Mi Wuk Heights Mwc, CA
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (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. The latest 90th-percentile result was reported as 0 (not detected at the lab's limit). That says the sampled homes were low, not that your home has no lead service line. Check your utility's service line inventory for your address.
About Mi Wuk Heights Mwc
Mi Wuk Heights Mwc serves about 445 people through 159 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Tuolumne County, California. EPA system ID: CA5500060; phone on file: 209-586-2523. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Lead results over time
Against the period ending 2022 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Mi Wuk Heights Mwc is 3.11 ppb across 6 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2019 | 3.11 ppb |
| 2019 | 3.11 ppb |
| 2016 | 0 (not detected) |
Where this result ranks
Of the 2,884 California systems with a lead result, the median latest reading is 0 ppb; 30 are over 15 ppb right now and 215 have gone over at some point. Mi Wuk Heights Mwc's reported as 0 (not detected) sits at the 36th percentile in California and the 21st nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
48 other systems share Tuolumne County; 16 of them have a higher latest lead result than Mi Wuk Heights Mwc. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Tud - Upper Basin Water System | 13,331 | 0 (not detected) |
| Tud - Sonora/Jamestown Water System | 11,113 | 0 (not detected) |
| Tud - Columbia Water System | 5,482 | 5.4 ppb |
| Cdcr - Sierra Conservation Center | 3,571 | 0 (not detected) |
| Groveland Community Serv Dist | 3,400 | 0 (not detected) |
| Twain Harte Community Services District | 2,378 | 0 (not detected) |
| Tud - Tuolumne Water System | 1,798 | 0 (not detected) |
| Tud - Ponderosa | 1,781 | 0 (not detected) |
| Cold Springs Water Co | 1,771 | 2.8 ppb |
| Lake Don Pedro Csd | 1,700 | 0 (not detected) |
What to do in your house
Look up your address in Mi Wuk Heights Mwc's service line inventory. If it says lead, galvanized or unknown, test your tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Mi Wuk Heights Mwc 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. Small systems behave differently: why small systems go over more often.