Estero Mutual, 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.
Who runs the water here
Estero Mutual serves about 206 people through 148 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws surface water, in Marin County, California. EPA system ID: CA2100519; phone on file: 707-878-2400. 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 2022 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Estero Mutual is 5.5 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2019 | 0 (not detected) |
| 2016 | 5.5 ppb |
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. Estero Mutual's reported as 0 (not detected) sits at the 28th percentile in California and the 15th 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 Marin County; 4 of them have a higher latest lead result than Estero Mutual. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Marin Municipal Water District | 188,116 | 0 (not detected) |
| North Marin Water District | 61,691 | 0 (not detected) |
| Bolinas Community Pud | 1,937 | 0 (not detected) |
| North Marin Wd - Pt. Reyes | 1,841 | 0 (not detected) |
| Inverness Public Utility Dist | 1,445 | 5.3 ppb |
| Lawson S Landing | 946 | 0 (not detected) |
| Stinson Beach County Wtr Dist | 583 | 0 (not detected) |
| Coast Springs - Cal. Water Service (Puc) | 445 | 0 (not detected) |
| Muir Beach Community | 336 | 10 ppb |
| Green Gulch Farm | 75 | 3 ppb |
What to do in your house
Look up your address in Estero Mutual'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 Estero Mutual 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. Small systems behave differently: why small systems go over more often.