Although she spends major time entering data on her computer and assaying samples in her lab, it really helps to get out to the beach.
So says Alexandria Boehm, an assistant professor of civil and environmental engineering and a Hawaiian-bred surfing aficionado. Two summers ago, Boehm, a specialist in coastal water quality who was then on the UC-Irvine faculty, supervised some 50 students on a three-week, 24-hour-a-day study of one of her favorite surfing spots in Southern California—Huntington Beach—which had been closed for two months in the summer of 1999. Boehm’s team dug through data for more than 100,000 surf-zone water samples dating back to 1958 and also took frequent samples of ankle-depth ocean water in 500-milliliter plastic bottles.
Her conclusion: many historical episodes of contamination can be traced to raw sewage spills, stormwater runoff or nuisance runoff. More surprising? Water quality can also be affected by sunlight, rainfall and patterns of the lunar cycle, with harmful bacteria at their highest levels during the rainiest months and at midnight under a full or new moon.
Boehm says her studies, which have been published in the prestigious journal Environmental Science & Technology, also tell her that decisions to close beaches shouldn’t be based on once-a-day, early-morning samplings of water. And if you don’t trust beach-closing signs, “you can use the rule, ‘Don’t go in the water during the new and full moons,’” she says.
In her first year at Stanford, Boehm has begun to look at historical data for Santa Cruz beaches that date back to 1987. She’d also like to design some field projects in San Francisco Bay for her students. “I miss the ocean,” she says, almost wistfully. Especially Flat Island, off Oahu’s Kailua coast. “The waves break right next to the island,” she remembers, “and everyone out there kind of knows each other.” What a lab.
