F0/100
Fort Defiance-Window Rock-St Michaels NTUA — Water Quality Report 2026
Serving 12,869 people · Arizona
Water Source
Groundwater
County
—
System ID
NN0403000
Violations
156
Contaminant Test Results
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Lead (90th percentile) | 0.002 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
2
Violations (last 5yr)
2
Unresolved
1
Health-Related
TIER 2Unresolved
Maximum contaminant level violation
When: February 1, 2025Rule: Total Coliform RuleEnforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Unresolved
Disinfection byproduct treatment technique failure
When: February 1, 2025Rule: Ground Water RuleEnforcement: Informal — resolved cooperativelyVerify on EPA.gov
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Frequently Asked Questions About Fort Defiance-Window Rock-St Michaels NTUA
Is Fort Defiance-Window Rock-St Michaels NTUA water safe to drink?
Fort Defiance-Window Rock-St Michaels NTUA water receives a grade of F (0/100), which is considered failing. 0 contaminant(s) exceed EPA legal limits and 156 violation(s) are on record. Customers may want to consider using a water filter.
What contaminants has Fort Defiance-Window Rock-St Michaels NTUA detected?
66 contaminants were tested in Fort Defiance-Window Rock-St Michaels NTUA's water. Notable contaminants include Lead (90th percentile). No contaminants exceed EPA legal limits. 1 exceed EPA health goals (MCLGs).
Does Fort Defiance-Window Rock-St Michaels NTUA have any EPA violations?
Yes, Fort Defiance-Window Rock-St Michaels NTUA has 156 EPA violation(s) on record, with the most recent in 2025. Violation types include TT, Other, MR. 22 are health-based violations.
How many people does Fort Defiance-Window Rock-St Michaels NTUA serve?
Fort Defiance-Window Rock-St Michaels NTUA serves approximately 12,869 people, Arizona. The system provides water to 1 community: Fort Defiance, Window Rock, St. Michaels.
What type of water does Fort Defiance-Window Rock-St Michaels NTUA provide?
Fort Defiance-Window Rock-St Michaels NTUA sources its water from groundwater. Groundwater is pumped from underground aquifers, which often provides natural filtration. The utility's system ID is NN0403000.
How does Fort Defiance-Window Rock-St Michaels NTUA compare to other utilities in Arizona?
Fort Defiance-Window Rock-St Michaels NTUA scores 0/100 with a grade of F (failing). This score suggests significant water quality concerns relative to other utilities. Visit our Arizona state page for a full comparison of water systems.