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Sonora Estates Mobile Home Park

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
235 people
Connections
84
Water source
Groundwater
Based in
Yorba Linda, CA
County
Tuolumne
Owner
Private
Hardness
Very hard
The ZIP code it serves

95370

The short answer

Nothing in EPA’s and California’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.

What was found

Nitrate, chromium (total), fluoride, arsenic and total trihalomethanes (TTHM): California’s own results, samples taken from Nov. 23, 2020 to Oct. 14, 2025, with EPA’s 2012 to 2019 file for earlier years.

Haloacetic acids (HAA5): EPA’s compliance monitoring file, samples taken from Dec. 29, 2014 to Dec. 29, 2014. Newer results are in the utility’s annual water quality report.

Below EPA’s limits3

Nitrate

Comes from the source

Below EPA’s limits

2.7ppm

Highest sample; found in 12 of 12

2025 average: 2.3 ppm

The highest sample, in 2024, was 2.7 ppm, below EPA’s legal limit of 10 ppm. In 2025, the latest year on file, its two samples averaged 2.3 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 3.0 ppm, in 2018.

What handles it

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

Chromium (total)

Comes from the source

Below EPA’s limits

5.8ppb

Highest yearly average, 2022

Averaged by year, the highest was 5.8 ppb, in 2022, below EPA’s legal limit of 100 ppb. Its highest single sample was 11.5 ppb. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 15.5 ppb, in 2013.

What handles it

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.055ppm

Highest yearly average, 2022

Averaged by year, the highest was 0.055 ppm, in 2022, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.11 ppm. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.18 ppm, in 2016.

What handles it

4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Haloacetic acids (HAA5)
  • Lead
  • Total trihalomethanes (TTHM)

Hardness

Very hard, typically 296 mg/L (17.3 grains per gallon), across 2 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 17.3 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

No health-based violations on file with EPA since 2016. There is 1 monitoring or reporting violation: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Nitrate, chromium (total), fluoride, arsenic and total trihalomethanes (TTHM) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Haloacetic acids (HAA5) comes from EPA’s file alone, which ends in 2019. Sonora Estates Mobile Home Park’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. 23, 2020 to Oct. 14, 2025; EPA’s compliance samples are from Dec. 29, 2014 to Dec. 29, 2014.

Testing your own tap

Sonora Estates Mobile Home Park’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 3 labs California certifies closest to the area Sonora Estates Mobile Home Park serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Precision Enviro-Tech

    Twain Harte, CA · about 8 miles

    Certified for bacteria

    (209) 477-8105

  • 49er Water Laboratory

    Jackson, CA · about 34 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (530) 277-2770

  • Aemtek, Inc.

    Modesto, CA · about 41 miles

    Certified for bacteria

    (510) 979-1979

All 145 certified labs for California

Sources

PWSID CA5500086. Rebuilt from EPA data on Oct. 18, 2026.

Also in Tuolumne County

All California utilities

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