West Prairie Water Co-Op, IL
Exceeded the action level in the past
Latest 90th-percentile lead: reported as 0 (not detected) (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.
Who runs the water here
West Prairie Water Co-Op serves about 2,395 people through 958 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 Mcdonough County, Illinois. EPA system ID: IL1090030; phone on file: 309-863-1021. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
Against the period ending 2025 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for West Prairie Water Co-Op is 29.5 ppb across 5 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2025 | 0 (not detected) |
| 2024 | 29.5 ppb over 15 |
| 2021 | 2.8 ppb |
| 2018 | 0 (not detected) |
How West Prairie Water Co-Op compares
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. West Prairie Water Co-Op's reported as 0 (not detected) sits at the 42nd percentile in Illinois and the 32nd nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
13 other systems share Mcdonough County; 1 of them has a higher latest lead result than West Prairie Water Co-Op. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Macomb | 15,051 | 0 (not detected) |
| Western Illinois University | 8,000 | 0 (not detected) |
| Bushnell | 2,972 | 0 (not detected) |
| Colchester | 1,395 | 0 (not detected) |
| Blandinsville | 569 | 1.3 ppb |
| Good Hope | 536 | 0 (not detected) |
| Industry | 475 | 0 (not detected) |
| New Salem Pwd | 451 | 0 (not detected) |
| Prairie City | 425 | 0 (not detected) |
| Bardolph | 303 | 0 (not detected) |
What to do in your house
Test your own tap with a certified lab first-draw sample; Macomb, 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 West Prairie Water Co-Op 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. Why an old exceedance still matters: over the limit before, under it now.