Mount Carroll, IL
Lead detected, under the action levels
Latest 90th-percentile lead: 1.1 ppb (monitoring period 2022-2024). 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 Mount Carroll
Mount Carroll serves about 1,479 people through 855 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 Carroll County, Illinois. EPA system ID: IL0150200; phone on file: 815-244-4424. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Every lead result on file
Against the period ending 2021 (1.2 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Mount Carroll is 1.2 ppb across 3 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2024 | 1.1 ppb |
| 2021 | 1.2 ppb |
| 2018 | 0 (not detected) |
Against other Illinois systems
Of the 1,744 Illinois systems with a lead result, the median latest reading is 0 ppb; 22 are over 15 ppb right now and 152 have gone over at some point. Mount Carroll's 1.1 ppb sits at the 61st percentile in Illinois and the 57th nationally (higher means more lead).
Other water systems in Carroll County
9 other systems share Carroll County; 4 of them have a higher latest lead result than Mount Carroll. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Savanna | 3,020 | 0 (not detected) |
| Thomson Maximum Security Center | 2,166 | - |
| Lanark | 1,504 | 5.1 ppb |
| Milledgeville | 989 | 5.45 ppb |
| Shannon | 801 | 0 (not detected) |
| Thomson | 600 | 0.59 ppb |
| Chadwick | 523 | 5.33 ppb |
| Mountain Vale Village Mhp | 388 | - |
| Carroll Heights Utilities Company | 80 | 3 ppb |
What to do in your house
Test your own tap with a certified lab first-draw sample; Mt Carroll, IL 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 Mount Carroll 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. The lead result guide covers how utilities pick the homes they sample. The action level is dropping - the 10 ppb rule from 2027.