Atascadero State Hospital, CA
Lead detected, under the action levels
Latest 90th-percentile lead: 4.7 ppb (monitoring period 2026-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Who runs the water here
Atascadero State Hospital serves about 1,100 people through 866 service connections, which makes it a small system under EPA's size classes. It is owned by the state and draws groundwater, in San Luis Obispo County, California. EPA system ID: CA4010832; phone on file: 805-468-2249. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
Against the period ending 2025 (4.5 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Atascadero State Hospital is 7 ppb across 6 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 4.7 ppb |
| 2025 | 4.5 ppb |
| 2025 | 6.1 ppb |
| 2024 | 7 ppb |
| 2021 | 0 (not detected) |
| 2018 | 2.2 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. Atascadero State Hospital's 4.7 ppb sits at the 91st percentile in California and the 90th nationally (higher means more lead).
Other water systems in San Luis Obispo County
71 other systems share San Luis Obispo County; 8 of them have a higher latest lead result than Atascadero State Hospital. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| San Luis Obispo Water Department | 49,534 | 0 (not detected) |
| Atascadero Mutual Water Co | 33,307 | 0 (not detected) |
| City Of Paso Robles Water Division | 31,176 | 0 (not detected) |
| City Of Arroyo Grande Utilities Division | 17,963 | 0 (not detected) |
| California Mens Colony | 15,000 | 0 (not detected) |
| Nipomo Comm Services Dist | 13,771 | 0 (not detected) |
| City Of Grover Beach Public Works Dept | 12,701 | 0 (not detected) |
| Morro Bay Pw Dept - Water Division | 10,757 | 0 (not detected) |
| Templeton Csd | 8,041 | 0 (not detected) |
| Pismo Beach Water Department | 7,944 | 0 (not detected) |
What to do in your house
Test your own tap with a certified lab first-draw sample; Atascadero, 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 Atascadero State Hospital whether it covers that cost before hiring anyone - many utilities now do. Its latest copper 90th percentile is 1580 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. Why sampled homes are the worst-case ones is in the guide to reading the number. Size matters more than most people expect: small vs large water systems.