Running Aground

There are two types of sailors on San Francisco Bay: those who have run aground, and those who will admit it. It’s not that Bay sailors are inept; Bay waters are shallow.

By Scott Alumbaugh
Published: February, 2007 

In fact, the average depth of San Francisco Bay is only 12-14 feet. Before the Gold Rush, the average depth of the Bay was 42 feet. So, what happened?

The entire San Francisco Bay-Delta Estuary encompasses 1,600 square miles, ranging from the salty waters of the Bay to the brackish waters of the Sacramento-San Joaquin Delta. The Estuary’s upstream watershed drains more than 40 percent of California’s land mass, including the freshwater streams of the Sierra Nevada.

Most of the mud in San Francisco Bay came from the Sierra Nevada mountains. During the Gold Rush, mining companies used high-pressure water to blast away huge mountains to search for gold. The sediment loosened by hydraulic mining washed into the rivers and filtered downstream, depositing tons of sediment in the Bay.

And not only has the Bay become shallow, it has also shrunk by a third in the last 150 years.

Before about 1860, most bay shores contained extensive wetlands that graded from freshwater wetlands to salt marsh and then tidal mudflat. A deep channel ran through the center of the Bay, following the ancient river valley. Starting in the early 1900s, as the Bay silted up, the Army Corps of Engineers started dredging channels to keep the waters deep enough for commercial vessels. A lot of the sediment they dredged up was dumped in bay shallows. The most visible example of that practice is Treasure Island, built from Bay sediment for the 1939 Golden Gate International Exhibition.

It could have been even worse.

In the mid-40’s, a schoolteacher named John Reber put forth a plan that envisioned two low barriers across the San Francisco and San Pablo Bays. The barriers would support rail and highway traffic and would create two vast freshwater lakes, supplying irrigation water to farms. Between the lakes, the Reber Plan proposed the reclamation of 20,000 acres of land that would be crossed by a freshwater channel.

In 1953, the Army Corps of Engineers constructed the Bay Model in Sausalito to test the idea. Happily, the barriers failed to survive this critical study.

So, thankfully, we still have salt water to sail in, a damaged but still vital estuarial system, and efforts like The Bay Institute working to restore the Bay.

But, we still have all that mud. And we still have to keep our boats out of it, or get them out if they get stuck. What to do?

Smart Bay sailors keep nautical charts handy. Because, really, look around; can you tell how deep the water is just by looking at it? They also consult a tide chart, because occasionally the water is even shallower than the depths stated on the nautical chart.

Even still, the best of us has been stuck. I have sunk my keel in the muck under the docks in front of Sam’s Anchor Café in Tiburon, and have woken up aground after overnighting at anchor in Clipper Cove while teaching a Bareboat Chartering class.

If you do run aground, the good news is that it is most likely you struck mud, not rock, so at least you won’t sink. There are multiple ways to deal with grounding. You might try to get all of the weight over to one side of the boat to tilt the keel up; or start up the engine and try to back off; or row an anchor out, drop it overboard and use that to kedge off.

My favorite solution? Break out some food, get something to drink and get comfortable. The tide will come up again; it’s just a matter of time.