Idaho ag officials: Don't blame cows for nitrate

TWIN FALLS (AP) - A recently released report from the Idaho Department of Environmental Quality shows that 16 percent of water samples taken from 4,200 wells across the state have too much nitrate. But agriculture officials say cow manure, often blamed for high nitrate levels, isn't the problem.

Irene Nautch, the DEQ's drinking water protection coordinator in Twin Falls, said agriculture is one source of nitrates in groundwater, along with seepage from private septic systems and lawn and garden fertilizers.

"We don't get very far by pointing fingers," Nautch told The Times-News.

Idaho Department of Agriculture Dairy Bureau Chief Marv Patten contends manure simply isn't the cause of the high nitrate levels. Patten said the amount of nitrogen in manure is insufficient for growing many crops, forcing growers to apply additional nitrogen in the form of fertilizer to compensate.

"Manure is not an issue," Patten said.

The DEQ water quality report found that 691 water samples taken from 4,244 wells statewide exceed the 10 parts-per-million threshold set by federal health standards. Natural levels of nitrate in groundwater rarely exceed 1 ppm, and researchers say any level over 2 ppm indicate that human activities have put nitrate in groundwater.

In Twin Falls County, 6 percent - 35 out of 618 - of wells tested exceed the 10 ppm threshold. That's the same percentage reported in the urban Pocatello area.

In the Marsh Creek area of Cassia County - the area of highest concern in the state - 23 percent of the wells tested exceed the federal health standard.

Many producers who spread manure on their fields are required to file nutrient management plans with the state agriculture department to ensure proper application of nitrogen, Patten noted. In addition, the high cost of fertilizer discourages over-application of nitrogen, Patten said.

Biological processes and climatic conditions along with the physical and chemical properties of a soil influence the route that ends with harmful nitrates in groundwater.

"We all have to do our part in finding a solution," Nautch said.