PlainWater

Clark County, Illinois

SDWIS compliance plate

Sheet IL023 · Clark County 9 sys · 552 viol · #1990/3254

VIOL-SEVERE · HEALTH-LOW · RANK-LOWER · PHOTO-FINISH · PFAS-CLEAN · SRC-GW · SYS-TINY · BOOK-FULL

  • VIOL-SEVERE 88.9% flagged
  • HEALTH-LOW 13.2% health
  • RANK-LOWER #1990/3254
  • PHOTO-FINISH ±0.0 pp
  • PFAS-CLEAN 0.0% detect
  • SRC-GW GW lead 100%
  • SYS-TINY 9 systems
  • BOOK-FULL 7/7 fields

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

According to EPA SDWIS county population served used on /counties, Clark County ranks #1,990 of 3,254 counties by people served, and #64 of 102 counties in Illinois. See methodology · corpus placement.

Clark County standing, lower-flagged corpus third

Flagged-system rate 88.9% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 13.2% is health-based share in the middle third (≤ 24.5%) . UCMR5 detect rate 0.0% is UCMR5 detect rate at or below the tested-pool lower third (≤ 0.0%) . Population served ranks #1,990 of 3,254 · #64 of 102 in Illinois.

Flagged-rate neighbourhood around Clark County

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

0% 20% 40% 60% 80% 100% Sangamon · lowest Knox · near Morgan · near Pulaski · highest 58.8% 88.9% 88.9% 88.9% 88.9% 88.9% 100%

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

Water Systems

System Name Population Violations PFAS
Clark-Edgar RWD 5,801 6 Clean
Marshall 3,947 58 Clean
Casey 3,274 109 Clean
Martinsville 1,200 57 -
Westfield 678 273 -
Union-York Water District 501 44 -
Hydro Spray Car Wash 25 4 -
Walmart Marshall 25 1 -
Ice House Casey 25 0 -

Compare beyond Illinois

Lower-flagged peers for Clark County

Cross-state counties nearest Clark County on flagged-system share (88.9%) and cumulative violation count (552). 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
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.