Black Rock Estates Subdivision, MT
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2025-2027). 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.
Black Rock Estates Subdivision at a glance
Black Rock Estates Subdivision serves about 75 people through 57 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Yellowstone County, Montana. EPA system ID: MT0004881; phone on file: 406-652-5523. They can tell you what your service line is made of and whether they pay to replace it.
Every lead result on file
That is down 2 ppb from 2 ppb in the period ending 2024. The highest 90th-percentile result EPA holds for Black Rock Estates Subdivision is 8 ppb across 6 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2027 | 0 (not detected) |
| 2024 | 2 ppb |
| 2023 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2020 | 8 ppb |
| 2019 | 1 ppb |
Where this result ranks
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. Black Rock Estates Subdivision's reported as 0 (not detected) sits at the 13th percentile in Montana and the 7th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
45 other systems share Yellowstone County; 21 of them have a higher latest lead result than Black Rock Estates Subdivision. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Billings City Of | 114,000 | 3 ppb |
| Billings Heights Co Water Dist Of | 12,000 | 3 ppb |
| Laurel Municipal Water System | 6,339 | 2 ppb |
| Lockwood Water And Sewer District | 5,900 | 3 ppb |
| Pioneer Water Service | 900 | 0 (not detected) |
| Go 2 U Water Delivery | 875 | 0 (not detected) |
| Worden Ballantine Yellowstone | 800 | 3 ppb |
| Fisher Water Service | 750 | 0 (not detected) |
| Cherry Creek Estates Llc | 600 | 0 (not detected) |
| Windsor Estates | 530 | 1 ppb |
Your move
Look up your address in Black Rock Estates 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 Black Rock Estates 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. A zero today does not rule out a jump later - the rules are tightening in 2027.