Non-Transient Non-Community Water System · PWS NN0400822
Twin Arrows NTUA
Operator location Ft Defiance, Navajo Nation - 0% of 90 violations are health-based (lower-third health share (≤ 1%)); groundwater source; 25 served per SDWIS.
- 25
- People served (this PWS)
- 90
- EPA violations (this PWS)
- 0
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Twin Arrows NTUA standing, high SDWIS violation third
0% of 90 recorded violations are health-based - lower-third health share (≤ 1%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 0% is lower-third health share (≤ 1%).
The verdict
Twin Arrows NTUA sits in the upper third of the sitemap cohort by violation count (90), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (25; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is only 0% - almost all of this trail is monitoring or reporting. No UCMR5 PFAS test appears for this system in this extract.
- 90
- Total EPA violations on record
- 0%
- Health-based (MCL / treatment failure)
- 25
- People served by this PWS (SDWIS)
- N/A
- PFAS compounds detected (UCMR5)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Non-Transient Non-Community
- Owner Type
- Native American
- Connections
- 1
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 79
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Diquat | MR | 15 | 2015 |
| Endothall | MR | 15 | 2015 |
| Glyphosate | MR | 15 | 2015 |
| 2,3,7,8-TCDD | MR | 15 | 2015 |
| Xylenes, Total | MR | 10 | 2020 |
| TTHM | MR | 3 | 2015 |
| Total Haloacetic Acids (HAA5) | MR | 3 | 2015 |
| Revised Total Coliform Rule | Other | 2 | 2016 |
| Stage 2 Disinfectants and Disinfection Byproducts Rule | MR | 2 | 2013 |
| Coliform (TCR) | MR | 1 | 2013 |
Violation Count vs. the National Corpus
Twin Arrows NTUA has 90 recorded EPA violations, 71% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 29% carry more. 0% of this system's own violations are health-based (0 of 90), and it ranks unranked by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
90 Around the middle fewer violations than 29% 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 Twin Arrows NTUA
0 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for NN0400822.
Sources: EPA SDWIS
Nationwide peers
90 violations · 25 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.
What to do with Twin Arrows 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.