Public water system · NN0403000
ActiveFort Defiance-Window Rock-St Michaels NTUA
At a glance
Fort Defiance-Window Rock-St Michaels NTUA (PWSID NN0403000) is an active community water system in Arizona. It reports serving 12,869 people through 3,763 service connections. Its primary water source is groundwater, and EPA lists it as Native American-owned. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in February 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
12,869
Service connections
3,763
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Fort Defiance-Window Rock-St Michaels NTUA compare with other water systems in Arizona?
By EPA's size categories, Fort Defiance-Window Rock-St Michaels NTUA is a large system (10,001 to 100,000 people). Across Arizona, the 1,769 active systems average 4,369 people each. Nationally, the average active community water system reports serving 6,703 people, so Fort Defiance-Window Rock-St Michaels NTUA is about twice that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Arizona has 936 active community water systems, 53% of the state's 1,769 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,612 Arizona systems (91%) list groundwater as their primary source.
Who owns and regulates Fort Defiance-Window Rock-St Michaels NTUA?
EPA lists Fort Defiance-Window Rock-St Michaels NTUA as Native American-owned. The NN state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act.
Does Fort Defiance-Window Rock-St Michaels NTUA have drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in February 2025. The violations listed here began between January 2017 and February 2025. By type: 6 monitoring and reporting, 3 public notice, recordkeeping or other, 2 contaminant level above the legal limit and 1 required treatment not met. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (4 of them). EPA lists 10 as resolved and 2 as unaddressed. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-02-01 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Unaddressed |
| 2025-02-01 | Required treatment not metTreatment Technique, Level 1 Assessment (RTCR) · code 2A | Revised Total Coliform Rulecode 8000 | Yes | Resolved |
| 2024-10-01 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Unaddressed |
| 2024-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2018-07-01 | Monitoring and reportingMonitoring, Routine (IDSE) · code 30 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2018-07-01 | Monitoring and reportingMonitoring, Routine (IDSE) · code 30 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2018-04-01 | Monitoring and reportingMonitoring, Routine (IDSE) · code 30 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2018-04-01 | Monitoring and reportingMonitoring, Routine (IDSE) · code 30 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2018-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2018-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2017-01-01 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2017-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
The 12 most recent violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Fort Defiance-Window Rock-St Michaels NTUA: frequently asked questions
Who runs Fort Defiance-Window Rock-St Michaels NTUA?
Fort Defiance-Window Rock-St Michaels NTUA (PWSID NN0403000) is a community water system Native American-owned. It is regulated by the NN state drinking water program.
How many people does Fort Defiance-Window Rock-St Michaels NTUA serve?
Fort Defiance-Window Rock-St Michaels NTUA reports serving 12,869 people through 3,763 service connections in Arizona.
Where does Fort Defiance-Window Rock-St Michaels NTUA get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Fort Defiance-Window Rock-St Michaels NTUA have any drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in February 2025. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Fort Defiance-Window Rock-St Michaels NTUA's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in February 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the NN state drinking water program.
Where can I find Fort Defiance-Window Rock-St Michaels NTUA's water quality report?
As a community water system, Fort Defiance-Window Rock-St Michaels NTUA must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Arizona
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Phoenix City of | Maricopa | 1,695,000 | Community | Surface water |
| Tucson City of | Pima | 732,906 | Community | Groundwater |
| Mesa City of | Maricopa | 466,000 | Community | Surface water |
| Gilbert, Town of | Maricopa | 247,600 | Community | Surface water |
| Chandler City of | Maricopa | 247,328 | Community | Surface water |
| Scottsdale City of | Maricopa | 241,361 | Community | Surface water |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Fort Defiance-Window Rock-St Michaels NTUA, PWSID NN0403000, Arizona”, https://aquacensus.com/water-systems/arizona/fort-defiance-window-rock-st-michaels-ntua-nn0403000 (data as of October 1, 2026).