A fluoride tank overflowed at a treatment plant Friday, spurring a warning to stay out of a Salt Lake County creek this holiday weekend

The 1,500-gallon spill occurred at a water treatment plant west of Mountain Dell Reservoir and next to Parleys Creek. Utility workers were able to contain much of the chemical with sandbags and a makeshift earthen dam. But Salt Lake City’s utility service is advising people and pets to avoid the creek and the Jordan River until Wednesday. That’s due in part to the fluoride and in part to increased flows caused by a release of water from Mountain Dell Reservoir to flush the chemical from the creek.

Parleys Creek flows through Tanner Park, Sugar House Park, Hidden Hollow and drains into the Jordan River.

“We have no anticipation of any negative or harmful effects and the measures we are taking are precautionary because we don’t want to take a chance,” said Stephanie Duer, a spokeswoman for Salt Lake City Department of Public Utilities.

The fluoride concentration would not be fatal but could cause skin irritation, Duer said. Duer said a fish kill is possible but biologists and foresters have given her differing opinions on whether other serious harm could come to wildlife and dogs coming into contact with the spill.

Duer said the utility service is trying to determine what caused the fluoride to overflow.