PlainWater

Granite County, Montana

SDWIS compliance plate

Sheet MT039 · Granite County 21 sys · 2,193 viol · #2523/3254

VIOL-SEVERE · HEALTH-LOW · RANK-LOWER · PHOTO-FINISH · PFAS-NONE · SRC-GW · SYS-SMALL · BOOK-MOST

  • VIOL-SEVERE 95.2% flagged
  • HEALTH-LOW 13.8% health
  • RANK-LOWER #2523/3254
  • PHOTO-FINISH ±0.2 pp
  • PFAS-NONE No UCMR5 set
  • SRC-GW GW lead 95%
  • SYS-SMALL 21 systems
  • BOOK-MOST 6/7 fields

Nearest flagged-rate peer: Missoula County ( -0.2 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Granite County ranks #2,523 of 3,254 counties by people served, and #27 of 56 counties in Montana. See methodology · corpus placement.

Granite County standing, mid-flagged corpus third

Flagged-system rate 95.2% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 13.8% is health-based share in the middle third (≤ 24.5%) . No UCMR5 tests in this extract for Granite County . Population served ranks #2,523 of 3,254 · #27 of 56 in Montana.

Flagged-rate neighbourhood around Granite County

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

0% 20% 40% 60% 80% 100% Powder River · lowest Broadwater · near Granite · this county Petroleum · highest 66.7% 95% 95% 95.1% 95.2% 95.6% 100%

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

Water Systems

Compare beyond Montana

Mid-flagged peers for Granite County

Cross-state counties nearest Granite County on flagged-system share (95.2%) and cumulative violation count (2,193). 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.