A report on Illinois beaches released today by the Natural Resources Defense Council suggests that the use of border collies to harass gulls has helped reduce water contamination levels at area beaches.



The annual NRDC assessment says the difference was most apparent at 57th Street and 63rd Street beaches, where the first use of collies in 2008 coincided with significantly smaller percentages of days on which water contamination exceed state standards.



What's more, the following year, when collies were not used, contimination levels climbed, and in 2010, when the collies were used again, levels fell again.



The dogs, who are trained to distinguish gulls from other varieties of birds, are used from dawn to dusk to chase away gulls, whose droppings contribute to E. Coli contamination, studies have shown. They are being used again this summer seven days a week at 63rd Street and on a part-time basis at 57th Street and South Shore, said Zvez Kubat, a Chicago Park District spokeswoman.



Overall, the report said, contamination levels at all the state's beaches -- defined as the percentage of beach-monitoring samples from Memorial Day to Labor Day that exceeded the state's daily maximum bacterial standard -- was about 14 percent, slightly lower than a year earlier.



According to the report, the beaches with the highest percent exceedance rates in 2010 were: