Procedure for evaluating observation-well networks in Wyoming, and application to northeastern Wyoming, 1986

A sequence of steps was developed for evaluating and modifying the existing, long-term, observation-well network in any part of Wyoming. The State was subdivided geographically into nine groundwater areas, including the northeastern Wyoming groundwater area, based on major structural features. Northeastern Wyoming was the first of the nine areas to be evaluated using these procedures. The stratigraphic units of Wyoming were grouped into five rock units on the basis of age, similar depositional environments, and water-yielding properties. Activities likely to affect groundwater in northeastern Wyoming were evaluated. The most important monitoring needs in the area are related to: (1) Oil-field waterflooding; (2) surface mining of coal; (3) increasing municipal use of groundwater, and (4) need for general resource information. The 18 observation wells in the existing (1986) network meet most of the needs identified. Seven additional wells need to be added to the network, whereas four wells in the network can be discontinued. Water level data from the 18 observation wells are presented by county. Maps and hydrographs are accompanied by brief discussions of information related to the records obtained. (USGS)