The indicator measures only the potential for pesticides to run off farm fields. It does not estimate actual pesticide loss. Research has shown that pesticide loss from farm fields can be substantially reduced by management practices that enhance the water holding capacity and organic content of the soil and reduce water runoff. Where these practices are being used, the potential loss measured by this indicator will be over-estimated. Pesticide loss from farm fields does not always translate to water quality impairment.
Pesticides degrade during transport from the farm field to the water body.
Dilution by runoff from non-cropland areas in the watershed will also reduce concentrations observed in surface water. The indicator does not include fruits, nuts, and vegetables. Watersheds with large acreage of these crops will have a greater risk of water quality contamination than shown by this indicator. Estimates using the NRI report conditions on non-federal rural lands. In watersheds with significant Federal or Tribal lands not inventoried in the NRI, estimates may not reflect the vulnerability accurately.