Is your beach contaminated?

• Position: Your Life

Nothing will ruin a day at the beach like a sign in the sand that reads, "Warning: Contaminated Water. Unsafe for Swimming or Contact," because of the presence of fecal bacteria. According to Alexandria B. Boehm, the Clare Boothe Luce Assistant Professor of Civil and Environmental Engineering at Stanford (Calif.) University, "There are many factors that can influence the concentration of bacteria in a sample of water. A lot of water sampling is done once a day, but there usually is a one- to four-day delay between the time a sample is taken and testing results are known.... [A] lot of pollution events last just one day or one hour, so the problem is likely to have passed by the time a warning sign is posted."

The result is that people may be barred from swimming at beaches that are actually clean, while contaminated beaches may be inadvertently kept open, exposing swimmers, snorklers, and surfers to a wide range of illnesses, some producing mild symptoms (such as chills, fevers, and upset stomachs) and some that are potentially lethal (including hepatitis and meningitis). Beach closures also can have a serious economic impact on restaurants, shops, and other...