OF-23-08 Baseline Radiological Study Year 2: Gunnison County, Colorado


Funded through a grant from the Colorado Department of Public Health & Environment (CDPHE) the CGS is conducting a five-year baseline study of naturally occurring radionuclides and metals in groundwater samples obtained from privately owned residential water wells throughout Colorado. This report presents the methodology and available results from the second year of the study (2023) that focused on Gunnison County in west-central Colorado. Digital PDF download. OF-23-08D

From the report:

Gunnison County is predominately rural with only one city (Gunnison), and four towns (Crested Butte, Mount Crested Butte, Pitkin, and Marble). Gunnison is the county seat and much of the population is centered in this area. This county was selected for Year 2 of this study based on known deposits of uranium and to a lesser extent thorium within vein deposits, which were historically mined predominately in the southeastern portion of the county. Additionally, throughout the county there are both energy/alloy metal and industrial mineral and precious and base metal mining districts with some overlap. The energy/alloy metal and industrial minerals mining districts were sources for uranium, thorium, beryllium, columbium-tantalum, feldspar, gold, iron, lithium, marble, mercury, mica, molybdenum, niobium, perlite, rare earth elements, silver, sulfur, tungsten, and vanadium. The precious and base metal mining districts were sources for arsenic, copper, gold, iron, lead, manganese, molybdenum, silver, tungsten, and zinc. Five districts with known radioactive minerals include the Big Red Claims (part of or near Whitepine), Cochetopa, Marshal Pass, Powderhorn, and Quartz Creek Pegmatite whose location is shown in Figure 1. These deposits were associated with exposed Proterozoic crystalline and Paleozoic sedimentary rocks that are part of the Laramide Sawatch Uplift.