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Carter Chouteau Co Water Dist

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
150 people
Connections
74
Water source
Surface water
Based in
Carter, MT
County
Chouteau
Owner
Local government
The ZIP code it serves

59442

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, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, nitrate and chromium (total): Montana’s own results, samples taken from Aug. 10, 2020 to Aug. 17, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal2

Arsenic

Comes from the source

Above the health goal

2.1ppb

Highest yearly average, 2020 to 2026

2026 average: 0.045 ppb

Averaged by year, the highest was 2.1 ppb, in 2021: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 48 ppb. In 2026, the latest year on file, its 22 samples averaged 0.045 ppb. EPA recorded no violation for arsenic at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.55 ppb, in 2014.

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

2.0ppb

Highest yearly average, 2021

Averaged by year, the highest was 2.0 ppb, in 2021: below EPA’s legal limit of 30 ppb, but above its health goal of zero. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.0 ppb, in 2014.

What handles it

Below EPA’s limits4

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

44ppb

Highest yearly average, 2020 to 2026

Averaged by year, the highest was 44 ppb, in 2026, below EPA’s legal limit of 80 ppb. Its highest single sample was 47 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 52.5 ppb, in 2017.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

18ppb

Highest yearly average, 2020 to 2026

2026, one sample: 3.9 ppb

Averaged by year, the highest was 18 ppb, in 2020, below EPA’s legal limit of 60 ppb. In 2026, the latest year on file, its one sample was 3.9 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 29 ppb, in 2012.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

1.0ppm

Highest yearly average, 2021

Averaged by year, the highest was 1.0 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. That is the only year on file.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

0.07ppm

Highest sample; found in 6 of 7

2026, one sample: 0.06 ppm

The highest sample, in 2025, was 0.07 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its one sample was 0.06 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.1 ppm, in 2018.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
2 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)
  • Lead

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

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Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Long Term 2 Enhanced Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)Dec. 1, 2025 to Dec. 31, 2025—Archived
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 30 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Arsenic, uranium, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, nitrate and chromium (total) results here are Montana’s own from 2020 on, with EPA’s national file for 2012 to 2019. Carter Chouteau Co Water Dist’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. 10, 2020 to Aug. 17, 2026.

Testing your own tap

Carter Chouteau Co Water Dist’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.

No lab Montana certifies is within 75 miles of the area Carter Chouteau Co Water Dist serves on the state’s list. Some take samples by mail; the state’s page lists them all.

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 MT0000520. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Chouteau County

All Montana utilities

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