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Mp Mine Operations LLC

What EPA’s and California’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves
655 people
Connections
9
Water source
Groundwater
Based in
Mountain Pass, CA
County
San Bernardino
Owner
Private
Hardness
Very hard
The ZIP code it serves

92364

The short answer

2 results are above the health goal. The worst: Arsenic, above the health goal. 1 health-based violation since 2016.

What handles it

What was found

Arsenic, uranium, nitrate, fluoride and chromium (total): California’s own results, samples taken from Nov. 18, 2021 to Aug. 29, 2024, with EPA’s 2012 to 2019 file for earlier years.

Total trihalomethanes (TTHM): EPA’s compliance monitoring file, samples taken from Oct. 15, 2019 to Oct. 15, 2019. Newer results are in the utility’s annual water quality report.

Above the health goal2

Arsenic

Comes from the source

Above the health goal

3.8ppb

Highest yearly average, 2021 to 2024

Averaged by year, the highest was 3.8 ppb, in 2024: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 5.0 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.8 ppb, in 2019.

What handles it

  • NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
  • NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”

Uranium

Comes from the source

Above the health goal

5.3ppb

Highest yearly average, 2021 to 2024

2024 average: 5.0 ppb

Averaged by year, the highest was 5.3 ppb, in 2021: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 8.1 ppb. In 2024, the latest year on file, its five samples averaged 5.0 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.3 ppb, in 2018.

What handles it

Below EPA’s limits3

Nitrate

Comes from the source

Below EPA’s limits

6.7ppm

Highest sample; found in 17 of 17

2024 average: 2.8 ppm

The highest sample, in 2021, was 6.7 ppm, below EPA’s legal limit of 10 ppm. In 2024, the latest year on file, its six samples averaged 2.8 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 2.8 ppm, in 2019.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.97ppm

Highest yearly average, 2022

Averaged by year, the highest was 0.97 ppm, in 2022, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 1.3 ppm. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.74 ppm, in 2019.

What handles it

Chromium (total)

Comes from the source

Below EPA’s limits

8.0ppb

Highest yearly average, 2021 to 2024

2024 average: 6.3 ppb

Averaged by year, the highest was 8.0 ppb, in 2021, below EPA’s legal limit of 100 ppb. Its highest single sample was 16 ppb. In 2024, the latest year on file, its four samples averaged 6.3 ppb.

What handles it

2 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Lead
  • Total trihalomethanes (TTHM)

What handles it

A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”

  • NSF/ANSI 53

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: Arsenic

    Other certifiers’ wording: Arsenic (III) (50 ppb influent level)

  • NSF/ANSI 58

    Claims: Arsenic (Pentavalent)<=50 ppb Reduction, Uranium

    For: Arsenic, Uranium

    Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)

At the tap, or for the whole house?

These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. How whole-house systems compare.

Filters with those claims on a certifier’s listing

Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

Compare five-year costs

The best reverse osmosis systems, ranked

Hardness

Very hard, typically 319 mg/L (18.7 grains per gallon), across 4 sampling points, 2019 to 2022.

Hardness is calcium and magnesium. EPA sets no limit for it: it shows up as scale on fixtures and in water heaters, and as soap that won’t lather. USGS calls water above 60 mg/L moderately hard, above 120 hard and above 180 very hard.

Softeners compared at 18.7 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Lead and Copper Rule RevisionsThe required inventory of lead service lines was not completed or submitted on time.EPA: LSL InventoryOct. 17, 2024—Unaddressed
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 1 monitoring or reporting violation not shown.

What this report can’t tell you

  • Everything else. Arsenic, uranium, nitrate, fluoride and chromium (total) results here are California’s own from 2021 on, with EPA’s national file for 2012 to 2019. Total trihalomethanes (TTHM) comes from EPA’s file alone, which ends in 2019. Mp Mine Operations LLC’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.

  • Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.

  • What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.

  • Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; California’s results run from Nov. 18, 2021 to Aug. 29, 2024; EPA’s compliance samples are from Oct. 15, 2019 to Oct. 15, 2019.

Testing your own tap

Mp Mine Operations LLC’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab California certifies.

The 2 labs California certifies closest to the area Mp Mine Operations LLC serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • ASSET Laboratories

    Las Vegas, NV · about 53 miles

    Certified for nitrate, lead and copper, metals, minerals and other inorganics, disinfection byproducts, radioactivity

    (702) 307-2659

  • Western Environmental Testing Laboratory - Las Vegas

    Las Vegas, NV · about 56 miles

    Certified for bacteria, minerals and other inorganics

    (705) 355-0202

All 145 certified labs for California

Sources

PWSID CA3600172. Rebuilt from EPA data on Oct. 18, 2026.

Also in San Bernardino County

All California utilities

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