Northern Colorado's newest reservoir to be filled following uranium detection in massive dam

Northern Colorado's newest reservoir, Chimney Hollow, will begin receiving water next week. The initial water moving into the reservoir is a major step for the project after such efforts came to a halt following the detection of mineralized uranium on the property.

Located west of Loveland, Chimney Hollow Reservoir is a project being built by Northern Water. After decades of planning and construction, Northern Water completed their massive dam in 2025. The dam is one of the largest dams built in America in recent history.

However, as the construction completed, researchers detected mineralized uranium in the dam which was built from rocks dug up from the same land that will soon be underwater.

After months of delays due to the discovery, Northern Water announced they are now ready to fill the reservoir with 1,500-acre feet of water next week. The water will be collected and analyzed in order to determine the uranium concentration.

Northern Water says they will not be releasing this water to the many cities and towns that bought into this project, at least for now.

However, via statement, the water provider said they will be conducting limited controlled releases of water from the dam in order to test equipment to assure it was built correctly. They said the water being used to conduct those tests will be fresh water from Pinewood Reservoir.

1,500-acre feet of water is minimal for the project, only accounting for around 2% of the reservoir's total projected capacity.

Though many have raised concerns over the detection of the mineralized uranium, some even questioning how it took so long to be detected, Northern Water says they are confident the project will move forward with safely managed water supply in Chimney Hollow.