For Charles, a mile-swim marker

Decades after authorities banned bathing in the filthy Charles River, the state is considering whether to sanction a 1-mile swimming race in the once-degraded drink.

The event, proposed by a newly formed swim club, would mark a milestone in a 20-year, $4.5 billion cleanup, but there would be two key restrictions: The race can't be held within a few days of a rainstorm, and swimmers can't touch the toxic riverbed.

``I think the proposal looks terrific, and we'll certainly do our part to make it happen," said Stephen Burrington, commissioner of the state Department of Conservation and Recreation, which oversees events on the Charles. ``We're looking at it with a very receptive eye."

The proposal , subject to state approval, calls for an 8 a.m. start on Sept. 9 and would be limited to 100 swimmers, all of whom would have to be members of the US Masters Swimming Program. The race would probably start and finish at a refurbished dock near the Hatch Shell on the Esplanade.

Water quality in the Charles has improved significantly in recent years, but not enough for a return to general swimming. Burrington said it could be a decade before that occurs. The issue of heavy rain is important to the proposed race because bacteria levels are often very high after storms , as runoff from street drains overwhelms the sewage system .

``It's not perfect," said Frans Lawaetz, founder of the 20-member Charles River Swimming Club, which was started last year to encourage a return to river swimming. ``But this is something Boston can really be proud of."

Several other communities sponsor river races. Lowell has held a summertime 2-mile swim in the Merrimack River. New York has 11 river swims each summer, drawing a total of about 1,000 participants, said Faith Armonaitis, spokeswoman for the Manhattan Island Foundation.

The Charles swim would draw on qualified applicants from around the country and is not intended as a fund-raiser, said Lawaetz. The race course would be in water at least 8 feet deep. Scuba divers will inspect the course before the event to ensure that no debris protrudes from the riverbed along the area.

The race would be advertised on swimming and triathlon websites, and registrants would apply through Charlesriverswimmingclub.org .

The grunginess of the Charles was celebrated in ``Dirty Water," the Standells' 1966 garage-band classic ode, now an unofficial city anthem. There were at least five beaches along the river in Boston and Cambridge until the 1950s and early 1960s, when pools were built. Rowers from the 1960s recall a sheen of oil on the river's surface. Harvard crew coach Harry Parker said the water at the time also reeked from a slaughterhouse near the Arsenal Bridge. If athletes suffered a cut, they got a tetanus shot.

``It was awful," said Tom Tiffany, a coxswain for Harvard from 1967 to '71 and a coach on the Charles for many years since. ``There would be these rainbows of muck and horrible fumes, and it would make your eyes burn."

But the water quality has improved such that rowers have started jumping in after a hard practice, Parker said. The river's grade on an EPA report card rose from a D in 1995 to a B last year. Windsurfers recently started sailing just off the Esplanade -- despite occasional dunks -- even though swimming in the Charles is still prohibited.

Improvements are being designed to ease the rain runoff problem . With a recent settlement, authorities plan to divert excess runoff to the Deer Island Sewage Treatment Plant, cutting the discharge of dirty water from 200 million gallons a year to 8 million gallons by 2013.

Ridding the Charles of toxic sediment is trickier. The DCR warns fishermen not to eat their river catch because many of the fish are bottom feeders. The sediment sticks to the riverbed because the current is not fast enough to push it out to sea, said Renata von Tscharner, president of the Charles River Conservancy.

``We still don't know how we're going to deal with that," Burrington said.

The prospect of persuading racers to dip into the Charles is a less technical challenge. Lawaetz, 27, must convince prospective participants that the race is no publicity stunt, like the 1996 camera-ready dive into the murky deep by Governor William F. Weld, who was running for US Senate . To Lawaetz, a Virgin Islands native with no memory of the Charles in its disgusting years, the race is the start of a dream. One day, he hopes, happy summertime swimmers will splash in the Charles as he is crossing the Longfellow Bridge.

Lawaetz's proposal has persuaded a few onetime naysayers, including Harvard's Coach Parker. ``If someone had told me there would one day be a race, let's just say I'd be skeptical. But today I think it's a great idea," Parker said.

Lawaetz knows he will have a tougher sell with other people .

``When I tell people we want to have a swim race in the Charles," Lawaetz said, ``most of them look at me like I'm crazy."

Douglas Belkin can be reached at dbelkin@globe.com.