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Fort Defiance-Window Rock-St Michaels NTUA

PWS ID: NN0403000 · Ft Defiance, Navajo Nation 86504

Fort Defiance-Window Rock-St Michaels NTUA serves 12,869 people in Ft Defiance, Navajo Nation using Groundwater water sources. It has 248 recorded EPA violations, including 43 health-based violations. PFAS "forever chemicals" were detected in UCMR5 testing (1 compound found).

Water Quality Snapshot: Fort Defiance-Window Rock-St Michaels NTUA

Fort Defiance-Window Rock-St Michaels NTUA is a native american-owned community water system that delivers drinking water to 12,869 residents in Ft Defiance, Navajo Nation through 3,763 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 248 total violations for this system , of which 43 (17%) are health-based — meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 177 monitoring and reporting violations are on file. The most recent violation on record dates to 2025.

The most frequently cited contaminant at this system is TTHM, recorded in 19 violations (MCL, health-based). Under EPA's UCMR5 PFAS monitoring program, 1 PFAS compound was detected in samples collected from this system, with a maximum reported concentration of 138 ppt. PFAS are persistent synthetic chemicals linked to health effects at very low exposure levels.

Across Navajo Nation, EPA tracks 170 public water systems serving 167,275 people, with 29,535 cumulative violations and 1,366 health-based violations on record. About 100% of systems in the state carry at least one violation, and state-wide the average per system is 173.7 violations. Fort Defiance-Window Rock-St Michaels NTUA's 248 violations sit above the Navajo Nation average. Statewide, 13 of 13 UCMR5-tested systems have reported PFAS detections (100%). All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

PFAS Detected

1 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.

Population Served
12,869
Total Violations
248
Health-Based Violations
43
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Native American
Connections
3,763
School/Daycare
No
MCL Violations
41
Monitoring Violations
177
Treatment Tech Violations
2

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
TTHM MCL 19 2017
Total Haloacetic Acids (HAA5) MR 13 2018
TTHM MR 13 2018
Coliform (TCR) MCL 11 2014
Combined Uranium MCL 7 2013
Coliform (TCR) MR 7 2016
Public Notice Other 6 2025
cis-1,2-Dichloroethylene MR 5 2011
Xylenes, Total MR 5 2011
DICHLOROMETHANE MR 5 2011
o-Dichlorobenzene MR 5 2011
Vinyl chloride MR 5 2011
trans-1,2-Dichloroethylene MR 5 2011
1,2-Dichloropropane MR 5 2011
Tetrachloroethylene MR 5 2011
Toluene MR 5 2011
Ethylbenzene MR 5 2011
Styrene MR 5 2011
CHLOROBENZENE MR 5 2011
p-Dichlorobenzene MR 5 2011
ETHYLENE DIBROMIDE MR 4 2011
1,2-DIBROMO-3-CHLOROPROPANE MR 4 2011
1,2,4-Trichlorobenzene MR 3 2011
1,1-Dichloroethylene MR 3 2011
1,2-Dichloroethane MR 3 2011
1,1,1-Trichloroethane MR 3 2011
Carbon tetrachloride MR 3 2011
Trichloroethylene MR 3 2011
1,1,2-Trichloroethane MR 3 2011
Benzene MR 3 2011

PFAS Testing Results (UCMR5)

Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 12 of 420 samples detected PFAS.

Contaminant Date Result MRL Status
4:2 FTS 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFBS 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFHxS 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFNA 8/18/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFOS 8/18/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFOA 8/18/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFDA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFDoA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFHxA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFUnA 8/18/2025 <0.002 µg/L 0.002 µg/L Not Detected
11Cl-PF3OUdS 8/18/2025 <0.005 µg/L 0.005 µg/L Not Detected
9Cl-PF3ONS 8/18/2025 <0.002 µg/L 0.002 µg/L Not Detected
ADONA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
HFPO-DA 8/18/2025 <0.005 µg/L 0.005 µg/L Not Detected
6:2 FTS 8/18/2025 <0.005 µg/L 0.005 µg/L Not Detected
NFDHA 8/18/2025 <0.02 µg/L 0.02 µg/L Not Detected
NMeFOSAA 8/18/2025 <0.006 µg/L 0.006 µg/L Not Detected
NEtFOSAA 8/18/2025 <0.005 µg/L 0.005 µg/L Not Detected
PFTrDA 8/18/2025 <0.007 µg/L 0.007 µg/L Not Detected
PFTA 8/18/2025 <0.008 µg/L 0.008 µg/L Not Detected
lithium 8/18/2025 124.0000 µg/L 9 µg/L Detected
PFBA 8/18/2025 <0.005 µg/L 0.005 µg/L Not Detected
PFPeS 8/18/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFHpA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFEESA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFMBA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFPeA 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFMPA 8/18/2025 <0.004 µg/L 0.004 µg/L Not Detected
8:2 FTS 8/18/2025 <0.005 µg/L 0.005 µg/L Not Detected
PFHpS 8/18/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFDoA 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
11Cl-PF3OUdS 7/23/2024 <0.005 µg/L 0.005 µg/L Not Detected
PFUnA 7/23/2024 <0.002 µg/L 0.002 µg/L Not Detected
PFTA 7/23/2024 <0.008 µg/L 0.008 µg/L Not Detected
PFTrDA 7/23/2024 <0.007 µg/L 0.007 µg/L Not Detected
NEtFOSAA 7/23/2024 <0.005 µg/L 0.005 µg/L Not Detected
NMeFOSAA 7/23/2024 <0.006 µg/L 0.006 µg/L Not Detected
PFHxA 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
HFPO-DA 7/23/2024 <0.005 µg/L 0.005 µg/L Not Detected
PFDA 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
PFOA 7/23/2024 <0.004 µg/L 0.004 µg/L Not Detected
PFOS 7/23/2024 <0.004 µg/L 0.004 µg/L Not Detected
PFNA 7/23/2024 <0.004 µg/L 0.004 µg/L Not Detected
PFHxS 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
lithium 7/23/2024 31.5000 µg/L 9 µg/L Detected
PFEESA 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
PFHpA 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
PFBS 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
PFMBA 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected
PFHpS 7/23/2024 <0.003 µg/L 0.003 µg/L Not Detected

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records — or to file a complaint, request a Consumer Confidence Report, or check current monitoring status — go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Fort Defiance-Window Rock-St Michaels NTUA.

Federal Source of Truth

EPA SDWIS — Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID NN0403000 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Navajo Nation Drinking Water Authority

Navajo Nation's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find NN regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2025 Public Notice Other 6 SDWIS / NN0403000 / 7500
2025 Revised Total Coliform Rule TT 2 SDWIS / NN0403000 / 8000
2018 Total Haloacetic Acids (HAA5) MR 13 SDWIS / NN0403000 / 2456
2018 TTHM MR 13 SDWIS / NN0403000 / 2950
2018 Nitrate MR 2 SDWIS / NN0403000 / 1040
2018 Nitrite MR 2 SDWIS / NN0403000 / 1041
2017 TTHM MCL 19 SDWIS / NN0403000 / 2950
2016 Coliform (TCR) MR 7 SDWIS / NN0403000 / 3100
2016 Revised Total Coliform Rule Other 2 SDWIS / NN0403000 / 8000
2014 Coliform (TCR) MCL 11 SDWIS / NN0403000 / 3100
2013 Combined Uranium MCL 7 SDWIS / NN0403000 / 4006
2011 cis-1,2-Dichloroethylene MR 5 SDWIS / NN0403000 / 2380
2011 Xylenes, Total MR 5 SDWIS / NN0403000 / 2955
2011 DICHLOROMETHANE MR 5 SDWIS / NN0403000 / 2964
2011 o-Dichlorobenzene MR 5 SDWIS / NN0403000 / 2968

How Fort Defiance-Window Rock-St Michaels NTUA Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Fort Defiance-Window Rock-St Michaels NTUA Navajo Nation avg Federal benchmark
Total violations 248 173.7 SDWA compliance — any non-zero count is a recorded breach
Health-based violations 43 8 Indicates a contaminant exceeded a federal MCL
PFAS detection 1 compound 100% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 12,869 984 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 170 regulated public water systems in Navajo Nation.

Federal MCL reference — Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Fort Defiance-Window Rock-St Michaels NTUA water safe to drink? ▼
Fort Defiance-Window Rock-St Michaels NTUA (PWS ID: NN0403000) has 248 recorded violations in the EPA SDWIS database. PFAS contamination has been detected in UCMR5 testing, with 1 PFAS compound found. This system serves 12,869 people using Groundwater sources.
How many people does Fort Defiance-Window Rock-St Michaels NTUA serve? ▼
Fort Defiance-Window Rock-St Michaels NTUA serves 12,869 people in Ft Defiance, Navajo Nation. It is a Native American-owned system using Groundwater water sources with 3,763 service connections.
What type of violations does Fort Defiance-Window Rock-St Michaels NTUA have? ▼
Fort Defiance-Window Rock-St Michaels NTUA has 248 total violations: 43 health-based violations (MCL exceedances or treatment failures), 177 monitoring/reporting violations, and 2 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Fort Defiance-Window Rock-St Michaels NTUA water? ▼
Yes. UCMR5 testing detected 1 PFAS compound in Fort Defiance-Window Rock-St Michaels NTUA's water supply: lithium. PFAS are persistent "forever chemicals" that do not break down in the environment.
What water source does Fort Defiance-Window Rock-St Michaels NTUA use? ▼
Fort Defiance-Window Rock-St Michaels NTUA 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.

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Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. PFAS data from EPA UCMR5 monitoring program (2023-2025). This data is provided for informational purposes only.

Read our methodology — how this data is sourced, computed, and verified.

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Data sourced from $official public datasets. See our methodology for details. Retrieved and formatted by PlainWater Editorial