Authorities say nearly 2,000 gallons of the chemical spilled into the creek Friday morning.

Four Hazmat teams worked to keep the fluoride from flowing beyond the dog park at the base of Parleys Canyon by using dikes and absorbent sponges, said Unified Fire Authority spokesman Travis Hanberg.

The fluoride tank at the Mountain Dell water treatment plant overflowed sometime between 1 a.m. and 5 a.m. About 1,500 to 2,000 gallons of flouride spilled into the creek, Hanberg said.

"The major concern is the pH change, which would make it a pretty severe skin irritant," Hanberg said.

By 8 a.m., parts of the creek were registering a normal 7 pH, Hanberg said. Still, authorities want to keep people and pets out of the water.

Hanberg said the spill will likely kill fish in the creek and sicken deer and other animals that drink from it.

Fluoride is added to drinking water and other products, including toothpaste, to strengthen teeth.