Community Water System · PWS CO0112300
Costilla County WS
Operator location San Luis, Colorado - smaller served population (≤ 999) at 561 people served; 116 SDWIS violations on record from groundwater sources.
- 561
- People served (this PWS)
- 116
- EPA violations (this PWS)
- 5
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Costilla County WS standing, high SDWIS violation third
561 people served (SDWIS) - smaller served population (≤ 999). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 4% is middle-third health share (≤ 23%). Population rank #27,209 of 29,740 among systems serving 500+.
The verdict
Costilla County WS sits in the upper third of the sitemap cohort by violation count (116), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (561; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 4% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- #27,209 of 29,740
- Population · /systems
- #505 of 551
- Population · CO
- 116
- Total EPA violations on record
- 4%
- 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
- Local
- Connections
- 396
- County
- Costilla
- School/Daycare
- No
- MCL Violations
- 4
- Monitoring Violations
- 110
- Treatment Tech Violations
- 1
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 9 | 2001 |
| Gross Alpha, Excl. Radon and U | MR | 8 | 2016 |
| Lead and Copper Rule | MR | 6 | 2006 |
| Nitrate | MR | 5 | 1993 |
| p-Dichlorobenzene | MR | 4 | 2016 |
| Trichloroethylene | MR | 4 | 2016 |
| Carbon tetrachloride | MR | 4 | 2016 |
| 1,2-Dichloroethane | MR | 4 | 2016 |
| 1,1-Dichloroethylene | MR | 4 | 2016 |
| 1,1,1-Trichloroethane | MR | 4 | 2016 |
| Benzene | MR | 4 | 2016 |
| Coliform (TCR) | MCL | 4 | 2002 |
| cis-1,2-Dichloroethylene | MR | 3 | 2016 |
| DICHLOROMETHANE | MR | 3 | 2016 |
| trans-1,2-Dichloroethylene | MR | 3 | 2016 |
| 1,1,2-Trichloroethane | MR | 3 | 2016 |
| CHLOROBENZENE | MR | 3 | 2016 |
| Ethylbenzene | MR | 3 | 2016 |
| Styrene | MR | 3 | 2016 |
| Combined Radium (-226 and -228) | MR | 3 | 2016 |
| TTHM | MR | 3 | 2022 |
| Total Haloacetic Acids (HAA5) | MR | 3 | 2022 |
| 1,2-Dichloropropane | MR | 3 | 2016 |
| Di(2-ethylhexyl) phthalate | MR | 3 | 2020 |
| Tetrachloroethylene | MR | 3 | 2016 |
| Vinyl chloride | MR | 3 | 2016 |
| o-Dichlorobenzene | MR | 3 | 2016 |
| Xylenes, Total | MR | 3 | 2016 |
| 1,2,4-Trichlorobenzene | MR | 3 | 2016 |
| Toluene | MR | 3 | 2016 |
Violation Count vs. the National Corpus
Costilla County WS has 116 recorded EPA violations, 76% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 24% carry more. 4% of this system's own violations are health-based (5 of 116), and it ranks #27,209 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)
116 Higher than most more violations than 76% 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
Population served record for Costilla County WS
EPA SDWIS lists 561 people served and 396 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS · Colorado Department of Public Health and Environment, Water Quality Control
Nationwide peers
116 violations · 561 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 Costilla County WS
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Colorado compares on the same EPA violation measures. Colorado 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.