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Mammoth Lakes, CA Tap Water Quality 2026

Water quality report for Mammoth Lakes, CA — PFAS, lead and copper results, violation history and state inspection findings from EPA SDWIS.

A look at Mammoth Lakes's drinking water using EPA enforcement records: violations, lead and copper results, PFAS sampling and state inspection findings.

Main Utility: Mammoth Cwd PWSID: CA2610001 Updated: 2026 Q2
✅

No federal limits exceeded on record

Lead was not detected and no violations are open. No PFAS was detected.

B

Mammoth Lakes earns a B for water quality

Graded on violations, lead, and PFAS, with state inspection findings.

Lead: not detected
PFAS tested, none detected
3 violations since 2015, 1 health-based
No violations currently open
Mammoth Lakes's lead level vs. all California community water systems
0 ppb5 ppb10 ppb15 ppb
Lead level: Not detected — 0% of the federal action level
✓ Lower lead than % of California utilities
Population Served
7142
~3818 connections
Water Source
Surface water
Drawn from surface water — SDWIS source code SW
Active Violations
0
3 since 2015, all resolved

Lead & Copper Testing

Lead (Pb)
90th percentile of tap samples collected across the distribution system
0% of EPA action level
Not detected
Action level: 15 ppb
Copper (Cu)
90th percentile of tap samples. SDWIS reports a copper figure only when a system exceeds the action level, so any value here is an exceedance.
107.7% of EPA action level
1,400 ppb
Action level: 1,300 ppb
Lead was not detected at the 90th percentile — the result fell below the laboratory detection limit. That is not the same as an absence of lead in every tap, and older homes with lead service lines can still show higher readings. Copper reached the action level here; a copper figure appears in SDWIS only when a system triggers it.

Contaminant Violations (2015–Present)

ContaminantTypeMeasuredLimitPeriodStatus
Total Haloacetic Acids (HAA5) MONITORING AND REPORTING — 0.060 mg/L 2023 Resolved
TTHM MONITORING AND REPORTING — 0.080 mg/L 2023 Resolved
Surface Water Treatment Rule TREATMENT TECHNIQUE — — 2016 Resolved
Understanding violation types MCL violations mean a contaminant exceeded the federal maximum limit — the most serious type.
TT (Treatment Technique) violations mean required treatment procedures weren't followed, but don't necessarily mean contamination occurred.

Violation History

3 violations are on record since 2015, of which 1 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Mammoth Cwd
PWSID CA2610001
Water source Surface water — Drawn from surface water — SDWIS source code SW
Population served 7,142
Service connections 3,818
Systems serving this area 1
Regulator State primacy agency
Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Mammoth Lakes tap water safe to drink? ▼
No federal limit is exceeded on record. No violations are currently open.
Does Mammoth Lakes water have PFAS? ▼
It was tested for the six regulated PFAS compounds and none were detected.
Who supplies water to Mammoth Lakes? ▼
Mammoth Cwd (PWSID CA2610001). Surface water. Drawn from surface water — SDWIS source code SW
When was this system last inspected? ▼
It was last inspected on 2024-06-26. No significant deficiencies were recorded.

What Should Mammoth Lakes Residents Do?

1
Read your annual water report
Your supplier publishes a Consumer Confidence Report each July covering the prior year.
2
Check for a lead service line
Lead reaches tap water mainly through service lines and household plumbing. Suppliers now publish an inventory identifying lead lines.
3
Flush before drinking
If water has sat in pipes more than six hours, run the cold tap for two minutes before drinking or cooking.

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