Public Outreach Fact Sheet

Regulation 32, discharger-specific variance for the City of Pueblo on the Arkansas River

Proposal for October 2023 Rulemaking

The Water Quality Control Commission will review a discharger-specific variance for selenium and sulfate that the Commission adopted in 2018. The City of Pueblo is asking the Commission to make no changes to this variance.

Pueblo has been addressing selenium and sulfate issues in the Arkansas River Basin for over 25 years. The sources of selenium and sulfate are natural. The geology under the city contains large amounts of selenium and sulfate. This causes high selenium and sulfate concentrations in the groundwater that enters the Pueblo sewer system. The Pueblo water reclamation facility removes about half of the selenium that enters from the sewer system, which benefits the environment. But the Pueblo water reclamation facility effluent concentrations still are higher than site-specific standards in the Arkansas River during wet conditions when groundwater infiltration increases. The concentrations of selenium and sulfate meet human health guidance, but selenium concentrations are higher than standards to protect fish, and sulfate concentrations may cause drinking water to taste bad.

Treatment for both selenium and sulfate is technologically difficult, expensive, and causes environmental harm. Pueblo serves disadvantaged communities with significantly lower income, higher unemployment, and higher poverty rates than any other large City in Colorado. Pueblo is also planning to meet multiple regulatory challenges and is planning large investments in its aging sewer collection system.

In 2018, the Commission adopted a variance for Pueblo for selenium and sulfate, based on the harsh and widespread impacts on the Pueblo community that would be caused by the cost of treating selenium and sulfate. The variance requires Pueblo to tackle its selenium and sulfate challenges by sealing its sewer mains in areas with the highest selenium and sulfate in the groundwater. The variance also requires Pueblo to look at whether there are affordable ways to reduce selenium and sulfate at the water reclamation facility. The variance lasts through 2028.

Since 2018, Pueblo has spent about $12 million to meet the variance requirements. Updated information shows that the variance still results in the best water quality that is feasible for the Pueblo community, and that the variance is still needed to prevent harmful economic impacts to disadvantaged communities in Pueblo.

Pueblo’s rulemaking proposal will keep the current variance. This will protect local communities from significant and unaffordable increases in sewer rates.

What waterbodies will be impacted?

Arkansas River from Fountain Creek to the Colorado Canal headgate near Avondale.

More Information, Questions, and Comments

To learn more, please contact Andra Ahrens, City of Pueblo Wastewater Director,
Email questions or comments to