Oklahoma City, OK - Concerns are building in Piedmont after a family said they found dangerously high levels of chlorine in their tap water, which they think killed their fish.

The McNeelys built their koi pond more than a decade ago. It has become their place to relax, but Memorial Day weekend, they were shocked and saddened to find dozens of their fish dead.

About 25 fish were found floating atop the water right after the McNeelys topped off the pond using a nearby spout, part of their normal maintenance routine.

“The faucet was left on a little longer than it should have been, but we’ve done it before,” said Brenda McNeely.

The family immediately suspected a chemical imbalance.

“I was just floored that there was enough chlorine in the water that it could kill these fish that have been around for so long that fast,” said the McNeelys’ daughter Christy Brown.

They said the tap water has smelled of chlorine for years, ever since Piedmont started pumping water from Lake Hefner. When the water started bleaching their clothes, they switched to bottled water for drinking and cooking and converted the pool to salt water.

The mass death of their fish, however, finally pushed them to test the taps for themselves. Brown, who has a biology degree with an emphasis in immunology and oncology, used a pool test kit to show how much chlorine was in the water Sunday.

She said that the yellower the water is during the test, the higher the chlorine level. The test came back with a much darker yellow than the five parts per million listed as the maximum on the chart.

“I would guess nine to 11 parts per million,” Brown says, “and tests show that tap water should never be above four parts per million, and that’s a drastic chemical increase.”

Oklahoma City's most recent tests of Lake Hefner show the chlorine averaged just below the safe level in both 2014 and 2015, but peaked higher than the EPA recommended four parts per million both years. Daily level counts are unavailable, and the public works supervisor for Piedmont was unaware of any chemicals added to the source Memorial Day weekend.

“We trust that we’re being protected by those that are in positions of authority, and we just really trust that when we turn that faucet on it’s not going to be something that’s actually dangerous,” McNeely said.

Chlorine does eventually evaporate after it is introduced into water sources, but the McNeelys fear long-term effects on the community.

“I know we have to have our water sanitized,” said McNeely. “It wouldn’t be safe without it, but this is above and beyond.”

Piedmont city manager Jason Orr responded to News 9's request for water quality test results:

The City of Piedmont Public Works Department conducted numerous chlorine tests throughout the town Monday and found nothing abnormal or outside the standards of the Oklahoma Department of Environmental Quality. We will continue to monitor those levels to ensure we provide quality water to our community.