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Eutrophic conditions, indicative of excessive algae production, are the predominate cause of impairment in Kansass lakes. When an overabundance of nutrients enters the lake, algal growth increases significantly. Numerous negative effects occur ranging from taste and odor problems in drinking water to objectionable algal growth interfering with recreational activities.

The purpose of the eutrophication Total Maximum Daily Loads (TMDLs) is to reduce the amount of nutrients entering the lake so that the designated uses of the lake are supported. Developed by the Kansas Department of Health and Environment (KDHE) Lake Monitoring Program, endpoints were determined through the use of visual assessment, water quality, and water clarity data. Before nutrient load reductions are calculated, the nutrient that is causing the impairment needs to be determined. The most accurate way to determine the limiting factor for algal growth is to do a bioassay that tests the growth response of the algae to the nutrient (s) and light. Because it is not feasible to bioassay each lake in a large monitoring network, calculating the limiting factor with data over the period of record is the commonly used method.

Light, phosphorus, and nitrogen limitations are determined through graphing the deviations of the trophic state variables. For all eutrophication TMDLs, a total phosphorus reduction is required to meet the chlorophyll a endpoint. If nitrogen were indicated to be more important to algal growth, a nitrogen concentration endpoint would be put in place as well. If a light limitation is indicated the lake is classified as being Argillotrophic, then a siltation TMDL is written. This paper will examine this TMDL procedure used to set Kansas lake TMDLs.