A preliminary appraisal of the effects of agriculture on stream quality in southwest Georgia

Abstract

Water—quality and suspended—sediment samples were collected in two basins in southwest Georgia to determine whether water—quality problems have resulted from agricultural practices. Samples were collected monthly and during periods of storm runoff from December 1976 through July 1978. Concentrations of chemical constituents relevant to agricultural practices were found to be low, even during periods of storm runoff. Concentrations of total nitrogen and total phosphorus ranged from 0.30 to 1.60 and 0.01 to 0.42 milligrams per liter, respectively. Copper, arsenic, lead, mercury, and zinc concentrations were low and did not exceed Georgia Department of Natural Resources (1977) or U.S. Environmental Protection Agency (1977) standards for safe drinking water. Concentrations of suspended sediment and total nitrogen were found to remain relatively constant over a wide range of water discharge. Concentrations of total phosphorus showed a better relation to water discharge at Little River near Lenox than at Spring Creek near Iron City. Dissolved—solids concentrations in both streams generally decreased with an increase in water discharge. Average annual yields of selected constituents were low. Total nitrogen and total phosphorus yields were 0.60 to 0.63 and 0.04 to 0.06 tons per year per square mile in Little River and Spring Creek basins. Atrazine, butylate, and ethroprop pesticides were detected in concentrations up to 0.91 micrograms per liter in storm— runoff samples collected during the active farming season.