One of Jacksonville's biggest birdbaths is due for a cleaning.

The duck pond water at Riverside Park has been clouded and smelly for years, a soup of feathers and droppings from colonies of ducks, swans, ibises, egrets and other creatures that crowd onto an island in the late 19th century park.

A project to clean the water by spreading floating trays of marsh plants last year helped, but the wildlife trampled the plants and ate them.

So the neighborhood's city councilman says it's time to just pump the pond dry and start over.

"What we realized was after 15 years plus of no treatment of the water, it has gotten to a point where it is not healthy," Michael Corrigan said.

Last month, he filed legislation to spend $100,000 to empty the pond, dredge drifts of sunken bird poop and refurbish work that was done on the pond's bottom in 1994.

The money would come from fines the city collects from air and water polluters and stashes in a trust fund for environmental improvements.

City officials say they need some way to clean the water, which is held in place by a liner and only leaves when hard rains fill the pond enough to empty into a drain that reaches the St. Johns River. While lots of ponds need maintenance to clean out silt or control plants, the stagnant, foul water in the duck pond represents an extreme.

"It's basically a large swimming pool. It's not a typical stormwater pond by any means," said Vince Seibold, chief of the city's Environmental Quality Division.

"But when it rains and it overflows, it does go into our stormwater system and ... into the river."

While the pond is pumped out, a foot-thick layer of sand spread on the bottom would be changed out, too.

A permanent fix is still needed, Corrigan said. He wants the city to try new ways to get the stagnant, algae-choked water moving.

Sprinklers for the park's landscaping might be able to use pond water instead of tapping into JEA lines, he said. That would save fresh water and in theory turn the park grounds into a filter system for anything in the water.

That could be a model to use at other ponds around town, Corrigan said.

But first people have to figure out if that's safe, said Seibold, who was asked by the city Environmental Protection Board to check with health department employees and state agencies about whether the water is suitable for lawn watering.

steve.patterson@jacksonville.com, (904) 359-4263