6.1 DENVER BASIN
The Denver Basin is a structural basin that encompasses the Denver metropolitan area in the Great Plains physiographic province. The center of the basin lies just west of Parker, where the lowermost of four aquifers, the Laramie-Fox Hills aquifer, is approximately 3,000 feet deep. The administrative ground water portion of the basin underlies a 6,700 square mile area extending into Weld County on the north, El Paso County on the south, Jefferson County on the west, and the eastern portions of Adams, Arapahoe, and Elbert Counties on the east (Figure 6.1-1). The basin straddles the boundary between Water Divisions 1 and 2.
The Denver Basin is an important nonrenewable source of ground water for municipal, industrial, agricultural and domestic uses. The eight-county Denver metropolitan area contains 56% of Colorado’s population, or slightly over 2.4 million people according to the 2000 census. The lack of available surface-water rights and accelerated urban growth has resulted in extensive development of the Denver Basin aquifers as both primary and supplemental sources of water supply. As of February 2001, approximately 33,700 wells of record have been completed in the sedimentary rock aquifers of the Denver Basin.
Over the majority of their respective areas, the Denver Basin aquifers are under confined conditions. Given the water-level declines over the past 20+ years, the margins of the confined portions of the aquifers are receding (Figure 6.1-2). Drilling within the basin indicates that the aquifers are very heterogeneous and the porous intervals vary significantly with distance from the source area of the sediments comprising the aquifer. The quantity of recoverable water stored within the Denver Basin is estimated at 200 million acre-feet.