1. Hydrology of the Arapahoe aquifer in the Englewood-Castle Rock area south of Denver, Denver Basin, Colorado [cartographic material] Yale Public content 1978. 2014-01-21T15:56:07Z. 2014-02-04T23:15:20Z. Hillier, Donald E. The Survey. English. Public. Colorado, Douglas County, Arapahoe County, and Elbert County.