Abstract: This report lists the machine-readable data files developed for the Madison Limestone and Northern Great Plains Regional Aquifer System Analysis (RASA) projects that are stored on magnetic tape and available from the U.S. Geological Survey. Record format, file content, and size are given for: (1) Drill-stem-test data for Paleozoic and Mesozoic formations; (2) geologic data from the Madison Limestone project; (3) data sets used in the regional simulation model; (4) hydraulic-head data for the Lower and Upper Cretaceous aquifers; and (5) geologic data for Mesozoic formations of the Northern Great Plains.

From abstract: During fiscal years 1978 through 1981, the U.S. Geological Survey contracted for the acquisition and analysis of hydrologic data from 104 surface water stations, 26 ground water stations, and 15 precipitation gages as well as for several hundred miscellaneous surface water measurements of flow and water quality. The work was performed in Montana, North Dakota, Wyoming, Utah, New Mexico, and Oklahoma, terminating at the end of the fiscal year 1981. This report is an assessment of this contracting effort from the standpoint of cost and of quality control measures employed to ensure an acceptable product.

From objectives and scope: The objectives of the study were to: (1) Determine the geographic extent of the minable lignite beds and identify aquifers down to a depth of about 400 feet beneath the lower minable lignite; (2) assess the ground-water flow regime in all aquifers found; (3) evaluate the flow characteristics of the two streams draining the study area; and (5) qualitatively assess the impacts mining might have on the hydrologic system.

Purpose and scope: The purpose of this investigation is to describe changes in the ground-water levels and levels of surface-water bodies and to ascertain whether those changes can be ascribed to the raising of the level of Lake Audubon, or to the subsequent filling of the McClusky Canal, or both. The changes will be determined by analysis of water-level records obtained from observation wells.

From introduction: The specific objectives of the study were to: (1) Determine the premining hydrologic and geochemical conditions in the 28 mi2 area; (2) provide a premining data base from which to measure the magnitude of change in the hydrologic system due to coal mining; and (3) determine the probable effects of mining on the water resources in the area.

Abstract: A digital simulation model was used to analyze regional ground-water flow in the Madison Group aquifer in the Powder River Basin and adjacent areas. Most recharge to the aquifer originates in or near the outcrop areas of the Madison in the Bighorn Mountains and Black Hills , and most discharge occurs through springs and wells. Results from the model calculations indicate that the total flow through the aquifer in the modeled areas was approximately 200 cubic feet per second (5.7 cubic metres per second). The aquifer can probably sustain increased ground-water withdrawals probably would significantly lower the potentiometric surface in the Madison aquifer in a large part of the basin. The digital model could better predict the effects of withdrawals if more accurate estimates of the storage coefficient, transmissivity, and leakance could be obtained.

From objectives and scope: This study was undertaken in response to U.S. Bureau of Land Management concerns for the water resources of the Wibaux-Beach area in the event of lignite mining. The objectives of the study were to: (1) Define the stratigraphic sequence within a few hundred feet above and below the minable lignite; (2) define the premining hydrologic and geochemical regime of the Wibaux-Beach deposit area; and (3) describe some of the hydrologic implications of the strip-mining process. A fourth objective, the establishment of historical data base with which to access any modifications to the system attributable to future mining, was accomplished as a byproduct of the other three.