North Carolina's beaches cleaner than most, Noble says

Dr. Rachel Noble

The water quality at North Carolina’s beaches is better than that of most of the mid-Atlantic states. In fact, the state’s eight million annual coastal visitors enjoy some of the cleanest waters in the country, said Rachel Noble, PhD, associate professor of environmental sciences and engineering at UNC Gillings School of Global Public Health and of marine sciences in UNC College of Arts and Sciences.

At least until it rains.

During major storms, rainwater can pollute the ocean after it rushes across roads and sidewalks, acquiring chemical contaminants and microbes. As the rain washes over parking lots at beach-access points, it can pick up feces from seabirds that congregate there. And because eastern North Carolina is generally flat, standing water can mix with sewage treatment systems. That dirty water can make the ocean temporarily unhealthy for swimming, Noble said.

Noble said swimmers should avoid the ocean for 48 to 72 hours after a major rainfall, which she defined as being one-half inch or more.

“If there’s standing water still in the street, that is a good indication that you could be swimming in stormwater,” she said.

To improve safety for swimmers, Noble developed rapid water-quality tests for E. coli and Enterococcus, two types of bacteria that are used to test water safety. Her tests provide results in two hours or less, much faster than the 18 to 24 hours for methods currently approved by the Environmental Protection Agency.

Noble said she hopes those tests eventually can be used to quickly alert swimmers of unhealthy water conditions.

“We’re aiming to actually provide a water-quality result the same day people are swimming,” she said. Noble said the EPA may approve such tests by 2012.

UNC Gillings School of Global Public Health contact: Ramona DuBose, director of communications, (919) 966-7467 or ramona_dubose@unc.edu.