Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Improving TMDL Determinations Through Assessment of Benthic Macroinvertebrate Communities

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Watershed ManWatershed Management to Meet Water Quality Standards and TMDLS (Total Maximum Daily Load) Proceedings of the 10-14 March 2007, San Antonio, Texas  701P0207.(doi:10.13031/2013.22439)
Authors:   Adrienne D Viosca, Y Jun Xu, William E Kelso
Keywords:   benthic macroinvertebrates, biological monitoring, water quality, TMDL, Ouachita River Basin, Louisiana

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.

(Download PDF)    (Export to EndNotes)