Reconnaissance of quality of water from farmstead wells in Tennessee, 1989-90

Data for fecal bacteria, nitrate, organic compounds, iron, manganese, and pH were collected during 1989-90 as part of a statewide reconnaissance of ground-water quality in 150 domestic farm wells in Tennessee. The biological and chemical data for each well were grouped according to eight of the nine principal aquifers in the State and analyzed for local and regional variation within and among these aquifers. Water samples from 45 percent of the wells statewide tested positive for fecal cot[form or streptococci bacteria. Regionally, samples from 20 percent of the wells in the primarily unconsoli- dated sedimentary aquifers in western Tennessee tested positive for either or both bacteria, compared with samples from 54 percent of the wells in the consolidated bedrock aquifers in the central and eastern parts of the State. Although nitrate nitrogen equaled or exceeded the 10.0 milligrams per liter primary drinking-water standard in only 3 percent of the wells sampled statewide, samples from 20 percent of the wells had nitrate nitrogen concentrations that exceeded 3.00 milligrams per liter possibly indicating human influence on ground-water quality. Estimated total concentrations of organic compounds were less than 5 micrograms per liter in samples from 92 percent of the wells statewide. Concentrations of iron and manganese equaled or exceeded their secondary standards of 300 and 50 micrograms per liter in samples from 35 and 25 percent of the wells, respectively, with the largest concentrations identified in samples from the alluvial and Pennsylvanian sandstone aquifers. Samples from 25 percent of the wells, had a pH below the lower secondary standard of 6.5 units, with most of these samples from the unconsolidated sedimentary aquifers in western Tennessee.