Cobblestone Subdivision, MT
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2022-2024). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest 90th-percentile result was reported as 0 (not detected at the lab's limit). That says the sampled homes were low, not that your home has no lead service line. Check your utility's service line inventory for your address.
About Cobblestone Subdivision
Cobblestone Subdivision serves about 150 people through 90 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Gallatin County, Montana. EPA system ID: MT0004572; phone on file: 406-581-0142. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Cobblestone Subdivision's lead record
Against the period ending 2021 (1 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Cobblestone Subdivision is 1 ppb across 3 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2024 | 0 (not detected) |
| 2021 | 1 ppb |
| 2020 | 0 (not detected) |
Against other Montana systems
Of the 753 Montana systems with a lead result, the median latest reading is 1 ppb; 5 are over 15 ppb right now and 28 have gone over at some point. Cobblestone Subdivision's reported as 0 (not detected) sits at the 25th percentile in Montana and the 13th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Nearby utilities
59 other systems share Gallatin County; 51 of them have a higher latest lead result than Cobblestone Subdivision. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Bozeman City Of | 56,000 | 1.6 ppb |
| Belgrade City Of | 10,460 | 1.79 ppb |
| West Yellowstone Town Of | 9,899 | 1.25 ppb |
| North Star Zoot Water | 4,323 | 3 ppb |
| River Rock County Water And Sewer Dist | 4,200 | 2.81 ppb |
| Rae Water And Sewer Dist 313 | 2,325 | 2.08 ppb |
| Three Forks City Of | 1,900 | 2 ppb |
| Manhattan Town Of | 1,800 | 2 ppb |
| Valley Grove Subdivision | 825 | 2.04 ppb |
| Landmark Subdivision | 750 | 0 (not detected) |
What to do in your house
Look up your address in Cobblestone Subdivision's service line inventory. If it says lead, galvanized or unknown, test your tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Cobblestone Subdivision whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. What a 90th-percentile result does and does not tell you: how to read a lead result. Small systems behave differently: why small systems go over more often.