Western Colorado has a long and complicated history with uranium mills, and one of the lasting impacts is the presence of uranium mill tailings, a sandy, radioactive byproduct left over from uranium processing. For decades, these materials were unknowingly used in the construction of homes, foundations, driveways, and fill dirt throughout Grand Junction and surrounding Mesa County.
Beginning in the 1970s, large cleanup programs removed tailings from thousands of properties. Even so, some properties today still contain elevated gamma radiation levels or remnants of tailings hidden under foundations or within older construction materials. Because of this, mill tailings testing has become a standard part of many real estate transactions in Grand Junction, Colorado.
Why Mill Tailings Matter
Uranium mill tailings can emit gamma radiation and radon gas, both of which may pose long-term health risks if present in high concentrations. While not every affected home is dangerous, it’s important to know whether a property has ever been evaluated.
Today, real estate agents, builders, and homeowners commonly request a Mill Tailings Report from the Colorado Department of Public Health & Environment (CDPHE) to determine whether radioactive materials were ever identified on a property.
Builders in Mesa County are also required to complete a Gamma Radiation Survey before issuing certain building permits to ensure the soil is safe for construction.
A Look Back: Tailings Use & Local Mill Sites
One of the largest local sites was the Climax uranium mill at Las Colonias, which operated from 1951 to 1970. During its lifetime, the mill produced more than 5,800 tons of uranium and over 2 million tons of tailings. Portions of these tailings were freely given away for public use in:
- Concrete and mortar
- Home foundations
- Road base and driveways
- Sidewalks and landscaping
- Farms and gardens
The practice officially ended on August 1, 1966, but no records were kept of where the materials were taken, making ongoing testing essential.
Cleanup Programs in Mesa County
Two major government programs addressed tailings contamination, though both were voluntary and not every homeowner participated:
1972 – Grand Junction Remedial Action Program (GJRAP)
A Colorado-run program targeting properties primarily in the Grand Junction area.
1978 – Uranium Mill Tailings Remedial Action Program (UMTRA)
A federal program managed by the U.S. Department of Energy.
UMTRA operated until 1998 and removed millions of tons of contaminated materials but did not always address exterior areas or all structural components.
Because standards evolved over time, some properties may still need updated surveys.
CDPHE Mill Tailings Services Today
Grand Junction continues to manage a state-run uranium mill tailings disposal facility, and CDPHE maintains a small team dedicated to testing, reporting, and public support. Services include:
Gamma Radiation Surveys
Required for building permits in Mesa County (not required in nearby counties).
Mill Tailings Reports
Often ordered during real estate transactions. CDPHE staff can explain the report or conduct an updated survey.
Report outcomes may include:
- No Indication of Tailings – No tailings found during evaluation.
- No Survey Performed – CDPHE believes risk is low even without a full survey.
- Tailings Indicated – Contamination may be present; further testing recommended.
- No Find Report – No records available (common for vacant land or older mobile homes).
- Disposal & Interim Storage Options – Tailings can be brought to local disposal facilities (usually free by appointment).
Most services remain free except printed records.
More info: www.CDPHE.colorado.gov/UMTS
Contaminated Properties & Cleanup Guidelines
Cleanup is not mandatory unless construction or permitting is involved. If tailings are identified:
- The property owner is responsible for removal costs.
- For contaminated concrete, CDPHE recommends removal in 3’ x 3’ sections.
- Safety measures include wearing dust masks, wetting materials during removal, washing hands/clothes, and limiting time in exposed areas.
- A Ludlum L-19 radiation meter is recommended to monitor levels during excavation.
- Interim storage is available locally, and permanent disposal occurs at the DOE-managed site.
In some cases, foundations can be encapsulated in shielding materials, but reports will always note that tailings exist, even if safely contained.
Other Western Colorado Areas Affected
Beyond Grand Junction, mill tailings were also found in communities such as:
- Rifle
- Gunnison
- Naturita
- Durango
- Fruita and Clifton (select areas)
What Homebuyers & Sellers Should Do
If you’re buying or selling a home in Grand Junction—or building new—consider taking these steps:
✔ Order a CDPHE Mill Tailings Report
This is especially important for homes built before the late 1970s. Order reports online at www.CDPHE.colorado.gov/UMTS.
✔ Ask whether previous surveys were conducted
Some properties have historical reports.
✔ Request updated testing if results are unclear
Testing is free, and modern equipment is more accurate.
✔ For new construction
Ensure a Gamma Radiation Survey has been completed before breaking ground.
Final Thoughts
Uranium mill tailings are part of Grand Junction’s history, but with today’s testing programs, updated surveys, and clear reporting from CDPHE, homeowners and buyers can make informed and confident decisions. Whether you’re purchasing an older property, developing land, or simply curious about your home’s history, understanding mill tailings is an important step in ensuring safety, transparency, and peace of mind in Mesa County real estate.
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