COLUMBIA, SC — After years of putting rat poison in storm drains to kill rodents, the city of Columbia has discontinued the practice because of concerns about water pollution.

The city’s extensive network of drainage pipes discharges stormwater to creeks that flow into rivers such as the Congaree. But a small community outcry erupted recently, prompting the city to reassess the practice of baiting storm drains with blocks of rat poison.

“The city will work to identify other methods that should be considered to control the rat population,’’ according to a news release issued Wednesday afternoon.

City officials say they have no evidence the practice has violated any environmental laws. They also said baiting drains with rat poison was done on a complaint basis and was not a routine practice.

But they conceded that using rat poison in drains was inconsistent with a campaign that discourages people from dumping anything in the stormwater drainage system to control water pollution.

Tracy Mitchell, the city’s stormwater manager, said she’d gotten calls from people asking why the city tells people not to dump leaves and pet waste into storm drains, but Columbia was putting poison in the drains.

Mitchell said she was not aware of the practice until receiving a complaint from a Columbia resident whose dog ate rat poison from a storm drain.

Another city division charged with controlling rat populations was hanging the bait from storm drain grates, city officials said.

“I was really concerned when that came up, especially when I found it was another city department,’’ she said. “That was not something we maybe communicated as effectively as we should have on.’’

Congaree Riverkeeper Bill Stangler said he’s glad the city will stop the practice because “anytime you introduce a poison into water that is going to streams or creeks is clearly an issue.’’

Columbia’s rivers are natural amenities that are increasingly attracting kayakers and anglers — and that interest has put an increased focus on keeping them clean.

Even so, city officials said they’re in a tough position because the public doesn’t want rats crawling out of storm drains.

“We would not be applying it if there weren’t a problem at all,’’ said Missy Gentry, an assistant Columbia city manager. “It’s not like there is an infestation that is out of control by any means. Myself, I see one mouse and there’s a problem to me. One constitutes a problem to many people.’’

For now, Columbia will continue to use rat poison in its sewer system to kill rodents, but officials say that won’t threaten the public or water quality because wastewater does not flow directly into rivers. Everything goes through the city sewage treatment plant before being released to the Congaree.

It was not immediately known if the city’s treatment plant is set up to filter out rat poisons. The city will also monitor the rat population in the storm drain system to determine its next step.

Greg Kail, a spokesman for the American Waterworks Association in Denver, said he was unaware of rat poison being used widely in sewer or stormwater systems.