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PFAS in drinking water: Tribal water systems, EPA Region 5

EPA's UCMR 5 data lists water systems on tribal lands by EPA region (Region 5) rather than by state.

EPA UCMR 5 results for 13 public water systems. 1 had at least one PFAS detected; 0 had a highest single PFOA or PFOS result above 4.0 ppt.

UCMR 5 is a one-time EPA monitoring program, not a compliance determination. The values shown are the highest single sample result at any of the system's sampling points; one result above 4.0 ppt does not mean the system violates the PFAS rule, which is judged on running annual averages under separate compliance monitoring. Results describe the public water system, not an individual home.

Water systemServesPFOA max (ppt)PFOS max (ppt)PFAS detected
East Bay Water Works
055293603		NDND0
Hannahville Community
055293611		NDND0
Keshena
055295508		NDND0
Lac Du Flambeau
055295401		NDND1
Little River Tribal Water System
055293702		NDND0
Lower Sioux
055294503		NDND0
Mt. Pleasant
055293201		NDND0
Oneida #1 Or Site #1
055295703		NDND0
Prairie Island
055294502		NDND0
Saganing
050593203		NDND0
Sioux Trail
055294506		NDND0
South-Central Water System
055295003		NDND0
Vineland
055294301		NDND0

ND = not detected (below the 4 ppt UCMR 5 reporting level). Values are the highest single sample result, not an annual average.

Source: EPA UCMR 5 final occurrence data (EPA page last updated 2026-08-28; samples collected January 2023 – December 2025) ↗.

PFAS disclaimer: PFAS results are copied from EPA's UCMR 5 dataset and describe samples taken at a public water system's entry points between 2023 and 2025, not water at any specific address. Levels may have changed since sampling (for example, after new treatment). “Not detected” means below EPA's UCMR 5 minimum reporting level, not zero. This is not a compliance determination or a water test. Contact your water utility for current information.