Marin Flood Simulation
Raise the water and see where it reaches along the Marin shore. For what the water is doing right now, see Marin flooding today.
Water depth
Water level
7.0 ft
Try a level
Tap the map
See the ground height at any spot and the water level that first reaches it.
A model of still water, not a forecast. Elevation: USGS 3DEP lidar via AWS Terrain Tiles. Imagery: Esri. Live level: NOAA San Francisco gauge.
Low Spots Along the Marin Shore
How high the low ground sits at well known flood spots, and how it compares with the biggest tide predicted for the next 12 months, 7.0 ft on Dec 24, 2026. Levees, seawalls, tide gates and pumps keep many of these places dry when the bay is higher than the land behind them. The map's level is where water reaches the ground with none of the gates or pumps in the way, so read it as the level where trouble starts, not a promise of flooding.
| Place | Low ground | Vs. 7.0 ft king tide | Map: water reaches it at |
|---|---|---|---|
| Manzanita Park and RideMill Valley | 7.3 ft | 0.3 ft above | 7.0 ft |
| Bayfront ParkMill Valley | 9.9 ft | 2.9 ft above | 6.3 ft |
| Gate 5 RoadSausalito | 7.7 ft | 0.7 ft above | 7.0 ft |
| Blackie's PastureTiburon | 10.0 ft | 3.0 ft above | 7.6 ft |
| Paradise DriveCorte Madera | 8.5 ft | 1.5 ft above | 6.3 ft |
| Town CenterCorte Madera | 6.0 ft | 1.0 ft below | 6.3 ft |
| The VillageCorte Madera | 8.5 ft | 1.5 ft above | 6.3 ft |
| Larkspur Ferry TerminalLarkspur | 10.3 ft | 3.3 ft above | 7.2 ft |
| Boardwalk OneLarkspur | 6.3 ft | 0.7 ft below | 6.1 ft |
| Greenbrae BoardwalkLarkspur | 7.3 ft | 0.3 ft above | 6.2 ft |
| Canal neighborhoodSan Rafael | 7.2 ft | 0.2 ft above | 6.2 ft |
| Bellam BoulevardSan Rafael | 7.2 ft | 0.2 ft above | 6.3 ft |
| East Fourth StreetSan Rafael | 8.9 ft | 1.9 ft above | 8.4 ft |
| Loch LomondSan Rafael | 9.7 ft | 2.7 ft above | 7.8 ft |
| McInnis ParkSan Rafael | 11.6 ft | 4.6 ft above | 8.9 ft |
| Bel Marin KeysNovato | 9.4 ft | 2.4 ft above | 6.8 ft |
| SeadriftStinson Beach | 10.3 ft | 3.3 ft above | 8.4 ft |
| Wharf RoadBolinas | 9.1 ft | 2.1 ft above | 7.8 ft |
| Inverness waterfrontInverness | 9.3 ft | 2.3 ft above | 6.6 ft |
| MarshallMarshall | 12.2 ft | 5.2 ft above | 9.0 ft |
Heights in feet above MLLW. Low ground is the middle height of the ground there that ordinary high tides do not cover. King tide from NOAA's Sausalito predictions; north bay tides run a little higher. Tap a place to see it on the map.
How the Simulation Works
The slider sets one still water level across the whole county. Every low spot that open water can reach at that level turns blue, and the shade shows how deep it would be. Water only gets behind a levee, a road berm or a seawall once it is higher than the lowest point on top of it. That is why Bel Marin Keys and the diked fields near Novato stay dry for a long time and then fill all at once, even though much of that land sits below sea level.
Tide heights in Marin are measured from mean lower low water (MLLW), the average of each day's lowest tide. At the Golden Gate gauge MLLW sits 0.06 ft below NAVD88, the survey datum the elevation data uses, so the two scales almost match. The level you set is the height a tide table or the NOAA gauge would show. Tides along the north bay shore run a few tenths of a foot higher than at the Golden Gate, so a given tide reaches a bit further in San Rafael and Novato than the same number does in Sausalito.
What the Map Leaves Out
A real high tide only lasts an hour or two. Water squeezing through a narrow channel or under a road may not fill a whole basin before it drops again, so the map can show more flooding than a short peak would cause. Waves, storm runoff from creeks and rain falling on the low ground are not in the model either, and in a winter storm those can flood streets the tide alone would not reach. Tide gates, pumps and walls thinner than the 4 meter elevation grid are missing too. Treat the map as a guide to which areas sit low and how they connect to the bay, and check the king tide dates and NOAA's live readings when water is actually rising.
Flood Simulation Questions
How does the Marin flood simulation work?
You pick a still water level and the map fills every low spot that open water can reach at that level. Ground behind a levee, a road berm or a seawall stays dry until the water is higher than the lowest point on that barrier. Elevation comes from USGS lidar on a grid of about 4 meters.
What tide height floods Marin?
Low parts of the Marin bay shore, like the Manzanita lot by Highway 101 and Shoreline Highway, start to take water during king tides around 7 ft above MLLW at the Golden Gate. Set the slider to 7 or 7.5 ft and look at Mill Valley, Corte Madera and the San Rafael Canal to see what that level reaches on the model.
What is the difference between MLLW and NAVD88?
MLLW is the average of the lowest low tide each day, and tide tables measure from it. NAVD88 is the national land survey datum that elevation maps use. At the Golden Gate gauge the two sit 0.06 ft apart, so in Marin a tide height and a land elevation in feet line up almost one for one.
Why does water sometimes flood less than the map shows?
The map treats water as level and connected everywhere at once. A real tide only stays high for an hour or two, so water pushing through a narrow gap or a culvert may not fill a whole basin before the tide drops. Tide gates, pumps and walls narrower than the elevation grid are also not in the model.