Testing the Waters

Harmful bacteria found at Wisconsin's Great Lakes beaches

Last summer, for the first time ever, several Door County beaches were closed because of poor water quality. The “No Swimming” signs may have been disappointing to vacationers and tourist-dependent businesses, but they do not necessarily signal deteriorating water quality, according to UW Sea Grant Water Quality Specialist Vicky Harris.

“Even though it’s a nuisance, beach closings mean the public is better informed about potential health risks,” Harris said.

In Wisconsin and many other states, local agencies that test beach water are finding E. coli bacteria, which is found in human and wildlife waste and indicates the probable presence of other disease-causing organisms.

In Door County, increased testing this summer was prompted by an outbreak of illness among 70 people who swam at Nicolet Beach in Peninsula State Park. The testing led to 23 days during which at least one of the county’s beaches was closed, according to Door County Sanitarian John Teichtler. Previously, those waters were tested only when someone complained, and that was rare, Teichtler said.

In other communities along Lake Michigan—and throughout the country—more frequent beach water testing was prompted by the federal BEACH Act of 2000, an amendment to the Clean Water Act that requires all states to meet Environmental Protection Agency monitoring standards to receive federal funding for water quality testing. The act also requires states to meet EPA monitoring and reporting standards by 2004.

No one knows for certain where the bacteria in Door County came from, but the many possible sources include sewage system overflows, leaking septic systems, boaters who dump human waste overboard, and rainwater that washes droppings from gulls and geese into the water, according to Harris.

The sources of pathogens were unknown for more than half of all reported beach closings in the United States in 2001, according to the Twelfth Annual Beach Report issued this year by the Natural Resources Defense Council. That stands to reason, according to Sandra McLellan, a geneticist at the UW-Milwaukee Great Lakes WATER Institute who is studying ways to use DNA fingerprinting to trace the origins of pathogens in beach water.

“Measuring bacteria concentrations is far easier than determining their source,” McLellan said.

Unlike many smaller communities along Lake Michigan, the city of Milwaukee has been testing water at its beaches for several decades, according to Mary Ellen Bruesch of the City of Milwaukee Health Department.

“Those data do not provide any evidence that water quality is getting worse,” Bruesch said.

Fecal contamination is not a problem at Wisconsin’s Lake Superior beaches, according to public health officials in the four counties bordering the lake. The colder water limits bacteria growth at those beaches, officials said.

The Wisconsin Department of Natural Resources has received a grant from the EPA to work with local agencies, scientists and environmental groups to develop improved public notification of poor beach water quality.

The increased attention in recent years to the effects of storm water runoff on beach water quality is raising questions about other effects that runoff might have, McLellan said. “We’re measuring fecal contamination now, but that raises the question of what else is traveling in that water,” she said.

 “That hasn’t really been studied carefully.”

- John Karl

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Last updated 20 December 2002 by Karl
All contents copyright 2000 University of Wisconsin Sea Grant Institute

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