Riverdale Subdivision, ND
Lead detected, under the action levels
Latest 90th-percentile lead: 7 ppb (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. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
About Riverdale Subdivision
Riverdale Subdivision serves about 88 people through 22 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Cass County, North Dakota. EPA system ID: ND0901365. Ask the utility on your bill for your address in their service line inventory.
Every lead result on file
Against the period ending 2025 (7 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Riverdale Subdivision is 7 ppb across 7 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2027 | 7 ppb |
| 2025 | 7 ppb |
| 2024 | 1.47 ppb |
| 2022 | 1.47 ppb |
| 2021 | 0 (not detected) |
| 2019 | 0 (not detected) |
| 2016 | 4.47 ppb |
Where this result ranks
Of the 300 North Dakota systems with a lead result, the median latest reading is 0.91 ppb; 3 are over 15 ppb right now and 20 have gone over at some point. Riverdale Subdivision's 7 ppb sits at the 94th percentile in North Dakota and the 95th nationally (higher means more lead).
Neighbouring systems
25 other systems share Cass County; 3 of them have a higher latest lead result than Riverdale Subdivision. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Fargo City Of | 120,762 | 1.89 ppb |
| West Fargo City Of | 34,858 | 0 (not detected) |
| Cass Rural Water District Fargo | 4,242 | 1.63 ppb |
| Cass Rural Water District-Phase I | 3,658 | 0 (not detected) |
| Casselton City Of | 2,513 | 12.1 ppb |
| Cass Rural Water District-Phase Ii | 1,700 | 0 (not detected) |
| Cass Rural Water District-Phase Iii | 1,682 | 0 (not detected) |
| Horace City Of | 1,641 | 0 (not detected) |
| Mapleton City Of | 1,320 | 0 (not detected) |
| Harwood City Of | 718 | 6.72 ppb |
Next steps for Horace, ND
Test your own tap with a certified lab first-draw sample; Horace, ND 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 Riverdale Subdivision whether it covers that cost before hiring anyone - many utilities now do. Its latest copper 90th percentile is 2376 ppb (copper action level 1,300 ppb).
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. The action level is dropping - the 10 ppb rule from 2027.