Decorah Water Department, IA
Lead detected, under the action levels
Latest 90th-percentile lead: 9.4 ppb (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. 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.
Who runs the water here
Decorah Water Department serves about 7,615 people through 2,800 service connections, which makes it a medium-sized 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: IA9630012; phone on file: 563-382-5171. They can tell you what your service line is made of and whether they pay to replace it.
Lead results over time
That is up 3.9 ppb from 5.5 ppb in the period ending 2022. The highest 90th-percentile result EPA holds for Decorah Water Department is 10.1 ppb across 4 monitoring periods, none of them over 15 ppb (1 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 9.4 ppb |
| 2022 | 5.5 ppb |
| 2019 | 10.1 ppb over 10 |
| 2016 | 8.3 ppb |
How Decorah Water Department compares
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. Decorah Water Department's 9.4 ppb sits at the 97th percentile in Iowa and the 97th nationally (higher means more lead).
Other water systems in Winneshiek County
12 other systems share Winneshiek County; 0 of them have a higher latest lead result than Decorah Water Department. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Calmar Water Supply | 1,125 | 3.7 ppb |
| Ossian Water Supply | 802 | 5.1 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; Decorah, 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 Decorah Water Department 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. The action level is dropping - the 10 ppb rule from 2027.