Selecting critical areas for nonpoint-source pollution control

SEVERAL state and federal programs have investigated offering financial incentives to farmers for implementing best management practices (BMPs) to control nonpoint-source pollution on agricultural land. The financial incentives, technical assistance, and educational programs that comprise these pollution control efforts, however, are costly. The concept of targeting funds for land treatment on critical areas has thus gained importance. Unfortunately, few attempts have been made to establish criteria for selecting critical areas. Even the Rural Clean Water Program (RCWP) and Model Implementation Program (MIP), both of which stipulated that projects should attempt to determine critical water quality areas, provided no guidelines for making such assessments (1, 5). Coupled with what is known about pollutant transport processes, however, guidelines for selecting critical areas can be developed. Critical-area criteria There are two distinct critical-area perspectives: the land resource perspective and the water resource perspective. Critical areas, from the land resource perspective, are those lands on which soil loss exceeds the rate at which soil can be replaced by natural processes-the soil loss tolerance or T value. Although areas of severe soil loss often are the most critical areas for treatment of agricultural nonpoint-source pollution, this need not be the …