A recent drinking water standard violation in Dickinson was likely the result of a pre-treatment or lime softener added to the sample site, city and health officials say.
The City of Dickinson sent out a notice to customers earlier this month informing them that coliform bacteria -- commonly found in topsoil -- had been detected in two routine water samples, one more than the standard one sample per month.
The violation was not an emergency, and was not part of a continued problem, said Gary Zuroff, the city's public works director.
"It was isolated to only one service line in one sampling location," Zuroff said. "The pre-treatment was there before we sampled. It was just from their own service line."
He didn't specify which sample location was found to have coliform bacteria, but noted that the commercial building was notified.
"We didn't find bacteria in any other subsequent testing, and haven't since we found the sampling," he said.
Under the Environmental Protection Agency's Total Coliform Rule, the city takes 20 water samples each month from specific sites across the grid. If a sample shows the presence of coliform bacteria, repeat samples are taken at and around the site. The rule has been in place since 1989.
Southwest District Health environmental health practitioner Rex Herring said it's uncommon for officials to find bad samples in Dickinson.
"Most of the time, the City of Dickinson's water checks out very good, so when we find something, it's normally the sampling site, and not the water," he said.
He said other faucets in the particular building where a positive sample was found showed no signs of coliform contamination.
"If there would have been a problem in the city's water system itself, it would have shown up in any of the follow-up tests up and downstream from the site," he said.
Zuroff said the city and the health department decided the contaminated site is "not indicative of the watering system" and will no longer be a sampling site.