Effects of Agricultural Intensity on Nutrient and Sediment Contributions within the Cache River Watershed, Arkansas

Abstract

Streams in agricultural lands tend to serve as a conduit for nutrient pollution. These streams are often modified and have reduced riparian zones, resulting in agriculture being the leading cause of nonpoint source pollution into streams of the United States. Eutrophication within the Gulf of Mexico has been attributed to nutrient and sediment contributions from watersheds within the greater Mississippi River Basin. One such watershed, the Cache River Watershed (CRW) located in northeast Arkansas, was assessed to determine the impacts of agricultural intensity on water quality at a local scale. The objective of this study was to determine the influence of agricultural activity on nutrient and sediment contributions to the CRW. Following American Public Health Association guidelines, physicochemical parameters, turbidity, and total nutrients (nitrogen and phosphorus) were analyzed weekly from October 2017–September 2020 at 12 subwatersheds of four varying agricultural intensities (low, low moderate, moderate high, high). Results indicate that physicochemical parameters increase (pH, conductivity, temperature) or decrease (dissolved oxygen) with increased agricultural intensity. Similarly, turbidity and total nutrients also increase (significantly for turbidity and total phosphorus) with increased intensity. Contributions of sediment and nutrients in the CRW not only influence local stream health but also contribute to hypoxia in the Gulf of Mexico.

Keywords

• agricultural intensity
• total nutrients
• turbidity
• nonpoint source pollution
• Cache River Watershed