Grassland Colony, MT
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2023-2025). 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.
Who runs the water here
Grassland Colony serves about 80 people through 12 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Cascade County, Montana. EPA system ID: MT0004832; phone on file: 406-403-4640. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Lead results over time
Against the period ending 2022 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Grassland Colony is 0 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2019 | 0 (not detected) |
| 2019 | 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. Grassland Colony's reported as 0 (not detected) sits at the 15th 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.
Other water systems in Cascade County
41 other systems share Cascade County; 17 of them have a higher latest lead result than Grassland Colony. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Great Falls City Of | 60,000 | 12 ppb |
| Malmstrom Air Force Base | 8,850 | 0 (not detected) |
| Sun Prairie Village County | 1,800 | 1 ppb |
| Black Eagle Cascade County Water Sewer | 1,233 | 0 (not detected) |
| Prairie Water Company | 1,000 | 0 (not detected) |
| Cascade Town Of | 650 | 2 ppb |
| Belt Town Of | 600 | 0 (not detected) |
| Vaughn Cascade County Water And Sewer | 585 | 0 (not detected) |
| Two Buttes Water Users Assn | 525 | 2 ppb |
| Gore Hill County Water Dist | 500 | 1 ppb |
Next steps for Great Falls, MT
Look up your address in Grassland Colony'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 Grassland Colony 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. The lead result guide covers how utilities pick the homes they sample. Small systems behave differently: why small systems go over more often.