PlainWater

Big Horn County, Montana

SDWIS compliance plate

Sheet MT003 · Big Horn County 23 sys · 6,556 viol · #2326/3254

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

  • VIOL-SEVERE 95.7% flagged
  • HEALTH-LOW 3.1% health
  • RANK-LOWER #2326/3254
  • PHOTO-FINISH ±0.0 pp
  • PFAS-CLEAN 0.0% detect
  • SRC-GW GW lead 65%
  • SYS-SMALL 23 systems
  • BOOK-FULL 7/7 fields

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

According to EPA SDWIS county population served used on /counties, Big Horn County ranks #2,326 of 3,254 counties by people served, and #19 of 56 counties in Montana. See methodology · corpus placement.

Big Horn County standing, mid-flagged corpus third

Flagged-system rate 95.7% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 3.1% is health-based share at or below the lower third (≤ 10.3%) . UCMR5 detect rate 0.0% is UCMR5 detect rate at or below the tested-pool lower third (≤ 0.0%) . Population served ranks #2,326 of 3,254 · #19 of 56 in Montana.

Flagged-rate neighbourhood around Big Horn County

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

0% 20% 40% 60% 80% 100% Powder River · lowest Granite · near Big Horn · this county Petroleum · highest 66.7% 95.1% 95.2% 95.6% 95.7% 96.3% 100%

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

Water Systems

Compare beyond Montana

Mid-flagged peers for Big Horn County

Cross-state counties nearest Big Horn County on flagged-system share (95.7%) and cumulative violation count (6,556). 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.