Susceptibility of major aquifers to surface contamination -- Holmes, Humphreys, Issaquena, Sharkey, Washington, and Yazoo Counties, Mississippi

A geographic information system was used to integrate digital spatial data sets describing geology, slope of the land surface, depth to water table, soil permeability, and land use/land cover to rate the relative susceptibility of unconfined parts of the Mississippi River alluvial, Cockfield, and Sparta aquifers in west-central Mississippi to contamination from surface sources. Areas were rated as having a very low, low, moderate, high, or very high susceptibility to contamination from surface sources. Less than 1 percent of the Mississippi River alluvial aquifer has a very high susceptibility to surface contamination, 35 percent has a high susceptibility, 62 percent has a moderate susceptibility, and 2 percent has a low susceptibility. About 43 percent of the Cockfield aquifer has a high susceptibility to surface contamination, 57 percent has a moderate susceptibility, and less than 1 percent has a low susceptibility. About 41 percent of the Sparta aquifer has a high susceptibility, and less than 1 percent has a low susceptibility, and 1 percent has a low susceptibility. For all three aquifers, less than 1 percent has a very low susceptibility to surface contamination.