County consultant: Denver Basin aquifers broadly reliable now but warrant periodic review

El Paso County commissioners heard a technical review of the Denver Basin aquifers on Oct. 21 and were told the basin remains a usable but nonrenewable water resource that requires ongoing monitoring.

Consultant Bruce Lytle, now with Moore Engineering, told the Board of County Commissioners that long-term water-level records and geophysical logs show most monitoring and nonexempt production wells in El Paso County have water levels at or above the top of the named Denver Basin aquifers — Dawson, Denver, Arapahoe and Laramie/Fox Hills — although some local wells show partial dewatering and regional declines in pressure in parts of the Arapahoe.

"The Denver Basin really is not part of the hydrologic cycle," Lytle said, summarizing the geology and why recharge is minimal; the aquifer water was deposited millions of years ago and behaves like "a big bathtub" of largely nonrecharging supply. He added the state allocation method counts only saturated thickness and does not credit pressure held in confined sands.

Why it matters: the Denver Basin supplies municipal, district and irrigation wells across northern and eastern El Paso County. Lytle told commissioners the county’s local 300-year allocation approach provides an added layer of conservatism beyond the state’s 100-year allocation, and he recommended continuing the county’s monitoring approach rather than making immediate code or policy…