More than 70 percent of the municipal water supply in the south Denver metropolitan area is provided by groundwater, and homeowners in rural areas depend solely on self-supplied groundwater for water supply. Increased groundwater withdrawal to meet the demand of the rapidly growing population is causing water levels to decline. The U.S. Geological Survey, in cooperation with the Rural Water Authority of Douglas County, began a study in 2011 to assess the groundwater resources of the Denver Basin aquifers within Douglas County, Colorado. The primary purpose of this study was to monitor changes in the groundwater levels of the bedrock aquifers of the Denver Basin within rural Douglas County. To better assess the water resources of the Denver Basin bedrock aquifers, a groundwater monitoring network was established in 2011. More than 500 manual and 213,900 automated water-level measurements collected from the 36 domestic-well network between April 2011 and June 2013 showed water-level declines in all aquifers.
Manual and automated (time-series) water-level data collection from these sites between 2011 and 2013 showed water level declines in 36 wells. Over the 2-year monitoring period, average declines of approximately 0.4 foot per year were observed in the upper Dawson aquifer, declines of over 2.6 feet per year were observed in the lower Dawson aquifer, declines of about 3.2 feet per year were observed in the Denver aquifer, declines of about 1.9 feet per year were observed in the Arapahoe aquifer, and declines of about 9.9 feet per year were observed in the Laramie-Fox Hills aquifer.
