Community Water System · PWS NN3500261
Twin Lakes NTUA
Ft Defiance, Navajo Nation 86504 - drinking water served from groundwater sources to 1,833 people, tracked in EPA SDWIS and UCMR5.
- 1,833
- People served
- 93
- EPA violations
- 7
- Health-based
- Untested
- UCMR5 result
The verdict
EPA records 93 drinking-water violations at Twin Lakes NTUA, 8% of them health-based - below the Navajo Nation per-system average.
- 93
- Total EPA violations on record
- 8%
- Health-based (MCL / treatment failure)
- 1,833
- People served by this system
- N/A
- PFAS compounds detected (UCMR5)
Water Quality Snapshot: Twin Lakes NTUA
Twin Lakes NTUA is a native american-owned community water system that delivers drinking water to 1,833 residents in Ft Defiance, Navajo Nation through 536 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 93 total violations for this system , of which 7 (8%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 77 monitoring and reporting violations are on file. The most recent violation on record dates to 2020.
The most frequently cited contaminant at this system is Coliform (TCR), recorded in 9 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.
Across Navajo Nation, EPA tracks 170 public water systems serving 167,275 people, with 29,535 cumulative violations and 1,366 health-based violations on record. About 100% of systems in the state carry at least one violation, and state-wide the average per system is 173.7 violations. Statewide, 13 of 13 UCMR5-tested systems have reported PFAS detections (100%).
Twin Lakes NTUA's 93 violations sit below the Navajo Nation average.
All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.
System Details
- System Type
- Community
- Owner Type
- Native American
- Connections
- 536
- School/Daycare
- No
- MCL Violations
- 3
- Monitoring Violations
- 77
- Treatment Tech Violations
- 4
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 9 | 2014 |
| Total Haloacetic Acids (HAA5) | MR | 9 | 2020 |
| TTHM | MR | 9 | 2020 |
| Nitrite | MR | 4 | 2014 |
| Revised Total Coliform Rule | TT | 4 | 2016 |
| CYANIDE | MR | 3 | 2008 |
| Mercury | MR | 3 | 2008 |
| 2,3,7,8-TCDD | MR | 3 | 2011 |
| Coliform (TCR) | MCL | 3 | 2015 |
| Barium | MR | 3 | 2008 |
| Nitrate | MR | 3 | 2014 |
| Fluoride | MR | 3 | 2008 |
| Stage 2 Disinfectants and Disinfection Byproducts Rule | MR | 3 | 2013 |
| Gross Alpha, Excl. Radon and U | MR | 2 | 2005 |
| Revised Total Coliform Rule | Other | 2 | 2016 |
| 1,2,4-Trichlorobenzene | MR | 1 | 2005 |
| Xylenes, Total | MR | 1 | 2005 |
| DICHLOROMETHANE | MR | 1 | 2005 |
| o-Dichlorobenzene | MR | 1 | 2005 |
| p-Dichlorobenzene | MR | 1 | 2005 |
| Vinyl chloride | MR | 1 | 2005 |
| trans-1,2-Dichloroethylene | MR | 1 | 2005 |
| 1,2-Dichloroethane | MR | 1 | 2005 |
| 1,1,1-Trichloroethane | MR | 1 | 2005 |
| Carbon tetrachloride | MR | 1 | 2005 |
| 1,2-Dichloropropane | MR | 1 | 2005 |
| Trichloroethylene | MR | 1 | 2005 |
| 1,1,2-Trichloroethane | MR | 1 | 2005 |
| CHLOROBENZENE | MR | 1 | 2005 |
| Benzene | MR | 1 | 2005 |
Verify This Water System
The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Twin Lakes NTUA.
EPA SDWIS, Federal Reports
EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:
View PWS ID NN3500261 on SDWISSource: EPA SDWIS Federal Reports Search
Navajo Nation Drinking Water Authority
Navajo Nation's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.
Find NN regulator via EPA SDWISViolation Timeline
Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.
| Year (latest) | Contaminant | Category | Count | EPA Record |
|---|---|---|---|---|
| 2020 | Total Haloacetic Acids (HAA5) | MR | 9 | SDWIS / NN3500261 / 2456 |
| 2020 | TTHM | MR | 9 | SDWIS / NN3500261 / 2950 |
| 2016 | Revised Total Coliform Rule | TT | 4 | SDWIS / NN3500261 / 8000 |
| 2016 | Revised Total Coliform Rule | Other | 2 | SDWIS / NN3500261 / 8000 |
| 2015 | Coliform (TCR) | MCL | 3 | SDWIS / NN3500261 / 3100 |
| 2014 | Coliform (TCR) | MR | 9 | SDWIS / NN3500261 / 3100 |
| 2014 | Nitrite | MR | 4 | SDWIS / NN3500261 / 1041 |
| 2014 | Nitrate | MR | 3 | SDWIS / NN3500261 / 1040 |
| 2013 | Stage 2 Disinfectants and Disinfection Byproducts Rule | MR | 3 | SDWIS / NN3500261 / 0600 |
| 2011 | 2,3,7,8-TCDD | MR | 3 | SDWIS / NN3500261 / 2063 |
| 2008 | CYANIDE | MR | 3 | SDWIS / NN3500261 / 1024 |
| 2008 | Mercury | MR | 3 | SDWIS / NN3500261 / 1035 |
| 2008 | Barium | MR | 3 | SDWIS / NN3500261 / 1010 |
| 2008 | Fluoride | MR | 3 | SDWIS / NN3500261 / 1025 |
| 2005 | Gross Alpha, Excl. Radon and U | MR | 2 | SDWIS / NN3500261 / 4000 |
How Twin Lakes NTUA Compares
Cross-reference this system's record against state averages and the federal MCL framework for context.
| Metric | Twin Lakes NTUA | Navajo Nation avg | Federal benchmark |
|---|---|---|---|
| Total violations | 93 | 173.7 | SDWA compliance, any non-zero count is a recorded breach |
| Health-based violations | 7 | 8 | Indicates a contaminant exceeded a federal MCL |
| PFAS detection | None | 100% | EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt |
| Population served | 1,833 | 984 | Sizing context for compliance burden |
Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 170 regulated public water systems in Navajo Nation.
Federal MCL reference, Safe Drinking Water Act thresholds ▼
| Contaminant | Federal MCL / Action Level | Note |
|---|---|---|
| Lead | 0 mg/L (Action Level: 0.015 mg/L) | Lead and Copper Rule treatment technique |
| Arsenic | 0.010 mg/L (10 ppb) | Health-based MCL since 2006 |
| Total Coliform | Treatment technique (RTCR) | Indicator organism, monitoring trigger |
| PFOA / PFOS (PFAS) | 4.0 ppt each (final 2024 rule) | Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026) |
| Nitrate (as N) | 10 mg/L | Acute health risk for infants |
Frequently Asked Questions
Is Twin Lakes NTUA water safe to drink? ▼
How many people does Twin Lakes NTUA serve? ▼
What type of violations does Twin Lakes NTUA have? ▼
Has PFAS been detected in Twin Lakes NTUA water? ▼
What water source does Twin Lakes NTUA use? ▼
Where does this data come from? ▼
Read our methodology - how this data is sourced, computed, and verified.
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.