Community Water System · PWS NM3509723
San Ysidro Water Supply System
Operator location San Ysidro, New Mexico - 45% of 429 violations are health-based (upper-third health share (> 23%)); groundwater source; 166 served per SDWIS.
- 166
- People served (this PWS)
- 429
- EPA violations (this PWS)
- 193
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
San Ysidro Water Supply System standing, high SDWIS violation third
45% of 429 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 45% is upper-third health share (> 23%).
The verdict
San Ysidro Water Supply System sits in the upper third of the sitemap cohort by violation count (429), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (166; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 45% - most of this ledger is MCL or treatment-technique exceedance. No UCMR5 PFAS test appears for this system in this extract.
- 429
- Total EPA violations on record
- 45%
- Health-based (MCL / treatment failure)
- 166
- 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
- Community
- Owner Type
- Local
- Connections
- 96
- County
- Sandoval
- School/Daycare
- No
- MCL Violations
- 178
- Monitoring Violations
- 189
- Treatment Tech Violations
- 15
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Fluoride | MCL | 138 | 2024 |
| Arsenic | MR | 44 | 2022 |
| Total Haloacetic Acids (HAA5) | MR | 40 | 2023 |
| TTHM | MR | 39 | 2023 |
| Arsenic | MCL | 24 | 2023 |
| Coliform (TCR) | MR | 23 | 1998 |
| Consumer Confidence Rule | Other | 18 | 2021 |
| Lead and Copper Rule | MR | 18 | 2015 |
| TTHM | MCL | 13 | 2011 |
| Fluoride | MR | 12 | 2022 |
| Revised Total Coliform Rule | MON | 8 | 2020 |
| Groundwater Rule | TT | 8 | 2025 |
| Public Notice | Other | 5 | 2022 |
| Chlorine | MR | 4 | 2020 |
| Stage 1 Disinfectants and Disinfection Byproducts Rule | TT | 4 | 2012 |
| LEAD AND COPPER RULE REVISIONS | RPT | 3 | 2024 |
| LEAD AND COPPER RULE REVISIONS | TT | 3 | 2024 |
| Coliform (TCR) | MCL | 3 | 1999 |
| Nitrate-Nitrite | MR | 1 | 2006 |
Violation Count vs. the National Corpus
San Ysidro Water Supply System has 429 recorded EPA violations, 94% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 6% carry more. 45% of this system's own violations are health-based (193 of 429), 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)
429 Higher than most more violations than 94% 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 San Ysidro Water Supply System
193 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for NM3509723.
Sources: EPA SDWIS
Nationwide peers
429 violations · 166 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 San Ysidro Water Supply System
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in New Mexico compares on the same EPA violation measures. New Mexico 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.