Drake Avenue and Donahue Street
The corner the model's readouts follow, by the Gateway at the way into town, where runoff that cannot get into the Drake pipe ends up standing. The county's plan puts a bigger pipe and more inlets here.
3D model
Thirty days of tide and rain, and one pipe out
A month of Richardson Bay tide and six storms, with the neighborhood on top: the streets, the Gateway center, and the Highway 101 crossing with its single underneath. Drag to turn it, or use the “Look from” buttons to jump to a place. Press Play and watch the water rise behind the highway embankment.
It opens paused at Day 1, 12:00 AM, with a 10-year storm and none of the three measures on. Play runs the month and stops at its end, Day 30, 11:55 PM; Reset starts it over. The measures, under “What if…”, are (ground that soaks up rain instead of piping it away), a pump station and a gate that seals. New to the bowl, the culvert and the gate? Start with how the flooding works, which explains the three levers. The home page has the same scene with the bay's real level right now.
Look from…
Show…
Swings round to the view from over the bay, where the ridge closes around the flat on three sides, so the shape of the place stands out; press it again to go back.
Not a storm that comes every 10 years — one with about a 1 in 10 chance of happening in any year. Over thirty years that is roughly a 96 in 100 chance of seeing it at least once. Depths are NOAA Atlas 14 for this watershed.
What if…
Sponge measures — more ground that soaks up rain where it falls (gardens, porous paving, a park that can flood) and room to hold rain back before it reaches the streets; in this model, a little less runoff and about 1.2 million gallons (4,500 m³) held back. One oddity: in the model's 2-year storm they put about half an hour of water over Drake & Donahue, where none stands without them. Sources & limits explains why. Pump station — a pump lifting 50 cubic feet of water a second, about 22,000 gallons a minute, over the gate into the bay. Gate seals properly — the gate under the highway stops leaking bay water back into the bowl.
None of these is a promise about what will be built; they are three things to try. The pump station is the size the county's 2025 stormwater plan proposes.
Day 1. Water below street level at Drake & Donahue.
Bay level
+7.6 ft
King tide (very high) · +2.32 m
Water in the bowl
+2.1 ft
Drake & Donahue floods once this passes +8.3 ft (+2.53 m)
Gate under the highway
Shut, but leaking bay water in
Rain now: 0.00 in/hr
Buildings taking water
—
counted once the 3D view is built
Month so far
0.0 hours under water
at Drake & Donahue, 0.0 days in
Water leaves through one 72 by 38 inch culvert opening — about 19 square feet. When the bay stands higher than the bowl, it leaves through nothing at all.
Map data © OpenStreetMap contributors, ODbL: the streets, Highway 101 and its ramps, sidewalks, parking aisles, bus stops, and the floating homes and their docks. Via the Overture Maps Foundation: parks, fields, trails and natural cover such as woods, scrub and beaches, Golden Gate Village's building footprints, and the Marin Gateway's buildings, parking areas, walls, hydrants, power poles, bus stops and charging points (OpenStreetMap contributors, ODbL). Also via Overture: the piers and floats of Tiburon and Angel Island, and the buildings there and on the freeway's bay side that the lidar does not have (OpenStreetMap contributors and Microsoft, ODbL; Esri Community Maps, CC BY 4.0). USGS, public domain: 3DEP lidar for the ground, roofs and trees; 3DEP 1/3 arc-second elevation for the ground at the model's edge and the shoreline out to the horizon; the National Transportation Dataset for roads past the OpenStreetMap area. Angel Island's tree cover past the lidar: © ESA WorldCover project 2021 / Contains modified Copernicus Sentinel data (2021) processed by ESA WorldCover consortium, CC BY 4.0.
Your street
What this says about your street, and what it cannot
The street readouts follow one corner: Drake Avenue at Donahue Street, by the Gateway near the freeway. In the model's month, water goes over the street there from the 10-year storm up. In its 100-year storm, with none of the measures on, the water stands there for about 4 hours, up to about 20 inches deep. Lower spots, like Donahue beside it and the freeway off-ramp, go under earlier and stay under longer: about 5 and 7 hours in that storm. Smaller storms can still leave water standing there. The county's plan says runoff cannot get into the Drake pipe fast enough, and the model leaves that out. It does not know your street or your home, and what you have seen there beats anything here.
The real place
What the model is a diagram of
In the bowl, the scene is mostly stand-in buildings on measured ground: the shape of the problem, not the look of the place. Here are the same spots in Google Street View.
Nothing from Google loads until you click. This site runs no analytics or trackers and serves its own fonts. Street View is Google's imagery, from a date they chose, with no flood drawn on it.
Donahue Street, toward the highway
The corridor the water comes up. The ground here is about +10 ft (2.9 m), higher than the Drake Avenue corner by the Gateway, about 300 m ahead.
Marin Gateway
A paved parking lot of several acres between the corner and the pond, draining to the pond behind it.
Toward the pond and the crossing
The three-acre tidal marsh that holds stormwater before it leaves, and the Highway 101 embankment beyond it. The sluice gate and the 72 by 38 inch culvert are at the far side.
Graham Park
Where the hill gives out and the flat begins, at about +30 ft (9.2 m). The site the vision page suggests as a floodable lawn.
Drake Avenue, up the hill
Where Drake Avenue climbs out of the flat, at about +24 ft (7.3 m), looking out over it.