MAMMOTH CWD

MAMMOTH LAKES, CA · ~8,234 people served

Check your exact address → MAMMOTH LAKES overview

100

Excellent

PurityRadar safety score

PWSID

CA2610001

State

California

City

MAMMOTH LAKES

Population served

8,234

Primary source

Surface water

Score history

No change since tracking began Jun 18, 2026.

Jun 18, 2026 · score 100 Jun 18, 2026 · score 100

2 score updates logged since tracking began Jun 18, 2026. Each future EPA re-score adds a point.

PFAS & contaminant readings

Latest detections from EPA’s UCMR5 monitoring (through Aug 2025). Levels in parts per trillion (ppt).

Lithium

96,700 ppt

limit —

No federal limit

Violations & enforcement

Violations on record

Unaddressed

Health-based

Enforcement actions

From EPA ECHO (SDWIS), most recent enforcement Jul 2024. Official EPA record →

Monitoring & reporting · Haloacetic acids (HAA5) began Jan 2023 Resolved

Monitoring & reporting · Total trihalomethanes (TTHM) began Jan 2023 Resolved

Treatment technique · EPA contaminant 0200 health-based began Aug 2016 Resolved

Max contaminant level (MCL) · Total coliform health-based began Sep 1992 Resolved

Treatment technique · EPA contaminant 0200 health-based began Jun 1991 Resolved

Recent enforcement actions

State action · SFL Jul 2024
State action · SOX Jul 2024
State action · SOX Apr 2018
State action · SFL Oct 2016
State action · SOX Aug 2016
EPA/federal action · EOX Mar 2000
State action · SOX Jan 1995
EPA/federal action · EOX Dec 1993

Area water-quality monitoring

Environmental monitoring (rivers, wells, intakes) recorded in this system’s service area in the EPA/USGS Water Quality Portal since 2018 — source/ambient water, not finished tap water. Context for the watershed, not a reading from your tap.

ContaminantMedian · max · samples

Nitrate

12 stations · latest Oct 2022

0.096 · max 0.292 mg/l as N · 124

Arsenic

17 stations · latest Nov 2022

97 · max 910 ug/l · 121

Fluoride

17 stations · latest Nov 2022

0.53 · max 12.3 mg/l · 121

Manganese

17 stations · latest Nov 2022

54 · max 767 ug/l · 120

Source: Water Quality Portal (EPA/USGS/state agencies). Values are as-reported and aren’t health thresholds.

This profile is built from EPA public records for system CA2610001 — SDWIS violations and UCMR5 PFAS sampling. The score is system-level and can’t account for your home’s plumbing (older pipes can add lead at the tap). For health decisions, check your exact address, read the utility’s Consumer Confidence Report, and confirm with your provider.