Hidden Lake Colony
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
- 80 people
- Connections
- 7
- Water source
- Groundwater
- Based in
- Cut Bank, MT
- County
- Glacier
- Owner
- Private
- Hardness
- Soft
The ZIP code it serves
The short answer
1 result is above the health goal. The worst: Arsenic, above the health goal. 2 health-based violations since 2016.
What handles itWhat was found
Arsenic, nitrate, chromium (total), fluoride and total trihalomethanes (TTHM): Montana’s own results, samples taken from March 16, 2020 to June 30, 2026, with EPA’s 2012 to 2019 file for earlier years.
Haloacetic acids (HAA5) and uranium: EPA’s compliance monitoring file, samples taken from Aug. 31, 2015 to Aug. 26, 2019. Newer results are in the utility’s annual water quality report.
Above the health goal1
Arsenic
Comes from the source
1.3ppb
Highest yearly average, 2020 to 2026
2026: not found
Averaged by year, the highest was 1.3 ppb, in 2021: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 5.0 ppb. In 2026, the latest year on file, it wasn’t found in any of its two samples. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 138 ppb, in 2017, and EPA recorded violations in 2012, 2013, 2014 and 2017.
What handles it
- NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
- NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
Below EPA’s limits1
Nitrate
Comes from the source
0.61ppm
Highest sample; found in 9 of 9
2026, one sample: 0.08 ppm
The highest sample, in 2024, was 0.61 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its one sample was 0.08 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 27 ppm, in 2017, and EPA recorded a violation in 2017.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
6 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Chromium (total)
- Fluoride
- Haloacetic acids (HAA5)
- Lead
- Total trihalomethanes (TTHM)
- Uranium
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
Claim: Arsenic (Pentavalent)<=50 ppb Reduction
For: Arsenic
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
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Arsenic
Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Hardness
Soft, 35 mg/L (2 grains per gallon), at its one sampling point, in 2017.
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.
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Arsenic | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2017 to Dec. 31, 2017 | 0.59 MG/L | Resolved |
| Nitrate-Nitrite | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | July 1, 2017 to Sept. 30, 2017 | 26.1 MG/L | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 48 monitoring or reporting violations not shown. | ||||
What this report can’t tell you
Everything else. Arsenic, nitrate, chromium (total), fluoride and total trihalomethanes (TTHM) results here are Montana’s own from 2020 on, with EPA’s national file for 2012 to 2019. Haloacetic acids (HAA5) and uranium come from EPA’s file alone, which ends in 2019. Hidden Lake Colony’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 March 16, 2020 to June 30, 2026; EPA’s compliance samples are from Aug. 31, 2015 to Aug. 26, 2019.
Testing your own tap
No lab Montana certifies is within 75 miles of the area Hidden Lake Colony 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 MontanaSources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- Montana Department of Environmental Quality, Public Water Supply, results from Jan. 2, 2020 to Oct. 6, 2026, read Oct. 18, 2026
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Hardness: Montana Department of Environmental Quality, Public Water Supply, results from Dec. 18, 2017 to Dec. 18, 2017, read Oct. 18, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID MT0003932. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on ArsenicWhat each one does to health, where it comes from, and the certification claim that addresses it.About Arsenic
- Get the utility’s own reportHidden Lake Colony must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs