urging residents and visitors to be aware of the predicted seasonal high tides. Drivers should allow extra time for trips and should be prepared to use alternative routes to avoid localized flooding on roadways. Travelers should always avoid driving through standing water, as even six inches of depth can stall a vehicle.
Residents are encouraged to plan ahead and take action on their own property to help reduce flood risk. In advance of storms, property owners should clear dead leaves from driveway pipes, rooftop gutters, and storm drains. Dead foliage needs to be placed in compost bins, not put in streets where it will clog neighborhood drainage systems. Those living in flood-prone areas should test their sump pumps and stock up on sandbags (available at most hardware stores), as well as learn how to properly use[External] them prior to storms. Additionally, ReadyMarin.org[External] provides detailed resources, including emergency grab-and-go packing checklists, that can be helpful for residents to prepare for the unexpected.
The following chart shows predicted high tides at or above 6.4 feet (rounded up to the nearest tenth) through January 2023 at the NOAA San Francisco tide gauge[External].
|Day||Elevation in Feet (MLLW)|
|Tuesday, November 22, 9:33 a.m.||6.4|
|Wednesday, November 23, 10:07 a.m.||6.6|
|Thursday, November 24, 10:44 a.m.||6.8|
|Friday, November 25, 11:27 a.m.||6.8|
|Saturday, November 26, 12:14 p.m.||6.7|
|Sunday, November 27, 1:07 p.m.||6.4|
|Tuesday, December 20, 8:15 a.m.||6.4|
|Wednesday, December 21, 8:55 a.m.||6.7|
|Thursday, December 22, 9:38 a.m.||7.0|
|Friday, December 23, 10:24 a.m.||7.1|
|Saturday, December 24, 11:14 a.m.||7.1|
|Sunday, December 25, 12:06 p.m.||6.9|
|Monday, December 26, 1:01 p.m.||6.5|
|Day||Elevation in Feet (MLLW)|
|Wednesday, January 18, 7:36 a.m.||6.5|
|Thursday, January 19, 8:28 a.m.||6.8|
|Friday, January 20, 9:22 a.m.||7.0|
|Saturday, January 21, 10:15 a.m.||7.2|
|Sunday, January 22, 11:08 a.m.||7.1|
|Monday, January 23, 12:01 p.m.||6.8|
Projections by the California King Tides Project[External] indicate that annual king tides, which are extreme high tides, could become the new normal tides as sea level rise continues. King tides occur when the earth, moon and sun are aligned to exert the maximum upward gravitational pull on the tides, thereby increasing overall water elevations. The project also predicts that there will be an increase in daily tidal flooding as sea levels rise. In the same vein, the County of Marin released the Marin Shoreline Sea Level Rise Vulnerability Assessment in 2017, a comprehensive study that showed the expected impacts that sea level rise will have on flooding along the eastern Marin shoreline. For southern Marin, a detailed interactive guide to sea level rise flooding can be found on the Richardson Bay Resilience website.[External]
Travelers can check 511.org[External] for latest traffic and transit information. During storm events, DPW’s Twitter[External], Marin County Sheriff’s Office’s Twitter[External], the California Highway Patrol (CHP) traffic website[External] and CHP Marin’s Twitter[External] are all excellent resources for travelers and residents looking for updates. Another resource is the Marin County emergency portal, which provides a range on helpful information and links. Additionally, weather gauges showing rainfall and tide elevations can be viewed in real-time at Marin County’s OneRain webpage[External].