Digital data set describing principal aquifers in the conterminous US

This digital data set describes productive aquifers in the conterminous United States. The data set was generated from a U.S. Geological Survey 1:7,500,000-scale map of productive aquifers of the conterminous United States.本数字数据集描述了美国本土的富水含水层。该数据集源自美国地质调查局（U.S. Geological Survey）编制的1:7,500,000比例尺美国本土富水含水层地图。