The geochemistry and hydrogeology of abandoned homestead reservoirs in the Shawnee National Forest, southern Illinois

The main purpose of this study was to determine if geology controls the water quality and hydrology of abandoned, hand-dug, homestead reservoirs scattered throughout the Shawnee National Forest. Field, laboratory, and statistical methods were used to identify the hydrologic and geochemical nature of the reservoirs in the SNF. Field methods included conducting rising head tests and collecting water quality samples. Laboratory methods included analyzing water quality samples. Statistical analyses of the data were performed on parameters collected from the field in August, 2005. Rising head tests were collected on ten of the 27 reservoirs investigated. Results indicate that the majority of reservoirs are cisterns and not directly receiving groundwater discharge. Water quality samples were collected in August, 2005 from each of the twenty-seven reservoirs included in this study and analyzed for common cation and anion constituents and field parameters. Statistical analyses were conducted on the 35 variables collected from each reservoir. Correlation coefficients, principal components analysis (PCA), and q-mode hierarchical cluster analysis (HCA) reduce the variables into the major factors controlling water quality. Water quality appears to be controlled mainly by reservoir design. Two main groups emerged; one comprised of reservoirs with large diameter casings and shallow water depth, while the other consisted of reservoirs with small diameter casings and deep water depth.