POLSON - Nitrate pollution in groundwater remains low in Flathead Lake and upstream drainages, despite burgeoning development in Flathead County during the last 10 years.
But nitrate levels have soared to almost four times the recommended health standard in one area of the Flathead Basin, a Bureau of Mines and Geology hydrologist told the Flathead Basin Commission on Wednesday.
The public health standard for nitrate concentrations in groundwater calls for less than 10 milligrams of the pollutant per liter of water. Some wells in the Lost Creek/Tally Lake area show nitrate concentrations as high as 38 milligrams per liter, according to the bureau's most recent monitoring, which occurred in 2003, he said.
The reason for the increase in pollution upstream from Kalispell is unclear. Residential development, agricultural practices and commercial uses all have changed or increased over the last few years, and all could play a part, LaFave said.
"It would be a good master's thesis for some graduate student from the University of Montana to come up here and figure out what is going on," he said. However, funding for such a study - estimated at about $60,000 - has not been available.
Nitrates in groundwater are a concern statewide because of the potential health effects on human fetuses and infants.
"There are very few places in the state where concentrations are this high," LaFave said of the Lost Creek Alluvial Fan area, as it is called. It was created by a major outwash of water in glacial times.
LaFave and others from the Bureau of Mines also sampled wells in the Evergreen area near Kalispell, one of the fastest growing areas in the Flathead region. The study also included wells in the "pothole lake" area north of Bigfork, the lowlands or "delta" at the north end of Flathead Lake and wells along the Flathead Lake shoreline where, unlike the other areas, most wells tap water stored deep in bedrock fractures.
Katie McDonald, LaFave's colleague at the Bureau of Mines, said data from wells the agency collected in the Evergreen area are difficult to interpret.
Since much of the area now is sewered, one would expect that pollution associated with sewage would have decreased during the last few years.
Instead, the pollution levels seem to be about the same as they were prior to sewage treatment.
On the other hand, development in the area has continued at a fast clip. McDonald quoted a Montana Department of Agriculture estimate that 22 percent of Flathead farmland was lost to subdivisions between 1992 and 1997. Growth seems to have continued at a similar rate since then.
So perhaps the decrease in pollution brought on by sewage treatment was offset by the increase in pollution brought by the dynamic growth that continued after the sewer system was built.
The contribution of shoreline development and near-shoreline development to pollution of Flathead Lake is difficult to measure, because of the difficulty in measuring how much water enters the lake from the fractured bedrock aquifers that serve as the source of well water, the scientists said.
"We need groundwater flow information to evaluate the effect" of groundwater on lake water quality, said James Craft of the University of Montana Flathead Lake Biological Station at Yellow Bay. The research station has been participating in the groundwater studies of the basin, and the Confederated Salish and Kootenai Tribes have also shared information the tribes' water-quality experts have developed.
There is no question that human development on the lake shore has affected groundwater quality, the scientists said. Complaints about algae blooms in shallow bays continue to come in to the Biological Station.
Some wells, even some very deep wells, at Finley Point, along Polson Bay and elsewhere are definitely showing signs of nitrate pollution. The question is not if the lake is being affected by shoreline development but by how much, the scientists said.
Because of the complex geologic structure around the lake, "the lake perimeter will be toughest to get reliable data on (pollution) loading into the lake," LaFave told the Flathead Basin Commission.
A final report on the Bureau of Mines' Flathead Basin groundwater assessment is being prepared and will be available at the bureau's groundwater assessment Web site, www.mbmg.mtech.edu. The Web site also has detailed information, including maps, charts, tables and analysis on groundwater studies throughout Montana. The Flathead Basin has probably been the subject of the most detailed study so far, LaFave said.
The 22-member Flathead Basin Commission is a nonregulatory citizens group created by the state Legislature to monitor and protect water quality in Flathead Lake and associated upstream drainages.
In other business, the commission discussed a plan to hire an executive director to better deal with finance, grant-writing and technical issues that have presented themselves as the agency has matured and its goals shifted from study to action.
The staff member now responsible for the commission's day-to-day business is public information officer Mark Holston of Kalispell. Holston's job would be reduced to half-time or perhaps eliminated, with public-information functions contracted out.
Dave DeGrandpre, the commission's current chairman, said a job description for an executive director would include such skills as hydrology, budgeting, financial accountability and grant writing. Holston, of course, could apply for the executive director job if he chose to.
Reporter John Stromnes can be reached at 1-800-366-7186 or at jstromnes@missoulian.com
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