USA - "potentially" dangerous chemical

PARLEY'S CANYON, Utah (ABC 4 News) - A potentially dangerous chemical spilled into Parley's Creek Friday morning. A tank with high concentrations of fluoride overflowed, dumping about 1,500 gallons into the creek feeding Sugarhouse Park and Tanner Park.
Tanner Park, a popular off-leash dog park, was not officially closed, but people are being told not to bring their animals there.
Fire fighters were stationed at the park entrance and warning signs were posted. All because of an overflowing tank of fluoride at Parley’s Water Treatment Plant. That chemical is now making its way downstream. Travis Kemp is a daily regular at Tanner Park, bringing his dogs to exercise. After hearing what happened he chose not to chance it. Kemp says, “We go down there to hang out in the water and swim and stuff so probably the reason I didn't go down there today.”
Fire and hazmat crews responded to the overflow just as the sun was coming up. They stopped the water with a damn and eventually pumped out the pool of contaminated water for testing. Initial tests results at Tanner Park were good. A representative with the Salt Lake City Department of Public Utilities said, “Nothing too hazardous at all… No fish killed down there at all.”

Still, officials are urging Utahns to keep themselves, and their pets, out of the water for the next several days. They say it will take two to five days for the fluoride to leave the creek water. Unfortunately, that means no splashing around Tanner or Sugarhouse Parks this holiday weekend.

The overflow was caused by a glitch in the transfer of the fluoride from what’s called a bulk tank to a day tank. Officials will be cycling large quantities of water through the creek for the next several days. They say that will help dilute the remaining fluoride and get it out of the water.