I kept running into a flooded path

I run the Mill Valley to Sausalito path most weeks. This fall I kept reaching Bothin Marsh to find it under water, with no good way to know beforehand.

In late October 2026 the king tides closed Miller Ave by Tam High day after day, flooded Hwy 1 at Manzanita, and put the path under water again. The tide tables said one thing, the water said another.

So I built the thing I wanted: a plain answer to "will it be flooded when I get there?" for the spots I actually use.

What it does

• It takes NOAA's tide table for San Francisco and shifts it by how far the real water has been running above or below it over the last 12 hours. That shift fades toward the weekly average over three days.
• Each spot has a water level where it starts to get wet, learned from past closures and from what I have seen on my runs. Each spot also floods a little after the San Francisco peak and drains later, so the timing is shifted too.
• It tells you Dry, Water possible, Flooded, Likely closed or Draining for each spot, for right now or for when you plan to go, with one line of advice for walking, biking or driving.
• The depth is a rough guess, given as a wide range: how far the forecast water is above the level where that spot starts to get wet.

What it does not do

• It does not know about official closures. Police, Caltrans and barricades always win over this site.
• It does not model rain, storm drains or creek flow. Heavy rain at high tide can flood places earlier and deeper.
• It covers three spots for now: Miller Ave at Tam High, Hwy 1 at Manzanita, and the bike path through Bothin Marsh.
• It sends no alerts yet.

These are estimates. Never drive, bike or walk through floodwater. It is often deeper than it looks, and it is salt water.

Tell me when it is wrong

If the forecast missed, or you saw water somewhere it said Dry, I would love to hear about it: [email protected]. Every report makes the next forecast better.

Charles, Mill Valley