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Stone Ridge Water Company

What EPA’s and Montana’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
50 people
Connections
31
Water source
Groundwater
Based in
Polson, MT
County
Lake
Owner
Private
Hardness
Very hard
The ZIP code it serves

59914

The short answer

1 result is above the health goal. The worst: Uranium, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

Uranium, nitrate, fluoride, arsenic, chromium (total) and total trihalomethanes (TTHM): Montana’s own results, samples taken from Aug. 27, 2020 to July 15, 2026.

Above the health goal1

Uranium

Comes from the source

Above the health goal

16.3ppb

Highest yearly average, 2021 to 2023

2023, one sample: 15.4 ppb

Averaged by year, the highest was 16.3 ppb, in 2022: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 17.2 ppb. In 2023, the latest year on file, its one sample was 15.4 ppb.

What handles it

Below EPA’s limits2

Nitrate

Comes from the source

Below EPA’s limits

1.2ppm

Highest sample; found in 4 of 5

2026, one sample: 1.2 ppm

The highest sample, in 2026, was 1.2 ppm, below EPA’s legal limit of 10 ppm. That was also the latest year on file, and its one sample was 1.2 ppm.

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

0.43ppm

Highest yearly average, 2020 to 2026

2026, one sample: 0.38 ppm

Averaged by year, the highest was 0.43 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. In 2026, the latest year on file, its one sample was 0.38 ppm.

What handles it

4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • 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.”

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

None of the filters TapBuff has checked so far carry these claims. Search the certifier listings for the claim above.

Compare five-year costs

Hardness

Very hard, 210 mg/L (12.3 grains per gallon), at its one sampling point, in 2021.

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 12.3 grains per gallon, salt includedSoftener or salt-free conditioner?Montana water hardness, utility by utility

Violations since 2016

No health-based violations on file with EPA since 2016. There are 3 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Uranium, nitrate, fluoride, arsenic, chromium (total) and total trihalomethanes (TTHM) results here are Montana’s own from 2020 on, with EPA’s national file for 2012 to 2019. Stone Ridge Water Company’s own annual report, which it must send you every year, has 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; Montana’s results run from Aug. 27, 2020 to July 15, 2026.

Testing your own tap

Stone Ridge Water Company’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 Montana certifies.

The 3 labs Montana certifies closest to the area Stone Ridge Water Company serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Montana Environmental Laboratory

    Kalispell, MT · about 26 miles

    Certified for bacteria, minerals and other inorganics

    (406) 755-2131

  • Mission Mountain Laboratories

    Ravalli, MT · about 39 miles

    Certified for bacteria

    (406) 370-1089

  • Missoula CCHD Water Lab

    Missoula, MT · about 68 miles

    Certified for bacteria

    (406) 523-4755

Montana State Environmental Laboratory: Private well testing packages for bacteria, metals, nutrients, anions, organic chemicals and more, open to the public. Samples can be mailed, sent by the lab's free courier, or dropped off at the lab. Environmental Laboratory, Montana Department of Public Health and Human Services.

All 36 certified labs for Montana

Sources

PWSID MT0004605. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Lake County

All Montana utilities

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