Project Managers to Investigate Uranium Mitigation Strategies

Chimney Hollow Reservoir Project managers are investigating strategies to mitigate the presence of mineralized uranium that is anticipated to be present in the first fill of the reservoir. 

Mineralized uranium was detected in water samples taken from behind the cofferdam at the site following a series of major precipitation events in summer 2023. Further testing through 2024 identified the source of the minerals as being the granitic rock being quarried on the west side of the reservoir for placement in the rockfill shell of the asphalt-core dam. The low-level uranium minerals detected were not anticipated to be the result of leached material at the site. 

During dam testing and first fill of the reservoir starting later this summer and continuing through 2027, no releases of water from Chimney Hollow Reservoir are expected. Ongoing monitoring of water quality at the reservoir will help managers develop a mitigation strategy that could include treatment and dilution with the significant sources of other water present in the infrastructure nearby. 

As more information becomes available, Northern Water will share it with project participants, partner agencies and the public.