Watershed Comparison of the Effects of Land Use on Water Quality

Abstract

A comparison of water quality was conducted during October 2019 on an agricultural watershed and a forested watershed, both located in northern middle Tennessee and a small portion of one in southern Kentucky. The Little Trace Creek watershed (HUC-12-051100020101) is approximately 25,426 acres and 61% agriculture, mostly cattle and poultry operations. The Jennings Creek watershed (HUC-12-051301060302) is approximately 36,075 acres and 84% forested. The land use data was collected from the Multi-Resolution Land Characteristics Consortium Website. Conductivity and dissolved oxygen were measured using a YSI® Professional Plus Multiparameter Meter on three separate occasions on three separate streams within each watershed. The data indicates a noticeable difference in water quality between these two watersheds. The dissolved oxygen measurements showed more variation in the agricultural watershed (SD of 2.2) than in the forested watershed (SD of 0.5). The forested watershed showed a higher average dissolved oxygen level at 7.61 mg/l than the agricultural watershed at 7.23 mg/l. The conductivity was also more variable for the agricultural watershed (SD of 14.1) than the forested watershed (SD of 7.4). The agricultural watershed had an overall average conductivity of 276.2 µs/cm as opposed to the forested watershed at 253.4 µs/cm. One stream in the agricultural watershed stream had a lower average dissolved oxygen at 5.21mg/l, which is close to the minimum value of 5.0 mg/l necessary for good water quality. Further research could determine the causation of the lower dissolved oxygen.