South Dakota Water Report Card: Worst Water Systems
The most contaminated public water systems in South Dakota, ranked by PFAS levels, lead, and EPA violations from official EPA data.
Quick Answer
Nps-Mount Rushmore National Memorial has the highest PFAS in South Dakota at 20.8 ppt (5x the EPA limit). Garretson has the highest lead at 34 ppb. The tables below rank the worst systems in each category so you can see how your water compares.
Highest PFAS Levels in South Dakota
Public water systems in South Dakota with the highest peak PFAS ("forever chemical") reading in EPA UCMR5 testing (2023-2025). The EPA enforceable limit for PFOA and PFOS is 4 ppt.
| # | Water System | Location | Peak PFAS (ppt) | Compounds | vs 4 ppt limit |
|---|---|---|---|---|---|
| 1 | Nps-Mount Rushmore National Memorial | – | 20.8 | 2 | 5x |
| 2 | Aberdeen | Aberdeen · 27,989 served | 8.1 | 1 | 2x |
| 3 | Wr/Lj - Mni Wiconi | Murdo · 4,720 served | 8.1 | 1 | 2x |
| 4 | Lincoln County Rural Water System | Sioux Falls · 5,965 served | 6.1 | 1 | 2x |
| 5 | Rapid Valley Sanitary District | Rapid City · 11,408 served | 5.8 | 2 | 1x |
| 6 | Rapid City | Rapid City · 72,009 served | 5.6 | 1 | 1x |
| 7 | Harrisburg, Sd | Harrisburg · 10,297 served | 5.5 | 1 | 1x |
Highest Lead Levels in South Dakota
Community water systems in South Dakota with the highest 90th-percentile lead result under the EPA Lead and Copper Rule. The EPA action level is 15 ppb; there is no safe level of lead for children.
| # | Water System | Location | Lead 90th-pctile (ppb) | vs 15 ppb |
|---|---|---|---|---|
| 1 | Garretson | Garretson · 1,228 served | 34 | 2.3x over |
| 2 | Salem | Salem · 1,325 served | 28 | 1.9x over |
| 3 | Miller | Miller · 1,349 served | 16 | 1.1x over |
| 4 | Brookings Municipal Utilities | Brookings · 23,377 served | 14 | within |
| 5 | Platte | Platte · 1,256 served | 14 | within |
| 6 | Brookings-Deuel Rural Water System | Toronto · 6,200 served | 13 | within |
| 7 | Clear Lake | Clear Lake · 1,218 served | 8 | within |
| 8 | Randall Community Water District | Lake Andes · 6,248 served | 7 | within |
| 9 | Huron | Huron · 14,263 served | 7 | within |
| 10 | Grant-Roberts Rural Water System | Milbank · 5,050 served | 7 | within |
| 11 | Redfield | Redfield · 2,214 served | 6 | within |
| 12 | Hot Springs | Hot Springs · 3,395 served | 6 | within |
Most EPA Violations in South Dakota
Community water systems in South Dakota with the most health-based EPA Safe Drinking Water Act violations on record. A health-based violation means a contaminant exceeded its federal limit or required treatment was not applied.
| # | Water System | Location | Health-based violations |
|---|---|---|---|
| 1 | Box Elder | Box Elder · 14,000 served | 9 |
| 2 | Yankton | Yankton · 15,411 served | 7 |
| 3 | Springfield | Springfield · 2,108 served | 6 |
| 4 | Aberdeen | Aberdeen · 27,989 served | 5 |
| 5 | Wagner | Wagner · 1,490 served | 3 |
| 6 | Eagle Butte | Eagle Butte · 4,000 served | 3 |
| 7 | Parkston | Parkston · 1,567 served | 3 |
| 8 | Fall River Wud | Oral · 1,057 served | 3 |
| 9 | Flandreau | Flandreau · 2,372 served | 3 |
| 10 | Parker | Parker · 1,025 served | 2 |
| 11 | Gregory | Gregory · 1,221 served | 2 |
| 12 | Aurora | Aurora · 1,200 served | 2 |
How This Report Card Is Built
PFAS rankings use EPA UCMR5 monitoring (2023-2025), showing each system's peak detection above the 4 ppt EPA limit. Lead rankings use the EPA Lead and Copper Rule 90th-percentile tap results. Violation counts come from the EPA Safe Drinking Water Information System (SDWIS) and count health-based violations. Lead and violation lists are limited to community water systems serving 1,000 or more people. Figures are the most severe on record and do not necessarily reflect current treated water.
Frequently Asked Questions
What is the most PFAS-contaminated water system in South Dakota?
In EPA UCMR5 testing (2023-2025), Nps-Mount Rushmore National Memorial had the highest recorded PFAS level in South Dakota at 20.8 ppt - about 5x the EPA's 4 ppt limit for PFOA and PFOS.
Which South Dakota water system has the highest lead levels?
Garretson in Garretson had the highest 90th-percentile lead result in South Dakota under the EPA Lead and Copper Rule at 34 ppb - 2.3x the 15 ppb action level.
Which South Dakota water system has the most EPA violations?
Box Elder in Box Elder has the most health-based EPA Safe Drinking Water Act violations on record in South Dakota, with 9 violations.
Where does the South Dakota water report card data come from?
PFAS figures come from EPA UCMR5 monitoring (2023-2025), lead from the EPA Lead and Copper Rule 90th-percentile tap results, and violations from EPA SDWIS health-based violation records. Figures are the most severe on record and do not necessarily reflect current treated water. Check your exact address at knowyourexposure.com.
What South Dakota Residents Should Do
- Look up your exact address at knowyourexposure.com for your system's data
- See the full South Dakota water quality overview
- If your system is listed, a certified filter (reverse osmosis for PFAS, NSF-53 for lead) reduces exposure at the tap. See the best water filters.