Hydrogeological restrictions to saline ground-water discharge in the Red River of the North drainage basin, North Dakota

Discharge of saline water from bedrock aquifers along the eastern margin of the Williston basin is restricted by surficial glacial till and lacustrine deposits in the Red River of the North drainage basin. Water from these aquifers reaches the surface by (1) diffusion; (2) slow, upward seepage along zones of relatively larger hydraulic conductivity in the till and lacustrine deposits; or (3) flow from artesian wells. Ground-water quality varies near the surface because of mixing of water being discharged from bedrock aquifers with shallower ground water in the surficial deposits. Ground-water quality, hydraulic-gradient, and hydraulic-conductivity data obtained from pumped-well and slug tests indicate that flow in the surficial deposits is eastward, but at slow rates because of small hydraulic conductivities. Base-flow and specific-conductance measurements of water in tributaries to the Red River of the North indicate that focused points of ground-water discharge result in substantial increases in salinity in surface water in the northern part of the basin in North Dakota. Core analyses and drillers' logs were used to generalize hydrogeologic characteristics of the deposits in the basin, and a two-dimensional ground-water-flow model was used to simulate the basin's geohydrologic processes. Model results indicate that the ground-water flow paths in more » the bedrock aquifers and surficial deposits converge, and that water from the bedrock aquifers contributes to the overall increase in ground-water discharge toward the east. Model results are supported by water-quality data collected along an east-west hydrogeologic section. « less