Hartley Mutual Water System, CA
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2024-2026). 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
Hartley Mutual Water System serves about 41 people through 15 service connections, which makes it a very small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Butte County, California. EPA system ID: CA0400003; phone on file: 530-575-2760. 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 2017 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Hartley Mutual Water System is 0 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 0 (not detected) |
| 2017 | 0 (not detected) |
| 2017 | 0 (not detected) |
| 2016 | 0 (not detected) |
How Hartley Mutual Water System compares
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. Hartley Mutual Water System's reported as 0 (not detected) sits at the 5th percentile in California and the 2nd nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
41 other systems share Butte County; 14 of them have a higher latest lead result than Hartley Mutual Water System. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Cal-Water Service Co.-Chico | 110,473 | 0 (not detected) |
| South Feather W&P - Miners Ranch | 22,638 | 0 (not detected) |
| Thermalito Water & Sewer Dist | 12,209 | 0 (not detected) |
| Cal-Water Service Co.-Oroville | 11,047 | 0.9 ppb |
| Del Oro Water Co.-Paradise Pines | 10,738 | 0.54 ppb |
| Paradise Irrigation District | 9,114 | 0 (not detected) |
| City Of Gridley | 7,269 | 0 (not detected) |
| City Of Biggs | 2,060 | 6.91 ppb |
| Durham Irrigation District | 1,581 | 0.74 ppb |
| Del Oro Water Co.-Lime Saddle Marina | 954 | 0 (not detected) |
Next steps for Chico, CA
Look up your address in Hartley Mutual Water System'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 Hartley Mutual Water System whether it covers that cost before hiring anyone - many utilities now do. Its latest copper 90th percentile is 1850 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. A zero today does not rule out a jump later - the rules are tightening in 2027.