Hermosa-Old System, SD
Lead detected, under the action levels
Latest 90th-percentile lead: 7 ppb (monitoring period 2023-2023). 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
Hermosa-Old System serves about 420 people through 277 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 Custer County, South Dakota. EPA system ID: SD4600154; phone on file: 6052554291. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Hermosa-Old System's lead record
That is up 5 ppb from 2 ppb in the period ending 2020. The highest 90th-percentile result EPA holds for Hermosa-Old System is 7 ppb across 3 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2023 | 7 ppb |
| 2020 | 2 ppb |
| 2017 | 1 ppb |
Against other South Dakota systems
Of the 458 South Dakota systems with a lead result, the median latest reading is 2 ppb; 0 are over 15 ppb right now and 6 have gone over at some point. Hermosa-Old System's 7 ppb sits at the 96th percentile in South Dakota and the 95th nationally (higher means more lead).
Neighbouring systems
9 other systems share Custer County; 0 of them have a higher latest lead result than Hermosa-Old System. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Custer | 1,919 | 2 ppb |
| Spring Creek Acres | 172 | 1 ppb |
| Buffalo Gap | 126 | 2 ppb |
| Hermosa Water Users Association | 108 | 2 ppb |
| Heartland Country Ranchettes | 95 | 1 ppb |
| Rock Ridge Court | 74 | 3 ppb |
| Fairburn Water Association | 65 | 3 ppb |
| North Hermosa Wud | 40 | 1 ppb |
| Paramount Point | 40 | 1 ppb |
Your move
Test your own tap with a certified lab first-draw sample; Hill City, SD 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 Hermosa-Old System 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. Why sampled homes are the worst-case ones is in the guide to reading the number. The action level is dropping - the 10 ppb rule from 2027.