Well Water in Golden, Colorado

Jefferson County · Population ~20,400 · Aquifer: Municipal Clear Creek surface water; fractured crystalline-rock wells in the western foothills

Hardness: Moderately hard (~116 ppm municipal); variable in foothills wells

Golden's Water Is 100 Percent Clear Creek Surface Water

Golden holds some of the oldest and most senior direct-flow water rights on Clear Creek. Its supply is snowmelt-driven surface water: direct diversions from Clear Creek, storage in three mountain reservoirs (Upper Urad, Lower Urad, and Guanella), and trans-basin diversions through the Vidler and Jones Pass tunnels. The city's Drought Management Plan describes a "snowmelt-driven surface water hydrology" with no municipal Denver Basin production well field. The Golden Water Treatment Plant treats Clear Creek water; the Clear Creek watershed spans 575 square miles, nearly two-thirds of the upper watershed in the Arapaho and Roosevelt National Forests.

Foothills Wells: Fractured Granite and Radon

The private wells west of Golden sit in fractured crystalline-rock aquifer — Precambrian granite and metamorphic rock of the Front Range. Yields are low and fracture-dependent; two neighboring wells can produce completely different quantities of water. The signature water-quality concern is radon: Front Range granitic rock is uranium-bearing, and radon concentrates in well water there. A USGS study of Colorado granitic-rock aquifer wells found a median dissolved radon of 6,300 pCi/L (versus 795 pCi/L in volcanic rock); the EPA's proposed water standards are 300 pCi/L, or 4,000 with a multimedia mitigation program, though neither applies to private wells.

A local USGS and Jefferson County Health Department study (WRI 79-94, 1979) tested 26 domestic wells in the west-central Jeffco foothills (the Indian Hills area) and found 21 of 26 exceeded standards for one or more constituents — fluoride, nitrate plus nitrite, dissolved solids, iron, manganese, zinc, coliform bacteria, and radiation; gross alpha exceeded 15 pCi/L in 11 of the wells. Jefferson County Public Health lists natural radiation (uranium and radium) among documented private-well concerns in the county.

The Mining Legacy Upstream

The Central City / Clear Creek Superfund site (placed on the National Priorities List in 1983) covers the 400-square-mile upper Clear Creek watershed "extending from the Continental Divide to Golden." Roughly 90 years of hardrock gold and silver mining left arsenic and lead as the metals of human-health concern, along with acid mine drainage. Two water-treatment plants now operate on the creek. This affects Golden's source water more than the foothills wells, but it is the documented heavy-metals context for the whole Golden water system — and Golden's own source-water assessment candidly lists the Superfund sites and abandoned mines among potential contamination sources.

Golden's Municipal Water Quality

Golden treats Clear Creek water through settling, coagulation with ferric sulfate, sedimentation (removing about 90 percent of solids), six multimedia filters, pH adjustment, and chlorination. The 2023 Water Quality Report showed zero violations; UCMR testing found zero detections for all 29 PFAS chemicals in both raw and finished water; combined uranium was under 1.0 µg/L (limit 20); lead at the 90th percentile was 0 ppb; hardness averaged about 116 ppm (moderately hard) and TDS about 267 ppm.

What Golden Area Residents Should Know

If you're on City of Golden Water (the city proper): your water is treated Clear Creek surface water meeting all standards, with clean PFAS and lead results.

If you're on a private well in the western foothills (Indian Hills, Aspen Park, Tiny Town): radon is the priority — test for it, along with bacteria, nitrate, fluoride, gross alpha radiation, iron, manganese, and dissolved solids. See our testing guide and radon page, and our Evergreen / Conifer page for more on fractured-rock well issues common to this geology.