TWIN FALLS, Idaho (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 with the DEQ told The Times-News that agriculture is one source of nitrates in groundwater, along with seepage from private septic systems and lawn and garden fertilizers.

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.