Community Water System · PWS NN3503028
Toadlena NTUA
Operator location Ft Defiance, Navajo Nation - 34% of 197 violations are health-based (upper-third health share (> 23%)); groundwater source; 903 served per SDWIS.
- 903
- People served (this PWS) Smaller third of systems
- 197
- EPA violations (this PWS) Upper third of systems
- 67
- Health-based (this PWS) Upper third by health-based share
- No PFAS
- UCMR5 (this PWS) Tested, none detected
Toadlena NTUA standing, high SDWIS violation third
34% of 197 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 34% is upper-third health share (> 23%). UCMR5: UCMR5 tested, none detected. Population rank #20,926 of 29,740 among systems serving 500+.
The verdict
Toadlena NTUA sits in the upper third of the sitemap cohort by violation count (197), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (903; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 34% - most of this ledger is MCL or treatment-technique exceedance. UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #20,926 of 29,740
- Population · /systems
- #51 of 82
- Population · NN
- 197
- Total EPA violations on record
- 34%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
Based on EPA SDWIS violation history and UCMR5 PFAS testing only, not water taste, odor, infrastructure age, or contaminants outside the federally tracked set.
System Details
- System Type
- Community
- Owner Type
- Native American
- Connections
- 264
- School/Daycare
- No
- MCL Violations
- 67
- Monitoring Violations
- 95
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Arsenic | MCL | 65 | 2025 |
| Public Notice | Other | 16 | 2025 |
| Arsenic | MR | 11 | 2022 |
| Coliform (TCR) | MR | 8 | 2012 |
| Fluoride | MR | 4 | 2011 |
| Total Haloacetic Acids (HAA5) | MR | 3 | 2020 |
| Stage 2 Disinfectants and Disinfection Byproducts Rule | MR | 3 | 2013 |
| TTHM | MR | 3 | 2020 |
| CYANIDE | MR | 2 | 2011 |
| Coliform (TCR) | MCL | 2 | 2004 |
| Barium | MR | 1 | 2008 |
| Chromium | MR | 1 | 2008 |
| Nitrite | MR | 1 | 2010 |
| Selenium | MR | 1 | 2008 |
| Antimony, Total | MR | 1 | 2008 |
| Beryllium, Total | MR | 1 | 2008 |
| Thallium, Total | MR | 1 | 2008 |
| Endrin | MR | 1 | 2008 |
| Toxaphene | MR | 1 | 2008 |
| Diquat | MR | 1 | 2008 |
| OXAMYL | MR | 1 | 2008 |
| Carbofuran | MR | 1 | 2008 |
| 2,3,7,8-TCDD | MR | 1 | 2008 |
| Heptachlor | MR | 1 | 2008 |
| 2,4-D | MR | 1 | 2008 |
| 2,4,5-TP | MR | 1 | 2008 |
| Benzo(a)pyrene | MR | 1 | 2008 |
| Pentachlorophenol | MR | 1 | 2008 |
| 1,2,4-Trichlorobenzene | MR | 1 | 2008 |
| Chlordane | MR | 1 | 2008 |
Violation Count vs. the National Corpus
Toadlena NTUA has 197 recorded EPA violations, 85% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 15% carry more. 34% of this system's own violations are health-based (67 of 197), and it ranks #20,926 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)
197 Higher than most more violations than 85% 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
Toadlena NTUA 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.
Violation volume vs. health-based share
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 116 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFBA | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFOS | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFDA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 5/20/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFOA | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| 9Cl-PF3ONS | 5/20/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFNA | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| HFPO-DA | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFEESA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| ADONA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTrDA | 5/20/2024 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFPeS | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFMBA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTA | 5/20/2024 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFHpA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NEtFOSAA | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 5/20/2024 | <6.00 ppt | 6.00 ppt | Not Detected |
| NFDHA | 5/20/2024 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFHpS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 5/20/2024 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFPeS | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFMBA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 5/20/2024 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFBS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTA | 5/20/2024 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFDoA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NEtFOSAA | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 8:2 FTS | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 5/20/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 5/20/2024 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFDA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 5/20/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| ADONA | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 4:2 FTS | 5/20/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
Health-based violations on Toadlena NTUA
67 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for NN3503028.
Sources: EPA SDWIS
Nationwide peers
197 violations · 903 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.
Cross-state systems with smaller service footprints
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Toadlena NTUA
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Navajo Nation compares on the same EPA violation measures. Navajo Nation 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.
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.