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Arrowhead Marsh, Born 1874?
Anthony Chabot liked to think of himself as a creator, and to be sure he was one of the prime builders of the East Bay's water system. But Christoper Richard suspects the "Water King" may also have played an inadvertent role in creating a popular wetland near the Oakland Airport.
While doing research on local watersheds for the Oakland Museum, Richard noticed that the marsh wasn't on the original 1850 U.S. Coastal Survey maps of San Leandro Bay. However, survey charts published in 1895 clearly showed the distinctive arrowhead shape pointing toward the east end of Alameda. A little historical investigation gave him a clue as to what might have happened.
In November 1874, Chabot was in the middle of constructing a 450 foot earthen dam across San Leandro Creek. Then a series of huge rainstorms hit, blowing out the 20 foot clay wall he had built. Richard theorizes that the estimated 20,000 cubic yards of clay was carried six miles down the bloated stream, creating a sandbar in the Bay. From there, organic and inorganic material began collecting, forming the 50 acre marsh.
Core sampling and other testing needs to be done before any conclusions can be reached, Richard says. He's only done "very rudimentary" field work so far, but hopes to do more sophisticated analyses soon.
"It's a testable idea," says wetland scientist Josh Collins of the S.F. Estuary Institute, adding that channelization patterns indicate the marsh probably was created by a "sudden localized event."
Could Arrowhead Marsh provide an example for modern day wetlands restorers? Richard thinks so. "Here's an area where man did nothing more than dump a bunch of dirt, then natural forces did their magic and made us a nice little marsh," he says. "We're probably better off following the lessons learned here - just dump the stuff and let nature define what the site's going to look like."
Contact: Christopher Richard (510) 238-2200
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