Well Water in Evergreen / Conifer / Bailey, Colorado

Fractured Rock Hydrogeology

Unlike the Denver Basin's sedimentary aquifers, foothills wells tap fractured crystalline bedrock — igneous and metamorphic rock where mineral crystals interlock with little to no open space between them. Porosity is less than 2%, and permeability is measured in hundredths of a millidarcy.

As one hydrogeologist put it: "Even granite has about 1 to 2 percent porosity — that's the storage tank. Fractures are merely the fast-delivery pipelines from the storage tank."

The practical result: most wells in the foothills have very low flow rates. Many homes use cistern systems — the well fills a storage tank slowly over time, and the house draws from the cistern. If your well produces 1-2 gallons per minute, a 1,500-gallon cistern gives you enough buffer for daily use. Without a cistern, a low-yield well can't keep up with peak demand (showers, laundry, dishwasher running simultaneously).

Recharge and Seasonal Variation

Foothills aquifers are recharged primarily by late winter and spring snowmelt. Average annual precipitation in the Conifer area is about 18 inches — modest for a mountain environment. This means water supply is directly linked to snowpack.

Water levels in fractured rock wells can fluctuate significantly by season. Wells may produce well in spring and early summer, then decline through late summer and fall. After drought years, some wells go dry entirely.

The Conifer Area Council's Water Team has been monitoring groundwater levels since concerns first surfaced in the late 1970s, when homeowners formed the Pleasant Park Neighborhood Association because they worried new development would impact their wells. Those concerns were well-founded.

Water Quality Concerns

The granitic and metamorphic geology of the foothills can contribute several contaminants to well water:

• Radon — uranium-bearing minerals in granite decay to produce radon, which dissolves in groundwater. Colorado mountain wells commonly test at 1,000 to 3,000 pCi/L, with levels above 5,000 pCi/L not unusual. See our radon guide.
• Uranium — naturally occurring in the crystalline bedrock
• Iron — causes rust staining; common in fractured rock wells
• Bacteria — shallow fracture systems are more vulnerable to surface contamination, especially after heavy rain or snowmelt events
• Hardness — varies widely depending on the specific minerals in the fracture zone your well taps

Alpine Building Performance in Denver performs well water testing across the foothills and Denver metro area, including for properties on private wells.

Development Pressure

Jefferson County's Evergreen Area Plan explicitly states that "new rezonings should allow only those uses that require little water, because the water supply is limited to wells." Sewage disposal capacity is also limited — most homes use septic systems, and the mountainous terrain constrains where systems can be placed.

Despite these constraints, development pressure continues. Every new home is another well drawing from the same limited fracture system. Unlike sedimentary aquifers with broad regional recharge, a fractured rock aquifer can be locally depleted by just a few additional wells in the same fracture network.

If you're buying property in the foothills, have the well tested and get a flow rate measurement before closing. A well that produces 0.5 gallons per minute is a very different situation than one producing 5 gallons per minute.