Ryan Dam Water System, MT
Exceeded the action level in the past
Latest 90th-percentile lead: 1 ppb (monitoring period 2026-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest result is under the action level, but this system has gone over 15 ppb before. Lead comes from pipes, not the source water, so a home with a lead service line can still be exposed. Test your own tap.
About Ryan Dam Water System
Ryan Dam Water System serves about 230 people through 14 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: MT0000046; phone on file: 406-443-8907. They can tell you what your service line is made of and whether they pay to replace it.
Ryan Dam Water System's lead record
Against the period ending 2025 (1 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Ryan Dam Water System is 22 ppb across 8 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 1 ppb |
| 2025 | 1 ppb |
| 2024 | 2 ppb |
| 2023 | 0 (not detected) |
| 2023 | 1 ppb |
| 2022 | 22 ppb over 15 |
| 2019 | 1 ppb |
| 2016 | 1 ppb |
How Ryan Dam Water System compares
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. Ryan Dam Water System's 1 ppb sits at the 56th percentile in Montana and the 52nd nationally (higher means more lead).
Nearby utilities
41 other systems share Cascade County; 8 of them have a higher latest lead result than Ryan Dam Water System. 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 |
Your move
Test your own tap with a certified lab first-draw sample; Helena, MT may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Ryan Dam Water System 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. Why sampled homes are the worst-case ones is in the guide to reading the number. Why an old exceedance still matters: over the limit before, under it now.