CA / Mammoth Lakes
CA · Tap water records
Mammoth Lakes tap water, in plain English
Here is what the EPA's own data shows about tap water in Mammoth Lakes. According to EPA SDWIS data retrieved June 2026, Mammoth Lakes is served by 3 active community water systems, together reported to serve about 8,979 people.
As of June 2026, EPA records show 52 violations across the community water system(s) serving Mammoth Lakes, going back to the earliest EPA record. 44 of these are classified by the EPA as health-based (a contaminant recorded above the limit the EPA tracks); the rest are monitoring or reporting violations. Each is listed by system below, with its status.
What the EPA has on record, by system
Mammoth Cwd
8,234 served · surface water · PWSID CA2610001 - Health-based Surface Water Treatment Rule: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in August 2016. The EPA record for these does not include a measured level. All have since returned to compliance, per EPA records.
- Health-based Coliform (TCR): a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in September 1992. The EPA record for these does not include a measured level. All have since returned to compliance, per EPA records.
- Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2023. All have since returned to compliance, per EPA records.
- Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2023. All have since returned to compliance, per EPA records.
Mountain Meadows Mwc
505 served · groundwater · PWSID CA2600620 - Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 1993. All have since returned to compliance, per EPA records.
Pine Creek Village
240 served · groundwater · PWSID CA1400006 - Health-based Combined Uranium: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 40 times between October 2007 and April 2019. The EPA record lists a level of 21 PCI/L; the limit (MCL) is 20 PCI/L. All have since returned to compliance, per EPA records.
- Health-based Gross Alpha Particle Activity: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 2 times in January 2018. The EPA record lists a level of 16 PCI/L; the limit (MCL) is 15 PCI/L. All have since returned to compliance, per EPA records.
- Monitoring Gross Alpha Particle Activity: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in July 2016. All have since returned to compliance, per EPA records.
- Monitoring Combined Uranium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in July 2016. All have since returned to compliance, per EPA records.
- Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 1993. All have since returned to compliance, per EPA records.
What this means
A health-based violation means a contaminant was recorded above the limit the EPA tracks for it. A monitoring or reporting violation means a required test or report was late or missed — not that a contaminant was measured above a limit. “Returned to compliance” means the EPA recorded the issue as resolved.
This page summarizes the EPA's own records and does not assess whether your water is safe to drink. For the most current details, you can verify every record directly with the EPA, and contact your water system with questions.
Source: U.S. EPA Envirofacts SDWIS, retrieved June 2026. Records cover the EPA's full reporting history for these systems. Verify at EPA ECHO.