IRRIGATION SEASON WATER LEVEL CHANGES IN MUNICIPAL ARAPAHOE AQUIFER WELLS, DOUGLAS COUNTY, COLORADO

The Arapahoe aquifer of the Denver Basin aquifer system is one of the primary water sources used to meet municipal water demands in Douglas County, Colorado. Concentrated pumping from the Arapahoe aquifer has resulted in long-term and short-term water level changes. During the May through September irrigation season, over 150 feet of water level decline has been observed in non-pumping Arapahoe aquifer wells, with a corresponding water level rebound during winter months. Reduced late-summer aquifer water levels result in lower Arapahoe aquifer well yields.

Lawn irrigation accounts for roughly 50-percent of annual municipal water demand and irrigation season water level declines are the result of cumulative well-to-well interference during this high-demand period. Late in the irrigation season, public water supply systems that rely on the Arapahoe aquifer are confronted with meeting peak water demands while suffering a loss in Arapahoe aquifer well yield. Water storage, alternative water supplies, additional well drilling, demand management and other strategies may be implemented to address this challenge.