Submitted to: Aquatic Bioassessment and Biocriteria Symposium
Publication Type: Proceedings
Publication Acceptance Date: February 28, 2003
Publication Date: April 15, 2003
Citation: KUHNLE, R.A., SIMON, A., KNIGHT, S.S. DEVELOPING LINKAGES BETWEEN CLEAN SEDIMENT INDICES AND BIOLOGICAL IMPAIRMENT. Proceedings of Central Plains Aquatic Bioassessment and Biocriteria Symposium. 2002. CD-ROM. Interpretive Summary: Changes in the movement or storage of clean sediment (sediment carrying no attached contaminants) in the rivers and streams of the United States has been identified as a major problem affecting the quality of the water of streams and rivers in the United States. The states, territories, and tribes of the country have been charged to develop plans to evaluate the causes of excess sediment affecting the nation's rivers and streams and to suggest remedies. These plans are termed TMDL's and have been mandated by the Clean Water Act section 303. The Total Maximum Daily Load (TMDL) for clean sediment of a stream or river may be defined as the amount of sediment that the water body can handle without negative impacts to its designated uses. Designated use may be defined as the use that has been specified for a given river or stream. These uses may include recreation, drinking water supply, navigation, and supporting an unimpaired biological community. In this study the relation between different levels of sediment carried by several streams in the state of Mississippi have been related to indices relating to the organisms living on the bottom (benthics) of the streams. It was found that the total number of benthic organisms and the number of taxa (or groups of organisms) was related to the length of time a given level of sediment was maintained in the streams. This result is the first step towards defining the maximum levels of sediment that organisms in streams can tolerate without harm. This information is needed by the states for the development of TMDLs for clean sediment.
Technical Abstract: Clean sediment has been identified as the largest named pollutant in the 303(d) listed sites in the United States. The methods used by states to list streams as impaired by sediment is variable. Standard scientifically-based assessment tools are needed to determine the likelihood streams are impaired by clean sediments. In this study, linkages were sought between sediment indices and biologic indices for streams with detailed records of flow discharge, suspended sediment transport , and biological data to use as analogues in the evaluation of sites lacking detailed data. Preliminary analyses show that as durations of suspended sediment concentration at or above 1000 mg/l increase, the total number of organisms and the number of taxa tend to decrease for benthic organisms. The data for this determination was from streams in the Mississippi Valley Loess Plains in the state of Mississippi.