The Town of Superior receives most of its raw, untreated water from snow melt in the Upper Colorado River Basin as part of Northern Water's Big Thompson Project.
Northern Water has been working on the Chimney Hollow Reservoir project since 2021. Once complete, this project will help firm up water rights for several municipalities that rely on raw water from Northern Water, including Superior.
In 2023, a significant rain event prompted Northern Water to conduct emergency discharges from the cofferdam at Chimney Hollow Reservoir, located just west of Carter Lake in Larimer County. As required by environmental regulations, additional water quality testing was performed on the discharged water. These tests revealed elevated levels of uranium.
The United States Environmental Protection Agency (EPA) regulates uranium and has set the Maximum Contaminant Level (MCL) at 30 micrograms per liter (µg/L), or 30 parts per billion.
Northern Water has notified all project participants of the findings and published the information on their website. For more information on the findings, please read through this Frequently Asked Questions document from Northern Water discussing uranium at the Chimney Hollow Reservoir Site.
Please note: Northern Water is committed to reducing uranium levels below the EPA's MCL before releasing water from the reservoir. No water will be delivered from Chimney Hollow Reservoir until all assessments are complete, and filling is on hold while they develop a mitigation plan.
For our Town, this means we anticipate the need to treat for some level of uranium in the future. Fortunately, our water treatment plant is equipped to remove uranium to levels well below the MCL. We continue to monitor the situation closely and are actively working with Northern Water specialists to resolve the issue.
Questions? Email the Town's Public Works and Utilities Department.
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