A study recently conducted by the Flathead Lake Biological Station detected pollution in shallow water wells in the Flathead Valley, but state and county officials stress that the valley’s main aquifer and deep water are safe.

The study analyzed samples for 17 shallow and susceptible wells in the Evergreen area between the Whitefish and Flathead rivers.

The wells are less than 31 feet deep and are known to be vulnerable to seepage from surface and ground sources, septic tank leakage and other pollution sources.

Joe Russell, Flathead County’s public health officer, said volatile organics were detected in some of the wells and pharmaceutical and personal-care products were found in four wells.

Russell said that it is not uncommon for unprotected wells — especially shallow ones — to show pollution. The Montana Department of Environmental Quality no longer approves new wells that are not at least 25 feet deep.

“The majority of public water supply wells generally take water from deep aquifers that are not subject to the same problems,” said Shelley Nolan of the department’s Public Water Supply Program.

She added that public water supplies are routinely tested.

The state environmental agency advises landowners concerned about their private wells to test their water annually for coliform bacteria and nitrates.

Additional testing can be done for contaminants that may be specific to the area.

Well owners also should test their water if there is a change in the water’s taste, odor, or appearance; after the well system is serviced; or after flooding.