Lake Mills Waterworks, WI
Exceeded the action level in the past
Latest 90th-percentile lead: 4.6 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.
About Lake Mills Waterworks
Lake Mills Waterworks serves about 6,211 people through 2,607 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 Jefferson County, Wisconsin. EPA system ID: WI1280108. Ask the utility on your bill for your address in their service line inventory.
Lake Mills Waterworks's lead record
That is down 2.5 ppb from 7.1 ppb in the period ending 2023. The highest 90th-percentile result EPA holds for Lake Mills Waterworks is 18 ppb across 8 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 4.6 ppb |
| 2023 | 7.1 ppb |
| 2023 | 3.9 ppb |
| 2020 | 6.5 ppb |
| 2019 | 7.3 ppb |
| 2018 | 11 ppb over 10 |
| 2018 | 5.7 ppb |
| 2017 | 18 ppb over 15 |
Where this result ranks
Of the 947 Wisconsin systems with a lead result, the median latest reading is 1.33 ppb; 6 are over 15 ppb right now and 71 have gone over at some point. Lake Mills Waterworks's 4.6 ppb sits at the 87th percentile in Wisconsin and the 90th nationally (higher means more lead).
Neighbouring systems
18 other systems share Jefferson County; 3 of them have a higher latest lead result than Lake Mills Waterworks. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Watertown Waterworks | 23,945 | 15 ppb |
| Fort Atkinson Waterworks | 12,390 | 13 ppb |
| Jefferson Waterworks | 7,926 | 3.5 ppb |
| Waterloo Waterworks | 3,520 | 1.3 ppb |
| Johnson Creek Waterworks | 3,318 | 2.8 ppb |
| Palmyra Waterworks | 1,756 | 3.8 ppb |
| Autumn Ridge Water System Llc | 575 | 0.59 ppb |
| Spacious Acres Mobile Home Community | 525 | 0.73 ppb |
| Tremain Mobile Home Park | 475 | 1.46 ppb |
| Lakewood Village | 160 | 2.58 ppb |
What to do in your house
Test your own tap with a certified lab first-draw sample; Lake Mills, WI 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 Lake Mills Waterworks 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. More in what a past exceedance means today.