OSAKA -- Anyone for a dip? The Dotonbori River has been running through the center of Osaka's bustling Namba district since it was diverted as a waterway in the early 16th century. But the filth in the river makes the idea of holding a swimming tournament in it sound like a joke.

Yasuhiro Suchi, however, is dead serious about doing just that. Even more surprising is Suchi's plan to use pearl-producing shellfish to help him pull the event off.

"I wanted to organize an event to help clean the water in Osaka," said Suchi, 54, representative of the citizens' group Furusato Yume Zukuri Association, or roughly, "the association of dream creation in your hometown."

The polluted river was last in the spotlight when delirious baseball fans jumped in after their team won a big game.

Although Osaka is dubbed the City of Water, few people here pay attention to the quality, he said, adding, "I hope people will become more concerned with rivers and water" if a swimming match is held.

The swim meet will start at 4 p.m. on Aug. 8, 2004, on a 150-meter stretch of the river between Ebisubashi Bridge and Dotonboribashi Bridge.

The date was chosen as a reminder of "808 bridges," an Edo Period reference to the large number of bridges in Osaka, similar to the "808 towns" of Tokyo, he said.

Suchi began his work with the group in 1987. His job, running a pub, got him interested in water purity because quality sake requires good water.

Although the Dotonbori is now cleaner than it was 10 years ago, it is hardly swimable, a city official said.

The water quality of the river passes the environmental standard for sustaining life, but as it is probably full of bacillus coli, the official said, the water would not pass standards to allow swimming.

Well aware of that, Suchi hit on an idea that would simultaneously draw attention to the river and aid in its cleanup. Since the beginning of the year, the association has been inviting people to purchase pearls to be cultivated in the Dotonbori.

Over the next four years, pearls will be grown in hundreds of "ikecho-gai," a bivalve from Lake Biwa in Shiga Prefecture that produces pearls in fresh water. The shellfish can filter as much as 200 liters of water a day.

The cultivation of the shellfish and their pearls is scheduled to begin in May and 800 people have already signed up for the 5,000 yen purchase, according to Suchi.

"By paying money for their own pearls being grown in the Dotonbori, the owners care for the river and, hopefully, the water environment in general," Suchi said. "Because the pearls take four years to grow, the owner's interest in the water environment will last just as long, I hope."

In cooperation with a pearl cultivation firm near Lake Biwa, Suchi tested the shellfish cultivation in the Dotonbori from August to October, the hardest time for the shellfish to survive, because the river's water quality is at its worst due to the weather.

Since the test proved successful, Suchi is confident of the potential cleansing effect on the waterway. But he is aware that shellfish cultivation alone can not clean all the water in Osaka.

"I know it's impossible to make the river crystal clear, as it is connected to other rivers and Osaka Bay," he said. "The swim meet and pearl cultivation are only tools to raise the issue and draw people closer to the water.

"Water and rivers are Osaka's natural assets, but nobody is trying to protect these assets or upgrade their value. The water has been polluted over the last 40 years, so we should take as much time to restore it."