Ossian Water Supply, IA
Exceeded the action level in the past
Latest 90th-percentile lead: 5.1 ppb (monitoring period 2025-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest 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.
Ossian Water Supply at a glance
Ossian Water Supply serves about 802 people through 430 service connections, which makes it a small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Winneshiek County, Iowa. EPA system ID: IA9677007. Ask the utility on your bill for your address in their service line inventory.
Lead results over time
That is down 4 ppb from 9.1 ppb in the period ending 2024. The highest 90th-percentile result EPA holds for Ossian Water Supply is 22.7 ppb across 6 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 5.1 ppb |
| 2024 | 9.1 ppb |
| 2024 | 8.7 ppb |
| 2023 | 22.7 ppb over 15 |
| 2020 | 8.9 ppb |
| 2017 | 8.8 ppb |
Against other Iowa systems
Of the 1,066 Iowa systems with a lead result, the median latest reading is 1.4 ppb; 4 are over 15 ppb right now and 36 have gone over at some point. Ossian Water Supply's 5.1 ppb sits at the 89th percentile in Iowa and the 91st nationally (higher means more lead).
Nearby utilities
12 other systems share Winneshiek County; 4 of them have a higher latest lead result than Ossian Water Supply. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Decorah Water Department | 7,615 | 9.4 ppb |
| Calmar Water Supply | 1,125 | 3.7 ppb |
| Freeport Water District | 775 | 1.8 ppb |
| Spillville Water Supply | 371 | 5.8 ppb |
| Fort Atkinson Water Works | 347 | 2.5 ppb |
| Ridgeway, City Of | 275 | 4.8 ppb |
| Castalia Water Works | 145 | 0.6 ppb |
| Frankville Rwd | 135 | 2 ppb |
| Scenic View Estates | 78 | 0.8 ppb |
| Sherman Place Water & Road, Inc. | 73 | 4 ppb |
What to do in your house
Test your own tap with a certified lab first-draw sample; Ossian, IA 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 Ossian Water Supply 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. More in what a past exceedance means today.