Selected drill-stem-test data from the Northern Great Plains area of Montana

Selected drill-stem-test data were collected for use in the hydrologic analysis of aquifers in the northern Great Plains area of Montana. To supplement existing data defining the potentiometric surface of various aquifers, shut-in pressures recorded during drill-stem tests of oil and gas test wells were used to calculate the altitude of the potentiometric surface. The transmissivity of the aquifers also was calculated if sufficient data existed. Records for 627 drill-stem tests from 523 wells are tabulated in this report. Data include well location, well name, formation tested, well epth, tested interval, date tested, test number, flow period, transmissivity, shut-in pressure, and altitude of water surface. Locations of the wells are shown on a map at a scale of 1:1,000,000. (USGS)