165-Integrated BMP Assessment for Improving Water Quality in a Rice-Soybean Dominated Watershed in the Arkansas Delta.

Abstract

This study focused on evaluating performance of Best Management Practices (BMP) in controlling sediment and nutrient losses from an agricultural watershed to meet Total Maximum Daily Load (TMDL) requirements. The study was conducted in the L'Anguille River watershed, an intensively managed agricultural area consisting of more than 2,250 km`, 80% of which are in row crop agriculture; predominantly soybeans, rice, and cotton. The drainage from these fields flows into the river carrying potentially large amounts of sediment, nutrients, and pesticide residues. The entire length of the L'Anguille River has been designated impaired due to high sediment concentrations assumed to be coming from intensive row crop agriculture. A total of 52 different BMP scenarios were analyzed and their impacts on water quality improvements were evaluated for three implementation schemes: optimization, targeting in high priority subbasins, and random placement. The results indicated that BMP optimization always resulted in the greatest reduction of sediment, total P, and total N losses from the watershed under a given cost-constraint compared to the targeting and random placement schemes. The results of this study indicated that under limited resources scenarios available for BMP implementation and maintenance, watershed management should focus on optimizing BMP placement so that maximum pollutant reduction from the watershed can be accomplished.