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Technical Report

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water quality monitoring, Illinois River watershed, nutrient management


In Northwest Arkansas, nutrients transported by surface water are a major concern. These nutrients are implicated in causing water quality impairment of lakes in Northwest Arkansas and eastern Oklahoma. The nutrients of concern are nitrogen and phosphorus. Nitrogen and phosphorus stimulate algae production in water bodies and can cause objectionable water quality. Problems associated with algae growth are aesthetic impairment, objectionable taste and odor of potable water, interference with recreation activities, and fish kills in some hyper-eutrophic cases. The sources of these nutrients are primarily from land application of confined animal wastes as soil amendments to pastures. In 1990, the University of Arkansas, Fayetteville Cooperative Extension Service (CES) and U. S. Department of Agriculture Natural Resources Conservation Service (NRCS) initiated a program in the Muddy Fork watershed of the Illinois River. This program focused on implementing best management practices (BMP) in the watershed that would reduce nutrient losses from pastures. Education, technical assistance, and cost sharing was the approach used by these agencies to encourage BMP implementation. The predominant BMPs implemented were nutrient management, pasture and hay-land management, waste utilization, dead poultry compo sting, and waste storage structures. In 1991, the Arkansas Soil and Water Conservation Commission (ASWCC) and the U. S. Environmental Protection Agency (EPA) sponsored a monitoring project in the Lincoln Lake Basin. The Lincoln Lake Basin, part of the Muddy Fork watershed, received appreciable BMP implementation by the CES and NRCS. The objective of this monitoring project was to demonstrate the effectiveness of the implemented BMPs in reducing nutrient transport from the pastures in this intensively managed area. Nutrient transport by Moores Creek and Beatty Branch, the two streams that feed Lincoln Lake, was monitored from September 1991 until April 1994 (Edwards et al., 1996 and 1997). During storm flow conditions, significant decreases in mean concentrations and mass transport of nitrate-nitrogen (NO3-N), ammonia-nitrogen (NH3- N), total Kjeldahl nitrogen (TKN), and chemical oxygen demand (COD) were observed in this watershed and attributed to BMP implementation. There were no decreases in total phosphorus (TP) or total suspended solids (TSS). Likewise, during base flow conditions, significant decreases of NH3-N, TKN, and COD were observed. After the end of this initial monitoring project, the stream monitoring continued on a limited basis in the Lincoln Lake basin. This report will compare the results of continued monitoring to the findings of the first project. This supplemental monitoring was conducted from 1 January 1995 until 30 September 1997.

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