DEVELOPMENT OF THE NATIONAL P INDEX – THE POTENTIAL ROLE OF WTR

The primary water quality concern surrounding phosphorus (P), especially in freshwater bodies, is accelerated eutrophication. The natural aging process of a body of a water body, eutrophication can be accelerated by increased nutrient and sediment loadings. Accelerated eutrophication results in excessive algal growth on the water body surface that inhibits light penetration and depletes available oxygen as the aquatic plant material decomposes. This limits water use for fisheries, recreation, and industry and can contribute to fish kills.As a result of increasing water quality concerns associated with nonpoint contributions of P, increased attention by federal and state agencies has been focused on minimizing P contributions from these sources. In 1999 the U.S. Department of Agriculture and U.S. Environmental Protection Agency, jointly issued the Unified National Strategy for Animal Feeding Operations that outlined three P-based nutrient management strategies one of which was the P Index.A tool to identify areas of P movement from agricultural fields by ranking site vulnerability to P loss was developed. This tool is known as the P Index accounts for both source and transport processes associated with P loss and allows for targeted management.In a P Index evaluation, areas requiring additional management to minimize vulnerability to P loss are identified and appropriate management practices are recommended. Often these practices involve soil conservation, but management practices that have the potential to control dissolved P loss, such as the use of water treatment residuals (WTRs), have the potential to make a contribution to the P Index process.Finally, there is great potential to establish mutually beneficial relationships between the agricultural community with the ability to utilize WTRs for P control and the industries exploring beneficial uses for P binding by-products.