Golden State Water Company - Los Osos, CA
Lead detected, under the action levels
Latest 90th-percentile lead: 2.8 ppb (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. 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.
Golden State Water Company - Los Osos at a glance
Golden State Water Company - Los Osos serves about 5,942 people through 2,690 service connections, which makes it a medium-sized system under EPA's size classes. It is privately owned and draws groundwater, in San Luis Obispo County, California. EPA system ID: CA4010017; phone on file: 909-730-1161. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Every lead result on file
That is up 2.8 ppb from 0 ppb in the period ending 2023. The highest 90th-percentile result EPA holds for Golden State Water Company - Los Osos is 4.6 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 2.8 ppb |
| 2023 | 0 (not detected) |
| 2020 | 4.6 ppb |
| 2017 | 0 (not detected) |
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. Golden State Water Company - Los Osos's 2.8 ppb sits at the 84th percentile in California and the 80th nationally (higher means more lead).
Neighbouring systems
71 other systems share San Luis Obispo County; 12 of them have a higher latest lead result than Golden State Water Company - Los Osos. 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) |
Next steps for Santa Maria, CA
Test your own tap with a certified lab first-draw sample; Santa Maria, 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 Golden State Water Company - Los Osos 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. Systems that went over once often dip back under; here is what that means.