Norris Canyon Property Owners Assn, 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.
Who runs the water here
Norris Canyon Property Owners Assn serves about 50 people through 19 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Alameda County, California. EPA system ID: CA0103040; phone on file: 510-773-6448. 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 Norris Canyon Property Owners Assn is 58.5 ppb across 12 monitoring periods, 2 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2024 | 0 (not detected) |
| 2023 | 3.2 ppb |
| 2022 | 3.1 ppb |
| 2021 | 0 (not detected) |
| 2020 | 4.5 ppb |
| 2019 | 5 ppb |
| 2018 | 17 ppb over 15 |
| 2018 | 58.5 ppb over 15 |
| 2017 | 3.9 ppb |
| 2017 | 0 (not detected) |
| 2016 | 4 ppb |
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. Norris Canyon Property Owners Assn's reported as 0 (not detected) sits at the 7th percentile in California and the 3rd nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Nearby utilities
13 other systems share Alameda County; 3 of them have a higher latest lead result than Norris Canyon Property Owners Assn. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| East Bay Mud | 1,468,000 | 0 (not detected) |
| Alameda County Water District | 344,000 | 0 (not detected) |
| City Of Hayward | 162,954 | 0 (not detected) |
| Dublin San Ramon Services District | 98,776 | 0 (not detected) |
| City Of Pleasanton | 76,689 | 0 (not detected) |
| California Water Service - Livermore | 60,414 | 7.5 ppb |
| City Of Livermore | 38,892 | 0 (not detected) |
| Alameda Point | 600 | 0 (not detected) |
| Castlewood Domestic Water System | 524 | 0 (not detected) |
| Trailer Haven Mobile Home Park | 459 | 2.7 ppb |
Next steps for Castro Valley, CA
Test your own tap with a certified lab first-draw sample; Castro Valley, 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 Norris Canyon Property Owners Assn whether it covers that cost before hiring anyone - many utilities now do. Its latest copper 90th percentile is 2250 ppb (copper action level 1,300 ppb).
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. More in what a past exceedance means today.