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Counties → South Dakota

Day County, South Dakota

SDWIS compliance plate

Sheet SD037 · Day County 6 sys · 432 viol · #2994/3254

VIOL-SEVERE · HEALTH-LOW · RANK-BOTTOM · PHOTO-FINISH · PFAS-NONE · SRC-SW · SYS-TINY · BOOK-MOST

  • VIOL-SEVERE 100.0% flagged
  • HEALTH-LOW 6.7% health
  • RANK-BOTTOM #2994/3254
  • PHOTO-FINISH ±0.0 pp
  • PFAS-NONE No UCMR5 set
  • SRC-SW SW lead 67%
  • SYS-TINY 6 systems
  • BOOK-MOST 6/7 fields

Nearest flagged-rate peer: Brown County (+ 0 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Day County ranks #2,994 of 3,254 counties by people served, and #39 of 65 counties in South Dakota. See methodology · corpus placement.

Day County standing, mid-flagged corpus third

Flagged-system rate 100.0% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 6.7% is health-based share at or below the lower third (≤ 10.3%) . No UCMR5 tests in this extract for Day County . Population served ranks #2,994 of 3,254 · #39 of 65 in South Dakota.

Flagged-rate neighbourhood around Day County

Lowest/highest poles plus in-state counties nearest Day County on % of SDWIS systems with ≥1 violation. Full ladder: /counties.

0% 20% 40% 60% 80% 100% Shannon · lowest Buffalo · highest Lincoln · near Codington · near 50% 100% 100% 100% 100% 100% 100%

Source: EPA SDWIS (county aggregates) As of 2026-05-15

Water Systems

System Name Population Violations PFAS
Webster 1,696 14 -
Waubay 473 176 -
Bristol 288 38 -
Roslyn 181 66 -
Pierpont 129 34 -
Grenville 48 104 -

Compare beyond South Dakota

Mid-flagged peers for Day County

Cross-state counties nearest Day County on flagged-system share (100.0%) and cumulative violation count (432). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.