Community Water System · PWS CA5210005
Rio Alto Water District
Operator location Cottonwood, California - 50% of 8 violations are health-based (upper-third health share (> 23%)); groundwater source; 3,329 served per SDWIS.
- 3,329
- People served (this PWS)
- 8
- EPA violations (this PWS)
- 4
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Rio Alto Water District standing, low SDWIS violation third
50% of 8 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 50% is upper-third health share (> 23%). Population rank #9,888 of 29,740 among systems serving 500+.
The verdict
Rio Alto Water District is in the lower third by violation count (8; lower-third violation load (≤ 21 violations)). A low count does not mean the system is unmonitored - monitoring and reporting violations still appear in SDWIS. Population served is large (3,329; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 50% - most of this ledger is MCL or treatment-technique exceedance. No UCMR5 PFAS test appears for this system in this extract.
- #9,888 of 29,740
- Population · /systems
- #741 of 1,701
- Population · CA
- 8
- Total EPA violations on record
- 50%
- 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
- 1,433
- County
- Tehama
- School/Daycare
- No
- MCL Violations
- 4
- Monitoring Violations
- 4
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 4 | 2015 |
| Coliform (TCR) | MR | 3 | 2012 |
| Lead and Copper Rule | MR | 1 | 1993 |
Violation Count vs. the National Corpus
Rio Alto Water District has 8 recorded EPA violations, 15% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 83% carry more. 50% of this system's own violations are health-based (4 of 8), and it ranks #9,888 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)
8 Among the lowest violation counts fewer violations than 83% 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 Rio Alto Water District
4 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for CA5210005.
Sources: EPA SDWIS · California State Water Resources Control Board, Division of Drinking Water
Nationwide peers
8 violations · 3,329 served: nearest cross-state SDWIS matches.
Cross-state systems with similarly light violation ledgers
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
- Mohegan Tribal Utility Authority EPA Region 1 — Tribal Water Systems 8violations
- Hannahville Community EPA Region 5 — Tribal Water Systems 8violations
- Quapaw Downstream Casino & Resort EPA Region 6 — Tribal Water Systems 8violations
- San Ildefonso Totavi EPA Region 6 — Tribal Water Systems 8violations
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Rio Alto Water District
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in California compares on the same EPA violation measures. California 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.