Water quality · South Dakota
Water quality in South Dakota
Water quality (EPA SDWIS) data for ZIP codes in South Dakota. Pick a ZIP below to dive into the water quality summary.
Last verified 2026-05-13 · methodology
What lands here
Pages show the CWS serving the address, any health-based violations in the last 3 years, most recent lead and copper sampling result, and a link to the primary SDWIS record.
Source & refresh
EPA SDWIS. Refreshed quarterly (federal mandate). Primary source →
South Dakota top concern
Radon Zone 1, agricultural water, tornadoes
South Dakota is uniformly Zone 1 radon. Agricultural runoff drives EPA SDWIS nitrate compliance pressure in small rural systems. Tornado risk peaks April-June.
See South Dakota state page for the full state-level rollup across all 12 dimensions.
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