EPA Provides Drinking Water Assistance at Santee Sioux Nation near Niobrara, Nebraska
LENEXA, KAN. (SEPT. 12, 2025) – The U.S. Environmental Protection Agency (EPA) Region 7 deployed water experts and provided drinking water sampling assistance at the Santee Sioux Nation near Niobrara, Nebraska, on Sept. 8-10, 2025.
“EPA and Tribal leadership have mutual interests in ensuring clean and safe drinking water for the Santee Sioux Nation,” said EPA Region 7 Administrator Jim Macy. “We will continue to work together to resolve this issue.”
The Santee Sioux public drinking water utility routinely samples for bacterial contamination, including Escherichia coli (E.coli), and reports the findings to EPA. E. coli is a type of bacteria that lives in the intestines of people and animals and is commonly found in human and animal feces. Most strains of E. coli are harmless, but some can make people sick.
In early September, a series of samples at multiple locations throughout the Santee Sioux public drinking water system indicated the presence of total coliform bacteria — which is an indicator used to determine the adequacy of water treatment and the integrity of the distribution system — and one location showed E. coli that resulted in an exceedance of EPA’s maximum contaminant level (MCL) for the bacteria.
This MCL violation required the utility to issue a boil water advisory within 24 hours. On Sept. 5, the utility hand-delivered the advisory to its consumers, and over Sept. 6-7, and Tribal leadership took action to flush the water lines by opening fire hydrants and increase disinfection of the water system.
When an E. coli MCL violation occurs, water systems are required to conduct a “find and fix” approach that includes follow-up sampling and analyses. In addition, the Safe Drinking Water Act’s Revised Total Coliform Rule requires EPA — or a third party approved by EPA — to conduct a Level 2 Assessment within 30 days. This assessment is undertaken to identify and correct sanitary defects that may have contributed to the E. coli bacteria.
On Sept. 8, Region 7 mobilized two drinking-water scientists to the Santee Sioux Nation to begin the Level 2 Assessment. This team provided on-site assistance to the utility, conducting the necessary follow-up sampling and assisting with additional flushing activities. On Sept. 9, Region 7 deployed its Mobile Drinking Water Lab and two additional scientists to the site, which provided the utility with rapid, on-site sample analysis.
Next Steps
Preliminary sample findings from Sept. 10 and 11 did not indicate the presence of E.coli bacteria in the water lines, however, one of the two wells tested positive on Sept. 9. Out of an abundance of caution, the boil water advisory remains in place over the weekend, while EPA and Tribal leadership work together to identify potential sources of contamination around the well.
EPA is aware of the community concerns and has spoken with Tribal leadership regarding the safety of drinking water from the Santee Sioux public drinking water system. The agency will continue to coordinate with the water system as it works to resolve this issue, and will share the final sample results with the utility and community when they become available.
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