Is Prairie Island water safe to drink?

Prairie Island (PWS ID: 055294502) has 188 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. EPA SDWIS lists this system's service population as 6,699 people using Groundwater sources.

How many people does Prairie Island serve?

EPA SDWIS reports that Prairie Island serves 6,699 people (this public water system's service population, not the municipal population of Welch or any other city). It is a Native American-owned system using Groundwater water sources with 110 service connections. The operator address is listed in Welch, EPA Region 5 — Tribal Water Systems.

What type of violations does Prairie Island have?

Prairie Island has 188 total violations: 0 health-based violations (MCL exceedances or treatment failures), 170 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.

Has PFAS been detected in Prairie Island water?

No. Prairie Island was tested for PFAS under the EPA's UCMR5 monitoring program and no PFAS contamination was detected.

What water source does Prairie Island use?

Prairie Island uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.

Where does this data come from?

All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.

Where does Prairie Island sit among U.S. public water systems?

According to EPA SDWIS population_served among sitemap-advertised systems (serving 500+), Prairie Island ranks #6,320 of 29,740 by people served, and #4 of 46 in EPA Region 5 — Tribal Water Systems. Ordinals use population_served DESC among systems serving 500+ (the sitemap cohort). See /methodology#corpus-placement.

How does Prairie Island's violation count compare nationally?

Prairie Island has 188 recorded EPA SDWIS violations, fewer than 16% of the 29,740 public water systems serving 500 or more people nationwide (the same sitemap cohort used for the corpus-placement ranking above). 84% of that cohort has fewer violations than Prairie Island. A system can have zero recorded violations and still be actively monitored, and a high violation count often reflects a system that reports thoroughly, not necessarily one with worse water.

States → EPA Region 5 — Tribal Water Systems

Community Water System · PWS 055294502

Prairie Island

Operator location Welch, EPA Region 5 — Tribal Water Systems - 0% of 188 violations are health-based (lower-third health share (≤ 1%)); groundwater source; 6,699 served per SDWIS.

Compiled by PlainWater · May 15, 2026

6,699
People served (this PWS) Larger third of systems: 188
EPA violations (this PWS) Upper third of systems: 0
Health-based (this PWS) Lower third by health-based share: No PFAS
UCMR5 (this PWS) Tested, none detected

Follow published updates (RSS)

Prairie Island standing, high SDWIS violation third

0% of 188 recorded violations are health-based - lower-third health share (≤ 1%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 0% is lower-third health share (≤ 1%). UCMR5: UCMR5 tested, none detected. Population rank #6,320 of 29,740 among systems serving 500+.

The verdict

Prairie Island sits in the upper third of the sitemap cohort by violation count (188), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is large (6,699; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is only 0% - almost all of this trail is monitoring or reporting. UCMR5 tested this system and reported no PFAS above the minimum reporting level.

#6,320 of 29,740
Population · /systems: #4 of 46
Population · 05: 188
Total EPA violations on record: 0%
Health-based (MCL / treatment failure)

Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.

C+

Water Safety Score

60/100

Prairie Island

Based on EPA SDWIS violation history and UCMR5 PFAS testing only, not water taste, odor, infrastructure age, or contaminants outside the federally tracked set.

Health-based violations A+

EPA SDWIS health-based violations on record (MCL, MRDL, treatment technique)

Monitoring & reporting violations F

188

Non-health SDWIS violations (monitoring, reporting, and other compliance)

PFAS contamination N/A

Tested, none detected

Highest PFAS compound level detected in UCMR5 testing

System Details

System Type: Community
Owner Type: Native American
Connections: 110
School/Daycare: No
MCL Violations: 0
Monitoring Violations: 170
Treatment Tech Violations: 0

Violation History

Contaminant violations recorded by EPA.

Contaminant	Category	Count	Latest
Coliform (TCR)	MR	17	1994
Nitrate	MR	8	2023
Lead and Copper Rule	MR	7	2023
Heptachlor	MR	4	2017
Barium	MR	3	2017
Cadmium	MR	3	2017
CYANIDE	MR	3	2017
Fluoride	MR	3	2017
Mercury	MR	3	2017
Nickel	MR	3	2017
Antimony, Total	MR	3	2017
o-Dichlorobenzene	MR	3	1996
1,1-Dichloroethylene	MR	3	1996
cis-1,2-Dichloroethylene	MR	3	1996
trans-1,2-Dichloroethylene	MR	3	1996
DICHLOROMETHANE	MR	3	1996
1,2-Dichloropropane	MR	3	1996
Ethylbenzene	MR	3	1996
Styrene	MR	3	1996
Toluene	MR	3	1996
1,2,4-Trichlorobenzene	MR	3	1996
1,1,1-Trichloroethane	MR	3	1996
1,1,2-Trichloroethane	MR	3	1996
Trichloroethylene	MR	3	1996
Vinyl chloride	MR	3	1996
Carbon tetrachloride	MR	3	1996
p-Dichlorobenzene	MR	3	1996
Xylenes, Total	MR	3	1996
Tetrachloroethylene	MR	3	1996
LEAD AND COPPER RULE REVISIONS	RPT	3	2024

Violation Count vs. the National Corpus

Prairie Island has 188 recorded EPA violations, 84% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 16% carry more. 0% of this system's own violations are health-based (0 of 188), and it ranks #6,320 of 29,740 by population served among that same cohort.

EPA violations vs. the national water-system corpus

Public water systems serving 500+ people (EPA SDWIS)

188 Higher than most more violations than 84% of 29,740 water systems

the national water-system corpus, bucketed by value

Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.

Source EPA SDWIS · 2026-05-15

How many violations vs. how serious, among peer systems

Prairie Island plotted against 29 peer public water systems (500+ people served), by total violation count (x) and the share of those violations that are health-based (y). The crosshair sits at this sample's own median on each axis. A high violation count does not automatically mean a serious record: most monitoring and reporting violations are minor, not health-based.

30 public water systems (500+ people served), EPA SDWIS current release.

How to read this

Each dot is one public water system; the highlighted dot is Prairie Island. A system to the right has more recorded violations; a system higher up has a larger share of those violations classified health-based rather than monitoring or reporting.

Rare but serious: few violations, but most of them are health-based.
Frequent, mostly paperwork: many violations, but mostly monitoring or reporting, not health-based.
Clean record: below-median on both counts, the tinted corner.

View all 30 systems as a list

City of Ballinger: 372 violations, 85% health-based
Nooksack Valley Water Association: 16 violations, 31% health-based
Montgomery Co RWD 12: 7 violations, 29% health-based
Irvin Water District #6: 11 violations, 27% health-based
Ticonderoga WD: 47 violations, 26% health-based
Pine Valley Plantation: 37 violations, 24% health-based
McLouth, City Of: 29 violations, 17% health-based
Kipling Oaks 1: 25 violations, 16% health-based
South Deerfield Water Supply District: 96 violations, 16% health-based
Sunset Ridge Water District: 82 violations, 15% health-based
Orange Water Dept: 136 violations, 14% health-based
Mount Pleasant Water Sys #1: 167 violations, 11% health-based
Lake Gibson Estates: 42 violations, 2% health-based
Benson Culinary Improvement District: 212 violations, 1% health-based
Conemaugh Twp Muni Auth: 567 violations, 1% health-based
Miccosukee Service Plaza: 0 violations, 0% health-based
Brazoria - Fort Bend Counties MUD 3: 0 violations, 0% health-based
Tanglewilde Thompson Place 600: 2 violations, 0% health-based
Center Water Co: 5 violations, 0% health-based
Spring Mills Elem School/Hvs: 9 violations, 0% health-based
Great Bend Industrial Park: 14 violations, 0% health-based
Glen Park Village: 19 violations, 0% health-based
Camp Is-Sho-Da: 22 violations, 0% health-based
Hamilton: 33 violations, 0% health-based
Town of Welaka: 54 violations, 0% health-based
Township of Blairstown Dpw: 61 violations, 0% health-based
McIntosh Water & Fire Pro Authority: 71 violations, 0% health-based
Clarkdale Municipal Water System: 114 violations, 0% health-based
Eureka Water Association: 273 violations, 0% health-based
Prairie Island: 188 violations, 0% health-based (this system)

PFAS Testing Results (UCMR5)

Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 58 samples detected PFAS.

Contaminant	Date	Result	MRL	Status
HFPO-DA	6/5/2023	<5.00 ppt	5.00 ppt	Not Detected
PFHxA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
9Cl-PF3ONS	6/5/2023	<2.00 ppt	2.00 ppt	Not Detected
11Cl-PF3OUdS	6/5/2023	<5.00 ppt	5.00 ppt	Not Detected
PFUnA	6/5/2023	<2.00 ppt	2.00 ppt	Not Detected
ADONA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFDoA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFDA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFOA	6/5/2023	<4.00 ppt	4.00 ppt	Not Detected
PFOS	6/5/2023	<4.00 ppt	4.00 ppt	Not Detected
PFBS	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFBA	6/5/2023	<5.00 ppt	5.00 ppt	Not Detected
NMeFOSAA	6/5/2023	<6.00 ppt	6.00 ppt	Not Detected
PFNA	6/5/2023	<4.00 ppt	4.00 ppt	Not Detected
6:2 FTS	6/5/2023	<5.00 ppt	5.00 ppt	Not Detected
4:2 FTS	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
8:2 FTS	6/5/2023	<5.00 ppt	5.00 ppt	Not Detected
PFMPA	6/5/2023	<4.00 ppt	4.00 ppt	Not Detected
PFPeA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFMBA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFEESA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
NFDHA	6/5/2023	<20.00 ppt	20.00 ppt	Not Detected
PFPeS	6/5/2023	<4.00 ppt	4.00 ppt	Not Detected
PFHpS	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFTA	6/5/2023	<8.00 ppt	8.00 ppt	Not Detected
NEtFOSAA	6/5/2023	<5.00 ppt	5.00 ppt	Not Detected
PFHpA	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFTrDA	6/5/2023	<7.00 ppt	7.00 ppt	Not Detected
PFHxS	6/5/2023	<3.00 ppt	3.00 ppt	Not Detected
PFTA	11/8/2023	<8.00 ppt	8.00 ppt	Not Detected
PFTrDA	11/8/2023	<7.00 ppt	7.00 ppt	Not Detected
NEtFOSAA	11/8/2023	<5.00 ppt	5.00 ppt	Not Detected
NMeFOSAA	11/8/2023	<6.00 ppt	6.00 ppt	Not Detected
4:2 FTS	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected
PFNA	1/24/2024	<4.00 ppt	4.00 ppt	Not Detected
PFOA	1/24/2024	<4.00 ppt	4.00 ppt	Not Detected
PFDA	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected
PFDoA	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected
PFHxA	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected
PFUnA	1/24/2024	<2.00 ppt	2.00 ppt	Not Detected
11Cl-PF3OUdS	1/24/2024	<5.00 ppt	5.00 ppt	Not Detected
9Cl-PF3ONS	1/24/2024	<2.00 ppt	2.00 ppt	Not Detected
ADONA	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected
HFPO-DA	1/24/2024	<5.00 ppt	5.00 ppt	Not Detected
PFBS	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected
6:2 FTS	1/24/2024	<5.00 ppt	5.00 ppt	Not Detected
PFHpA	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected
8:2 FTS	1/24/2024	<5.00 ppt	5.00 ppt	Not Detected
PFMPA	1/24/2024	<4.00 ppt	4.00 ppt	Not Detected
PFPeA	1/24/2024	<3.00 ppt	3.00 ppt	Not Detected

Health-based violations on Prairie Island

0 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for 055294502.

EPA SDWIS · PWS 055294502

Sources: EPA SDWIS

Nationwide peers

188 violations · 6,699 served: nearest cross-state SDWIS matches.

Cross-state systems with comparable violation load

Nearest cross-state community systems (500+ served) by total SDWIS violations on record.

4 peers

Cross-state systems with similar served population

Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).

4 peers

What to do with Prairie Island

Use this system's EPA-reported record as a starting filter, not a final verdict.

See how every tracked system in EPA Region 5 — Tribal Water Systems compares on the same EPA violation measures. EPA Region 5 — Tribal Water Systems systems
Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
Find and compare another public water system by name or PWSID. Search systems

EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Compiled by PlainWater, Drinking Water Quality Editorial Process · May 15, 2026

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.