Beaver Lake Water Quality Enhancement Project Data Analysis

This study consists of analyses of the water quality data generated during the 4 years of sampling for the Beaver Lake Water Quality Enhancement Project along with limited data on best management practices (BMPs) implemented by farmers in the studied subwatersheds. The water quality data were collected from 12 stream sites, 3 overland flow sites, and 5 lake sites. The water quality data were collected by Environmental and GIS Consulting, Inc. (EGIS) and compiled in a report to the U.S. Army Corps of Engineers, Little Rock District (Corps) and the Arkansas Soil and Water Conservation Commission (ASWCC) in June 1996.The study described in the attached report analyzed the stream and lake data for trends and parameter relationships, examined the effects of statistically regenerated data in the original study, assessed the eutrophic state of Beaver Lake, and evaluated the impacts of BMP implementation on water quality. Trend analysis on the data indicated decreasing trends for orthophosphate and total phosphate at all stream and lake sites, although most of these trends were not statistically significant and there was uncertainty in the quality of the phosphorus data. Trends in the other water quality parameters were non-uniform (not all positive or all negative) and showed few significant trends for individual sites. Calculation of the correlation between BMP implementation and parameter trends suggested that a relationship may exist between greater extent of BMP implementation and decreases in total P; however, this relationship is not seen with ortho P. The BMPs may contribute to the apparent downward trend in phosphorus values during the study period, however, a cause and effect relationship cannot be established. Other parameters are not significantly correlated to the relative extent of BMP implementation. The trophic status of Beaver Lake is predominantly eutrophic based on primary productivity measured as chlorophyll a in this study and total P levels obtained from a USDA. ARS study by Haggard. Correlation coefficients for the relationships between different parameters were calculated. Although some relationships were statistically significant, there was only a weak association between the parameters in that the correlations were far from :t 1, meaning that one parameter could only explain a small amount of variation in the other parameter. The effect of regenerated flow data in the original study was examined and it was determined that the flow data regeneration is unlikely to be a major source of inaccuracy.