Statewide Compliance and Testing

• Overall Compliance: Approximately 645 public water systems operate across South Dakota. Most municipal systems meet federal Safe Drinking Water Act standards for treated drinking water, though the 2024 Integrated Report found 78.1% of evaluated stream miles failing their assigned beneficial uses — a figure that shapes both source water quality and rural well risk.
• PFAS Monitoring Expansion: DANR launched statewide river PFAS testing in 2025 across 30 monitoring sites to establish baseline data. Results are posted publicly on DANR’s website. Separately, South Dakota is opening an in-state PFAS testing laboratory in partnership with South Dakota State University to reduce reliance on out-of-state labs and speed up monitoring capacity.
• Infrastructure Funding: South Dakota received over $42 million through the federal Bipartisan Infrastructure Law for water system upgrades. The 2026 EPA budget proposes a 54% funding cut, which threatens federal pass-through programmes that South Dakota DANR programmes have historically relied upon — adding uncertainty to ongoing improvement work.

Major Water Sources and Challenges

• Big Sioux River System: Primary water source for eastern South Dakota including the Sioux Falls area. Preliminary 2024 testing by East Dakota Water Development District and South Dakota Mines found PFAS compounds at nine of 11 test sites, with concentrations at Falls Park reaching over 80 ppt — more than 20 times the EPA’s 4 ppt MCL for treated drinking water. Full multi-run sampling continued through 2025.
• Missouri River Basin: Serves western South Dakota communities with generally better surface water quality, though drought conditions periodically affect water availability and require conservation measures.
• Rural Water Systems: The South Dakota Association of Rural Water Systems tested 40 rural water systems for PFAS in cooperation with the EPA. WEB Water Development Association, serving north-central South Dakota, continues to win regional best-tasting drinking water recognition.

PFAS Regulatory Landscape in 2026

• PFOA/PFOS MCLs Retained: In May 2025, the EPA confirmed it would keep the 4 ppt MCLs for PFOA and PFOS (finalised April 2024) but announced its intent to extend compliance deadlines from 2029 to 2031. This gives South Dakota utilities more time but also delays protections for residents.
• Other PFAS MCLs Under Review: The EPA announced its intent to rescind the MCLs for PFHxS, PFNA, GenX (HFPO-DA), and the PFBS hazard index mixture — though a January 2026 federal court denied EPA’s request to vacate these rules. The regulatory picture for these compounds remains uncertain. See our water quality resource hub for updates.
• Military Base Cleanup: Ellsworth Air Force Base groundwater was found contaminated at up to 551,000 ppt as of 2016. Cleanup is ongoing, with affected residents near Box Elder previously provided with alternate water supplies. National Guard facility contamination near Custer and Rapid City is also under investigation.

Rural and Agricultural Impact

• Surface Water Pollution: The 2024 Integrated Report identifies total suspended solids from nonpoint (agricultural) sources as the primary driver of stream impairment for fish and aquatic life. E. coli from livestock and wildlife feces is the primary reason streams fail recreational use standards. 89 stream segments are formally listed as impaired and require TMDL development plans.
• Private Well Contamination: A USGS study detected PFAS in three South Dakota private wells, with concentrations ranging from 2,700 to 84,000 ppt. Rural residents relying on private wells, particularly near military or industrial sites, face heightened risk. Consider using a certified water filter if testing reveals contamination.
• Regulatory Oversight Challenges: The proposed 54% EPA budget cut for 2026 and the federal shift toward “cooperative federalism” place greater responsibility on DANR to protect surface and groundwater quality, despite South Dakota historically relying on voluntary agricultural compliance rather than regulatory enforcement.

Sioux Falls PFAS Settlement: A 2025 Landmark

In June 2025, Sioux Falls received a $37.2 million first instalment from its class action settlement with 3M and DuPont — one of the largest PFAS water contamination payouts to any South Dakota municipality. The city had previously shuttered 21 of its 64 groundwater wells after PFAS contamination was discovered near Sioux Falls Regional Airport, where firefighting foam containing PFAS had been used and stored for decades. Settlement funds are designated to “replenish, protect, and secure” the city’s source water. Sioux Falls continues monthly PFAS testing of all raw water samples and reports current treated water levels well within all applicable health limits.

Looking Forward: 2026 and Beyond

South Dakota enters 2026 at a critical juncture for water quality. The state’s new in-state PFAS testing laboratory will improve monitoring capacity, while ongoing Big Sioux River sampling continues to build the evidence base for treatment decisions. However, federal regulatory retreat — extended compliance deadlines, proposed EPA funding cuts, and rescinded MCLs for some PFAS — places significant additional burden on state agencies and local utilities. With 78.1% of evaluated stream miles failing quality standards and agricultural pollution continuing largely unchecked through voluntary measures, meaningful improvement will require stronger state-level enforcement, sustained infrastructure investment, and public engagement. Residents are encouraged to review their utility’s annual Consumer Confidence Report and, if on private wells, arrange independent testing. Use our water quality checker to explore results for your area.