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Louisiana uses chemical and physical water quality parameters exclusively to determine sediment and nutrient total maximum daily loads (TMDLs) for its surface waters. However, current TMDL criteria are based on broad national standards and may not be applicable to the unique subtropical stream systems in the Gulf coastal plain. A watershed-wide monitoring of the benthic macroinvertebrate community is being conducted on Flat Creek in central Louisiana, which has been classified as impaired due to oxygen demand. Objectives of this study are to characterize the current condition of the benthic community in an area where insufficient information exists; determine if a relationship exists between macroinvertebrate community structure and stream physicochemistry, particularly dissolved oxygen; and assess the benefits of incorporating biological assessments into the development and implementation process for Louisiana TMDLs. Monitoring locations were selected throughout the Flat Creek watershed, and macroinvertebrate samples and water quality data were collected in a 160 m stream reach at each location during the spring of 2006. In addition, monthly water samples were analyzed for dissolved oxygen and velocity measurements were taken. The macroinvertebrate samples are being identified to the family level in order to quantify species abundance, taxa richness, and pollution-sensitive taxa. Spatial patterns of the biological indices across the watershed will be analyzed for relationships with the monthly water quality measurements. This paper presents preliminary results of the study and discusses the status of the current TMDL process in Louisiana.