More than 3 million tourists descend on this town of 57,740 every year, said Judy Young, Convention and Visitors Bureau director, most of them in the 99-day window that stretches from Memorial Day to Labor Day. Merchants will be happy, Young said, since those visitors pump $469 million into the local economy, filling most of the town's 22,000 hotel and motel rooms. In the past, the rivers were full of tubers misbehaving, with the most common crimes being public intoxication, minors in possession of alcohol, trespassers and numerous cases of public indecency. “The size of the crowds have increased every year,” said Sgt. Pete Snyder, head of the city's designated river patrol, known officially as the Community Response Team, but bad behavior has been on the decline.