Section 303(d) of the Federal Clean Water Act requires states to identify waterbodies that are not meeting water quality standards and to develop total maximum daily pollutant loads for those waterbodies. A total maximum daily load (TMDL) is the amount of a pollutant that a waterbody can assimilate without exceeding the established water quality standard for that pollutant. Through a TMDL, pollutant loads can be allocated to point sources and nonpoint sources discharging to the waterbody. The study area for this project consists of the Boeuf River and Bayou Macon basins in southeastern Arkansas. For both basins, the headwaters begin southeast of Pine Bluff and the general drainage pattern is southward into Louisiana. The study area comprises the Arkansas Department of Environmental Quality (ADEQ) Planning Segment 2A and is located entirely within the Delta ecoregion. The study area is about 86% cropland (mostly soybeans, cotton, and rice). The majority of the soybeans and cotton are irrigated, and essentially all of the rice is irrigated. The primary source of irrigation water is the alluvial aquifer, which has high concentrations of dissolved minerals in some areas. A total of six reaches in the Bayou Macon and Boeuf River basins are included on the Arkansas 303(d) list as not supporting the aquatic life use due to exceedances of water quality standards for either siltation/turbidity, chloride, sulfate, or total dissolved solids (TDS) as shown in Table ES.1. The applicable numeric water quality standards for these reaches are 75 NTU for turbidity (because ADEQ considers all six reaches to be channel-altered), 90 mg/L chloride for Boeuf River, 48 mg/L chloride for Big Bayou and Oak Bayou, 411 mg/L TDS for Oak Bayou, 460 mg/L TDS for Boeuf River, and 30 mg/L sulfate for Boeuf River.