TRAVERSE CITY, Mich. -- High bacteria levels in Lake Michigan prompted officials to close beaches or issue no-swimming advisories 599 times this year, the highest number on record, an advocacy group says.
The closures - up from 388 last year - were due, in part, because local governments are getting better at measuring bacteria levels, said Laurel O'Sullivan, spokeswoman for The Lake Michigan Federation.
Human and animal waste are the biggest causes of bacterial pollution. Waste flows into the lake when heavy rain causes sewage and runoff to bypass treatment plants.
The federation has tallied closings since 1996 by surveying officials in the four states bordering the lake.
Illinois led the way with 339 closures, up from 119 last year; Wisconsin had 154, down from 246 in 2000; Indiana rose from 15 closures last year to 92; and Michigan had 14, up from eight last year.
A closure is defined as a 24-hour period during which people are ordered or advised not to swim.