Coliform levels drop in Fremont Lake


Coliform levels drop in Fremont Lake

PINEDALE – A “fascinating mystery” that drove up fecal coliform levels in Fremont Lake from Aug. 1 to Aug. 9 seems to have just as mysteriously fixed itself. Tests taken Friday, Aug. 17, measured less than 1 colony-forming unit, down from the 716 measured on Aug. 3.

The results fall well below the 20 FCU allowed by the Environmental Protection Agency to maintain the town’s non-filtered water system.

In addition, tests sent to a lab to determine the species contributing the contamination were “indeterminate,” and based on the markers, might not have been fecal coliform.

Recent routine tests of Pinedale’s drinking water source, Fremont Lake, revealed something never before experienced – high amounts of fecal coliform in the lake.

Currently, water from Fremont Lake is gravity-fed to the Pinedale water treatment facility, where it is treated with chlorine and an ultraviolet system. The water is not filtered to remove larger particles. However, the chlorine and ultraviolet treatments kill the fecal coliform.

The Environmental Protection Agency requires routine samples from an open source, like Fremont Lake, to have fewer than 20 FCU per sample. Fecal coliform is a bacteria found in the intestines of warm-blooded animals. Tests are also done for giardia and Cryptosporidium parasites. A water source may not exceed the standards any more than five times in a six-month period or it may no longer be certified as a non-filtration system.

Fremont Lake’s pristine waters have always met those criteria.

Spencer Hartman, water and sewer supervisor for Pinedale, reported during the Aug. 13 town council meeting that changed in August.

On July 25, tests showed the water tested positive for 3 FCU, on July 31 that had jumped to 229.

In an email to Pinedale’s staff and council members, Mayor Matt Murdock called that “strike one of 5.” By Aug. 1 that number had grown to 618 CFU – strike 2 of 5. Only one day later on Aug. 2, the number hit a high of 716 CFU. That number did not count against the town, because samples were taken for the entire length of the lake in an attempt to find the source. However, later samples taken after that, while showing declines, still counted as strikes. By Aug. 9, the number had declined to 170, but still counted as strike four.

The next test was delayed to Friday, Aug. 17, the latest possible to see if the downward trend would bring numbers under the amounts allowed, to save the town from a fifth strike.

The lake continues to be clear of giardia and Cryptosporidium parasites.

By email, Murdock requested the council’s consensus to authorize expenditures to send samples to a specialized lab that could test DNA and determine what species of warm-blooded animal was producing the contamination and to expedite the results. The council followed up at its regular meeting, approving that $2,150 expenditure.

In a letter to the Department of Environmental Quality, sent Aug. 16 from Murdock and Hartman, the numbers were outlined. “After the spike the trend now seems to show the numbers dropping quickly as well,” the letter states.

“… We are moving forward to form a task force to understand what is happening in Fremont Lake and determine if this a long-term trend or a one-time event and identify any steps we can take to protect the lake and watershed from contamination,” the letter states. “I hope that the Wyoming DEQ would consider making one of their staff available to help us in this task force.”


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