Managing Infiltration to Avoid Water Quality Problems

Recent newspaper headlines in the Des Moines Register (e.g., October 19, 1994: Water is laced with pesticides report finds- 14 million affected and July 14, 1995: River boosted drinking water nitrate levels - farm fertilizer suspected ) illustrate some of the water quality concerns that exist for the off-site movement of pesticides and nutrients from treated fields to water resources. The major water quality concerns from pesticides relate to the possible impact on human health when found in surface and groundwater, and on the health of the aquatic ecosystem when found in surface waters. The major water quality concerns from nutrients, namely nitrate-nitrogen (NOrN), ammonium-nitrogen (NH4-N), and orthophosphate-phosphorus (P04-P), relate to the 10 mg/L (or ppm) drinking water standard for NOrN for prevention of blue baby or methemoglobinemia in infants, the level of concern of about 2 mg/L for NH4-N to prevent fish toxicity from free ammonia (NH3), and the levels of concerns in rivers of 0.050 mg/L and lakes of 0.025 mg/L for P04-P to prevent the acceleration of eutrophication