For the week of October 23 - 29, 2002

County’s groundwater tests clean of contamination

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By GREG MOORE
Express Staff Writer

Blaine County’s groundwater quality was given a clean bill of health last week following a study of 40 local wells.

Hydrologist Lee Brown presented his findings to the county commissioners during a meeting on Oct. 15. He said all but one of the wells tested clear of coliform bacteria, whose presence indicates fecal contamination, and that nitrate and chloride levels, also a good indicator of human activity, tested very low as well.

"The results were amazing to me in their benignness," Brown said.

The $5,000 study was conducted in mid-September on wells from North Fork to Carey.

Brown said that wells down-gradient from development were chosen for the study.

"All of these wells were selected in places where we expected to find trouble if it’s there," he said.

He said the results therefore indicate that the rest of the Big Wood Aquifer is probably free of contamination.

"Our drinking water is the most important part of our valley in terms of our health and safety," Commissioner Sarah Michael said in an interview. "Making sure we’re not impacting that is an important part of county policy."

Brown said the one well that tested high in coliform levels is a domestic well south of McHanville—an area where water quality has been problematic in the past.

"That 40^th well is truly a bad boy," he said.

He said the first test there measured 76 bacteria colonies, though a second measured only 26. However, one colony is the maximum for a well to be declared clean, he said. In a later interview, Brown said further tests will be done in about 10 days to determine whether the contamination there is in the groundwater or in the filtering system.

Groundwater contamination in that area has long been suspected to come from McHanville’s dense development and many septic systems. However, that’s never been proven.

"There’s something geologic going on there that nobody quite understands," Brown said. "There have been spotty results of contamination over a long period of time. What’s weird is that it’ll be there one test period and not the next."

He said a geologic study sufficient to clarify the situation would be very involved and expensive.

Brown recommended to the commissioners that county-wide well monitoring be done on an annual basis, at a cost of $1,500 to $2,000 per year.

Anyone seeking a building permit from the county must first obtain a sewage permit from South Central District Health, which prohibits septic systems on parcels of less than one acre. Beginning last summer, the Idaho Department of Environmental Quality directed the agency to require tests of the soil and groundwater under proposed subdivisions to determine the number of septic systems that can be supported and their optimum locations.

"The study will predict the movement of nutrients and pathogens in the groundwater," said South Central Environmental Health Specialist Bob Erickson.

Erickson said the district requires the studies on proposed subdivisions of 10 or more lots, and for any parcels where particular concerns exist. He said that when appropriate, study results will be used to require that lots with septic systems be larger than one acre, but never to reduce the one-acre minimum.

 

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