Finding Water The Denver Basin is a structural sedimentary basin that underlies the Denver metropolitan area from the foothills to the eastern plains. This layered, multi-aquifer system is recognized nationally as a major aquifer. Geologic units underlying the Denver Basin aquifer are also rich in mineral fuels with active production of oil and gas. Historically, coal has been produced from the Laramie Formation of the aquifer system. The structural depression referred to as the Denver Basin extends north and eastward outside of Colorado’s boundaries. This larger basin accumulated sediments as the Western Interior Seaway retreated and the Rocky Mountains rose. However, when the state was called upon to determine how the basin’s water should be used, it mapped out a smaller administrative area where it would focus its efforts. This administrative area covers 6,700 square miles 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. The thickest portion of the basin lies just west of the town of Parker, where the LaramieFox Hills aquifer is approximately 3,000 feet below the surface. The Denver Basin bedrock aquifer system consists of water-yielding strata, predominantly sandstones and siltstones, of Tertiary- and Cretaceous-age sedimentary rocks deposited 65-70 million years ago. The northern part of the Denver Basin aquifer system underlies the alluvial aquifer of the South Platte River, and is hydraulically connected to that unconsolidated aquifer over part of that area. Structural Sedimentary Basin — A topographically low area in the Earth’s crust in which sediments have accumulated by transport via streams from the adjacent hills.
This electron micrograph (left) shows rock grains and the small pore spaces that provide groundwater storage in the Arapahoe aquifer. The scale bar is equivalent to .5mm (thinner than a fingernail).
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