UPDATED 03/31/11 12:16 p.m.

CHICAGO (CBS) — A new regulation takes effect in Chicago Thursday, which critics say might hold up traffic in the Gold Coast and on the Magnificent Mile on account of horse carriages.

As WBBM Newsradio 780’s Mike Krauser reports the new rule calls for driver to stop and wash the street whenever a horse urinates in the roadway.

LISTEN: Newsradio 780’s Mike Krauser reports

The Chicago Sun-Times’ Fran Spielman reports the new rule came after Ald. Brendan Reilly (42nd) received repeated complaints about the lingering odor of horse urine in the quiet, affluent residential districts of the Gold Coast.

The rule requires horse urine to be “diluted with a deodorizing, non-toxic liquid” right away, the Sun-Times reported.

Speaking to CBS 2 Thursday, Reilly said the greatest problem that city crews have had to clean up the horse urine at taxpayer expense.

“The real issue here is that city tax dollars are being used here to clean up after the horses. I think that’s a terrible use of tax dollars,” Reilly told CBS 2. “Every other city requires drivers to clean up after their horses. City crews shouldn’t be dispatched to remove the stink.”

As it is, horses are required to wear diapers, as a result of a long and ultimately successful crusade by Reilly’s successor, former Ald. Burton Natarus. But the diapers only collect feces; the horses still urinate directly onto the pavement.

Carriage operators say the new rule could cause numerous problems.

“It’s unsafe and unrealistic,” said Dan Sampson, owner and president of The Noble Horse, which runs carriages on North Michigan Avenue.

“They are requiring the carriage drivers to stop their horse, after the horse urinates and either lean over or get off the carriage, and pour some material on the urine spot,” he said. “Carriage drivers are forbidden to get off the carriage by insurance reasons while there are passengers.”

The horses usually stop to urinate, and that could cause traffic jams, Sampson said.

“Imagine 9 o’clock Saturday night, Michigan Avenue and Superior Street,” he said. “A horse urinates at a traffic light. A driver gets off and bottles up traffic for three or four blocks while he pours that material on.”

Debbie Hay of Antique Coach and Carriage says the new policy could also make for a dangerous situation. The horse know to go on a green light, and the absence of the carriage driver wouldn’t necessarily stop them, she said.

“You may have passengers in your vehicle and your horse may see the green light turn green,” she said. “You’ve got to hold on to your horse and do this at the same time to make it safe.”

Carriage owners also argue that the rule should also apply to dogs, the Sun-Times reported.