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

Citation:  Pp. 123-129 in Total Maximum Daily Load (TMDL) Environmental Regulations–II Proceedings of the 8-12 November 2003 Conference (Albuquerque, New Mexico USA), Publication Date 8 November 2003.  .(doi:10.13031/2013.15547)
Authors:   B.E. Haggard
Keywords:   Streams, Phosphorus, Nutrient Criteria, Trophic Status, Watershed Management

Nutrient and chlorophyll a concentrations are generally the basis for trophic state classification because of the strong relation between the two, particularly in lakes. However, this relation is often much weaker in streams because the effect of physical factors on the production and composition of algae. The occurrence of eutrophic conditions in stream is most often related to nuisance algal biomass and excessive nutrient concentrations; the impairment of the beneficial uses of streams from these factors is protected by narrative or numeric criteria. Recently, a guidance document has been released on the development of numeric nutrient criteria in streams, and this approach considers the statistical distribution of nutrient concentrations in streams. We use recently published investigations on stream nutrient concentration and limitation in Oklahoma streams to present potential scenarios in the development of total phosphorus (TP) criteria and compare these investigations with recently promulgated TP criterion in Oklahomas Scenic Rivers. The percentile distribution of median TP concentrations in Oklahoma streams varied across the state, particularly between the Ozark Highlands and Ouachita Mountains. The 25th percentile of median TP concentrations in Ozarks streams was generally greater than Oklahomas Scenic River TP criterion, except in smaller headwater streams. It may be possible to relate soluble P concentrations in Ozark streams to a simple measure of trophic state and determine soluble P concentrations which may limit the potential for algal growth in Ozark streams.

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