Corinthian Bay Mutual Water Company, CA
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.
About Corinthian Bay Mutual Water Company
Corinthian Bay Mutual Water Company serves about 75 people through 74 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Lake County, California. EPA system ID: CA1700549; phone on file: 707-489-8981. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Every lead result on file
Against the period ending 2024 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Corinthian Bay Mutual Water Company is 17 ppb across 7 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2024 | 0 (not detected) |
| 2023 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2021 | 17 ppb over 15 |
| 2018 | 0 (not detected) |
Against other California systems
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. Corinthian Bay Mutual Water Company's reported as 0 (not detected) sits at the 14th percentile in California and the 7th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Other water systems in Lake County
41 other systems share Lake County; 10 of them have a higher latest lead result than Corinthian Bay Mutual Water Company. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Highlands Mutual Water Company | 7,772 | 0 (not detected) |
| Hidden Valley Lake Csd | 6,235 | 0 (not detected) |
| Konocti County Water District | 5,928 | 0 (not detected) |
| Lakeport, City Of | 4,762 | 0 (not detected) |
| Golden State Water Co.-Clearlake System | 4,623 | 4.1 ppb |
| Mt. Konocti Mutual Water Company | 4,360 | 0 (not detected) |
| Kelseyville Co Waterworks District 3 | 4,102 | 5.2 ppb |
| Lake County Csa 21 - North Lakeport | 4,046 | 0 (not detected) |
| Cobb Area County Water District | 3,515 | 0 (not detected) |
| Nice Mutual Water Company | 2,929 | 0 (not detected) |
Next steps for Lakeport, CA
Test your own tap with a certified lab first-draw sample; Lakeport, CA 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 Corinthian Bay Mutual Water Company 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. More in what a past exceedance means today.