Physical Extent: The basin is a giant bowl stretching from Greeley in the north to Colorado Springs in the south, and from the front range to Limon.
Aquifer Layers: It consists of four separate "bowls" or aquifers stacked inside each other:
Dawson (Top layer)
Denver
Arapahoe
Laramie-Fox Hills (Bottom layer)
Aquifer Connectivity: While state officials believe the layers are sealed from each other, drilling logs do not show clear impermeable boundaries, and some tests show that pumping in one aquifer can affect another.
Geological Composition: The geology is not homogeneous; it consists of interlocking and overlapping layers of sand, gravel, sandstone, and claystone.
Water is often located in "pockets" within these layers.
Wells only 200 feet apart can have widely different static water levels.
2. Water Rights and Economics
"Paper Water" vs. "Wet Water": Having a water allocation or legal right is no guarantee that the physical water exists in that predicted amount.
Agriculture Impact: Statewide, agriculture uses 86% of Colorado's water. In the Denver Basin specifically, the breakdown is:
Agriculture: 62%
Municipal: 20%
Domestic (Private Wells): 12%
"Buy and Dry": When water rights are sold to developers, farmland is often left idle. Over 45,000 acres along the Arkansas River are now idle due to this principle.
The "Use it or Lose it" Rule: This can lead to waste, as owners may pour water onto the ground to maintain their claim and prevent it from being given to another user.
3. Local Water Usage and Sustainability
Residential Use:
An acre-foot is 326,500 gallons.
The average household uses 0.35 acre-feet (313 gallons) per day.
Return Rates: 90% of indoor water used with a septic system returns to the ground, whereas 100% of animal watering and 85% of irrigation water is lost to consumption or evaporation.
The 100 and 300-Year Rules:
State allocations are based on pumping aquifers dry in 100 years (initiated in 1973).
El Paso County initiated a 300-year rule in 1986, approving only 1/3 of the state's annual allocation to extend the life of the water supply.
Current Status: Water levels are declining in many areas, such as Castle Rock, where some wells drop up to 30 feet per year18. However, Black Forest wells have remained relatively steady.
4. Municipal and Developer Activity
Colorado Springs Utilities (CSU):
Primarily uses water from the Arkansas River and Western Slope snow runoff.
Policy is to use Denver Basin aquifer water only in emergencies.
Cherokee Metropolitan District:
Has purchased significant rights in the Black Forest but current test wells are producing poorly, suggesting commercial extraction may not be economically viable in some areas.
Future Risks: New developments like Sterling Ranch and The Ranch (totaling 7,400 homes) plan to use Denver Basin water, potentially straining resources more than the existing 6,600 private wells in Black Forest.
5. Proposed Common Sense Principles The committee suggests the following guidelines for future water management:
The Dawson aquifer should be reserved exclusively for private wells.
Water should not be pumped from one area of the basin to another2
All urban density developments should be required to use renewable water only.
All wells should be sited away from property boundaries to avoid pumping a neighbor's water.
Significant Facts About Water and the Denver Basin
