Shadow Mountain Mhp, CA
Exceeded the action level in the past
Latest 90th-percentile lead: 2.5 ppb (monitoring period 2026-2028). 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
Shadow Mountain Mhp serves about 126 people through 73 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Siskiyou County, California. EPA system ID: CA4700803; phone on file: 949-388-8191. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Every lead result on file
That is down 36.1 ppb from 38.6 ppb in the period ending 2025. The highest 90th-percentile result EPA holds for Shadow Mountain Mhp is 38.6 ppb across 4 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2028 | 2.5 ppb |
| 2025 | 38.6 ppb over 15 |
| 2022 | 1.6 ppb |
| 2019 | 0 (not detected) |
How Shadow Mountain Mhp 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. Shadow Mountain Mhp's 2.5 ppb sits at the 81st percentile in California and the 77th nationally (higher means more lead).
Nearby utilities
29 other systems share Siskiyou County; 6 of them have a higher latest lead result than Shadow Mountain Mhp. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Yreka, City Of | 7,879 | 0.6 ppb |
| Mt. Shasta, City Of | 3,642 | 1.36 ppb |
| Lake Shastina C.S.D | 2,790 | 1.68 ppb |
| Weed, City Of | 2,662 | 0 (not detected) |
| Dunsmuir, City Of | 1,707 | 6.55 ppb |
| Mccloud C.S.D. | 1,317 | 7.4 ppb |
| Montague, City Of | 1,264 | 1.56 ppb |
| Happy Camp C.S.D. | 1,100 | 1.62 ppb |
| Tulelake, City Of | 925 | 1.6 ppb |
| Dorris, City Of | 887 | 0 (not detected) |
Next steps for San Juan Capistrano, CA
Test your own tap with a certified lab first-draw sample; San Juan Capistrano, 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 Shadow Mountain Mhp 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. Why an old exceedance still matters: over the limit before, under it now.