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. This report presents a TMDL for dissolved oxygen (DO) for Big Creek near Sheridan in central Arkansas (reach 08040203-904). Both the final 2002 Arkansas 303(d) list and the draft 2004 Arkansas 303(d) list cited Big Creek as not supporting its designated use of aquatic life due to low DO values measured in the stream. Big Creek is a relatively small stream (drainage area at the mouth is 21.7 square miles) that normally experiences periods of zero flow in the summer. The land use in the watershed is approximately 58% forest, 31% pasture, 10% urban, and 1% water. The only facility with a permitted point source discharge into Big Creek is the City of Sheridan wastewater treatment plant (WWTP). The treatment system at this facility consists of three large ponds in series. The WWTP currently discharges treated wastewater to Big Creek under a hydrograph controlled release (HCR) scenario. With the HCR, the allowable effluent flow rate can be as much as 32% of the stream flow in Big Creek upstream of the outfall. However, this also means that the facility cannot discharge when Big Creek is not flowing. The most recent renewal of the City of Sheridans discharge permit will impose more stringent limits for carbonaceous biochemical oxygen demand (CBOD5) and ammonia nitrogen (NH3-N) starting March 1, 2008. The Arkansas Department of Environmental Quality (ADEQ) made the final permit limits more restrictive because ADEQs routine monitoring data in Big Creek downstream of the WWTP showed enough low DO values to cause Big Creek to be classified as impaired due to organic enrichment/low DO on the 303(d) list. However, analysis of the ADEQ monitoring data and the WWTP effluent data indicates that the WWTP is not the primary cause of low DO values measured by ADEQ in Big Creek.