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Ten Mile and Pleasant Valley WUA

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
750 people
Connections
310
Water source
Groundwater
Based in
Helena, MT
County
Lewis and Clark
Owner
Private
The ZIP code it serves

59602

The short answer

1 result is above EPA’s legal limit, and 2 more are above the health goal. The worst: Copper, above the action level. 1 health-based violation since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 1998 to 2023.

Arsenic, fluoride, nitrate, total trihalomethanes (TTHM), chromium (total) and haloacetic acids (HAA5): Montana’s own results, samples taken from Jan. 7, 2020 to Jan. 6, 2026, with EPA’s 2012 to 2019 file for earlier years.

Uranium: EPA’s compliance monitoring file, samples taken from Oct. 21, 2019 to Oct. 21, 2019. Newer results are in the utility’s annual water quality report.

Above the legal limit1

Copper

Comes from pipes, often your own

Above the action level

2.1ppm

90th percentile, 2021 to 2023

In the latest period, 9 in 10 homes sampled were at or below 2.1 ppm, above EPA’s action level of 1.3 ppm.

What handles it

Above the health goal2

Arsenic

Comes from the source

Above the health goal

4.0ppb

Highest yearly average, 2020 to 2025

2025, one sample: 3.0 ppb

Averaged by year, the highest was 4.0 ppb, in 2020: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2025, the latest year on file, its one sample was 3.0 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 6.0 ppb, in 2013.

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, 2019

Averaged by year, the highest was 2.0 ppb, in 2019: below EPA’s legal limit of 30 ppb, but above its health goal of zero. That is the only year on file.

What handles it

Below EPA’s limits3

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.36ppm

Highest yearly average, 2020 to 2025

2025, one sample: 0.35 ppm

Averaged by year, the highest was 0.36 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. In 2025, the latest year on file, its one sample was 0.35 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.46 ppm, in 2013.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

0.66ppm

Highest sample; found in 7 of 7

2026, one sample: 0.38 ppm

The highest sample, in 2023, was 0.66 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its one sample was 0.38 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 1.1 ppm, in 2018.

What handles it

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

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

1.2ppb

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 1.2 ppb, in 2020, below EPA’s legal limit of 80 ppb. In 2025, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.8 ppb, in 2019.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)
  • Haloacetic acids (HAA5)
  • 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

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

    For: Copper, Arsenic

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

  • NSF/ANSI 58

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

    For: Copper, Arsenic, Uranium

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

At the tap, or for the whole house?

Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. 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

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Lead and Copper RuleA required study or plan for corrosion control was not done on time.EPA: OCCT/SOWT Study/RecommendationApril 1, 2024—Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 28 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Arsenic, fluoride, nitrate, total trihalomethanes (TTHM), chromium (total) and haloacetic acids (HAA5) results here are Montana’s own from 2020 on, with EPA’s national file for 2012 to 2019. Uranium comes from EPA’s file alone, which ends in 2019. Ten Mile and Pleasant Valley WUA’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; Montana’s results run from Jan. 7, 2020 to Jan. 6, 2026; EPA’s compliance samples are from Oct. 21, 2019 to Oct. 21, 2019.

Testing your own tap

Ten Mile and Pleasant Valley WUA’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 Ten Mile and Pleasant Valley WUA serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Energy Laboratories, Inc.

    Helena, MT · about 10 miles

    Certified for bacteria, minerals and other inorganics, organic chemicals

    (406) 442-0711

  • DPHHS State of Montana Environmental Laboratory

    Helena, MT · about 20 miles

    Certified for bacteria, minerals and other inorganics, organic chemicals

    (406) 444-3444

  • Alpine Analytical

    Helena, MT · about 20 miles

    Certified for bacteria, minerals and other inorganics

    (406) 449-6282

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 MT0002005. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Lewis and Clark County

All Montana utilities

What to do next