Three Forks water exceeds federal arsenic levels

One well found to have levels six times EPA guidelines

THREE FORKS—Recent water samples taken in Three Forks showed that arsenic levels were more than six times the recommended federal limit in one of the four wells that feed the town’s distribution system, according to information from the Gallatin City-County Health Department. 

Arsenic, which naturally occurs in groundwater in trace amounts, was measured at 67 parts per billion (ppb) when those samples were analyzed. The U.S. Environmental Protection Agency (EPA) set a maximum contaminant level (MCL) of 10 ppb. The other three wells in Three Forks’ municipal system all tested well below the MCL. At this time last year, all four wells were operating below the federally recommended level of arsenic.

The elevated arsenic levels were detected by routine testing in January, but the wells had not been tested since last March, when the city ordinarily conducts its annual tests. That means it is uncertain when the arsenic levels began to rise during the past 10 months.

Well No. 2, the well with the elevated arsenic levels, was immediately shut down and will remain so until the arsenic level is reduced, though it is uncertain how long that will take. According to the City of Three Forks, the treatment plant for Well 2 failed, and has also been shut down until the impurity-reducing media can be renewed.

“It is a high-arsenic producing well anyway, and we have a treatment plant that addresses that particular well,” says Crystal Turner, Three Forks city clerk. That plant has a filtering agent that pulls arsenic, iron and other impurities out of the water, but that filtering media was saturated, which is why the arsenic levels rose.

During and after its shutdown, that well will also be monitored and tested quarterly, rather than the requisite annual testing for arsenic. 

When the Three Forks municipal water system first went online it was tested more frequently, and when consistently favorable results came back testing was reduced to quarterly, then annually, which is the DEQ requirement. The public works department for the city voluntarily decided to go back to quarterly testing to monitor the quality of Well 2’s water more closely.

The Gallatin Local Water Quality District is also recommending that residents of Gallatin County who live west of the Gallatin River and who have private wells get their water tested to ensure domestic levels do not exceed the MCL. There are no laws that require domestic water testing, so if levels were high, they may not be noticed without the homeowner choosing to test their water supply.  

“The recent results in Three Forks serve as a good reminder to those who do have private wells, where there are no testing requirements, to test your well if you haven’t done so and to take protective measures to keep yourself and your family safe,” says Tammy Swinney, director of Gallatin County’s Local Water Quality District.

Long term exposure to high levels of arsenic, a proven carcinogen, can cause damage to the neurological, respiratory, cardiovascular and gastrointestinal systems, as well as skin lesions and bladder, lung and skin cancer. Young children are more susceptible to arsenic poisoning because of their lower weight and often weaker immune systems than adults. When the City of Three Forks is able to purchase and install a new filtration media in the treatment plant for Well 2, arsenic levels are expected to quickly drop back to below the MCL.

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