Hydrogeologic data for the Dakota aquifer system in Nebraska

Data utilized in preparing an interpretive hydrogeologic report on the Dakota aquifer system in Nebraska are summarized. The study area is a 370,000 sq mi area that includes all of Kansas and Nebraska and parts of Arkansas, Colorado, Missouri, New Mexico, Oklahoma, and Texas. The broad objective for each Regional Aquifer-System analysis (RASA) study is to assemble geologic, hydrologic, and geochemical information; to analyze and develop an understanding of the hydrogeologic system; and to develop predictive capabilities that will contribute to effective management of groundwater resources. The Central Midwest RASA project includes the study of the major regional aquifers that occur in the stratigraphic interval between the Precambrian surface and the top of the Great Plains aquifer system. The Dakota aquifer system in Nebraska, which is the equivalent of the Great Plains aquifer system, can best be defined as those sandstones and shales occurring in the stratigraphic interval between the base of the Cretaceous system and the top of the first major sandstone bed below the Cretaceous Greenhorn Limestone. This aquifer systems underlies approximately 94 percent of the State. Distribution of data sites is not uniform across the State. Although the aquifer systems underlies all or parts of 88 of Nebraska 's 93 counties, hydrogeologic data on the Dakota are available only for 83 counties. Individual data sites were selected on the basis of the completeness and representativeness of data for the site and to provide an adequate areal distribution of data needed to describe the hydrogeology of the aquifer system. Four tables are used to summarize hydrogeologic data. (USGS)