Community Water System · PWS NN0403021
Cottonwood-Tselani NTUA
Operator location Ft Defiance, Navajo Nation - 12% of 66 violations are health-based (middle-third health share (≤ 23%)); groundwater source; 1,334 served per SDWIS.
- 1,334
- People served (this PWS)
- 66
- EPA violations (this PWS)
- 8
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Cottonwood-Tselani NTUA standing, mid SDWIS violation third
12% of 66 recorded violations are health-based - middle-third health share (≤ 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 12% is middle-third health share (≤ 23%). Population rank #16,951 of 29,740 among systems serving 500+.
The verdict
Cottonwood-Tselani NTUA lands in the middle third by violation volume (66), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is mid-pack at 1,334 (mid served population (≤ 3,309)). Health-based share is 12% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- #16,951 of 29,740
- Population · /systems
- #28 of 82
- Population · NN
- 66
- Total EPA violations on record
- 12%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Native American
- Connections
- 390
- School/Daycare
- No
- MCL Violations
- 8
- Monitoring Violations
- 38
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 5 | 2012 |
| Arsenic | MCL | 4 | 2013 |
| TTHM | MR | 3 | 2020 |
| Total Haloacetic Acids (HAA5) | MR | 3 | 2020 |
| Coliform (TCR) | MCL | 3 | 2011 |
| Stage 2 Disinfectants and Disinfection Byproducts Rule | MR | 2 | 2013 |
| Revised Total Coliform Rule | Other | 2 | 2016 |
| Gross Alpha, Excl. Radon and U | MR | 2 | 2004 |
| o-Dichlorobenzene | MR | 1 | 2005 |
| 1,2,4-Trichlorobenzene | MR | 1 | 2005 |
| Xylenes, Total | MR | 1 | 2005 |
| p-Dichlorobenzene | MR | 1 | 2005 |
| 1,1-Dichloroethylene | MR | 1 | 2005 |
| Trichloroethylene | MR | 1 | 2005 |
| 1,1,2-Trichloroethane | MR | 1 | 2005 |
| CHLOROBENZENE | MR | 1 | 2005 |
| Benzene | MR | 1 | 2005 |
| Toluene | MR | 1 | 2005 |
| Ethylbenzene | MR | 1 | 2005 |
| Styrene | MR | 1 | 2005 |
| Combined Radium (-226 and -228) | MR | 1 | 2005 |
| Nitrite | MR | 1 | 2010 |
| Tetrachloroethylene | MR | 1 | 2005 |
| 1,2-Dichloroethane | MR | 1 | 2005 |
| trans-1,2-Dichloroethylene | MR | 1 | 2005 |
| Carbon tetrachloride | MR | 1 | 2005 |
| 1,2-Dichloropropane | MR | 1 | 2005 |
| 1,1,1-Trichloroethane | MR | 1 | 2005 |
| Gross Alpha, Excl. Radon and U | MCL | 1 | 2010 |
| Vinyl chloride | MR | 1 | 2005 |
Violation Count vs. the National Corpus
Cottonwood-Tselani NTUA has 66 recorded EPA violations, 64% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 36% carry more. 12% of this system's own violations are health-based (8 of 66), and it ranks #16,951 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)
66 Around the middle fewer violations than 36% 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
Health-based violations on Cottonwood-Tselani NTUA
8 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for NN0403021.
Sources: EPA SDWIS
Nationwide peers
66 violations · 1,334 served: nearest cross-state SDWIS matches.
Cross-state systems near this violation count
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems near this population served
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Cottonwood-Tselani 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.