Cobblestone Subdivision
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
- 90
- Water source
- Groundwater bought from another system
- Based in
- Bozeman, MT
- County
- Gallatin
- Owner
- Private
The ZIP code it serves
The short answer
Nothing in EPA’s and Montana’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
Total trihalomethanes (TTHM) and haloacetic acids (HAA5): Montana’s own results, samples taken from Aug. 11, 2022 to Aug. 28, 2025, with EPA’s 2012 to 2019 file for earlier years.
Below EPA’s limits2
Total trihalomethanes (TTHM)
Forms or is added in treatment
7.5ppb
Highest yearly average, 2022 to 2025
2025, one sample: 1.1 ppb
Averaged by year, the highest was 7.5 ppb, in 2022, below EPA’s legal limit of 80 ppb. In 2025, the latest year on file, its one sample was 1.1 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.4 ppb, in 2019.
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
0.45ppb
Highest yearly average, 2022 to 2025
2025: not found
Averaged by year, the highest was 0.45 ppb, in 2022, below EPA’s legal limit of 60 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 0.36 ppb, in 2019.
What handles it
No certification claim covers this compound yet.
One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Lead
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. Total trihalomethanes (TTHM) and haloacetic acids (HAA5) results here are Montana’s own from 2022 on, with EPA’s national file for 2012 to 2019. Cobblestone Subdivision’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. 11, 2022 to Aug. 28, 2025.
Testing your own tap
The 3 labs Montana certifies closest to the area Cobblestone Subdivision serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Bridger Analytical Laboratory
Bozeman, MT · about 28 miles
Certified for bacteria, minerals and other inorganics
Energy Laboratories, Inc.
Helena, MT · about 63 miles
Certified for bacteria, minerals and other inorganics, organic chemicals
DPHHS State of Montana Environmental Laboratory
Helena, MT · about 64 miles
Certified for bacteria, minerals and other inorganics, organic chemicals
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
- Certified labs: Montana Department of Public Health and Human Services, Water Laboratory Certification Program, certified laboratories, read Oct. 10, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID MT0004572. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Nothing here is above a health goalIn EPA’s and Montana’s records for this utility. They don’t cover everything, which is why the next step matters.Every contaminant TapBuff tracks
- Get the utility’s own reportCobblestone Subdivision must send you a water quality report every year. It covers contaminants this page does not show.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
- Decide if you want a filter at allA filter for taste or chlorine is a preference, not a need. The standards say what each kind can do.NSF/ANSI standards, decoded