No dirty water here: Charles River swim scheduled for Sunday

> A former bathhouse from 1898

By Beth Daley, Globe Staff

After two years of nail-biting that the Charles River would be too polluted to host an organized swim to celebrate its cleanliness, this year's swim is on - and there isn't a harmful bacterium in sight.

"It's going to be a great day for getting out in the Charles,'' said Ben Martens, Swimmable Charles Coordinator for The Charles River Conservancy, an advocacy group. The one-mile swim, which is sold-out, begins at 8 a.m. at the River Dock - near the Arthur Fiedler head statue by the Hatch Shell on Esplanade.

Once, the Charles River was packed with swimmers seeking relief from the heat. A series of bathhouses were built along the river in the late 1800s and early 1900s to urge people - many newly arrived immigrants - to dip in, clean off, and enjoy themselves.

It was hardy a pristine experience but swimming remained popular in the Charles until the 1950s, when people became more aware of the dangers of industrial waste and sewage that fouled the river, inspiring the Standells to write their 1960s hit song "Dirty Water." Since then, a multimillion-dollar cleanup has restored the river.

A long-term goal of river organizations is to get the river swimmable and two years ago, The Charles River Swimming Club planned an inaugural swim. Yet the race had to be canceled after state environmental and health officials discovered potent blooms of blue-green algae, which can be toxic to humans, in the river. Last year, race organizers moved up the swim, only to discover an unusually early bloom of the algae, also known as cyanobacteria.