PlainWater

Mahaska County, Iowa

SDWIS compliance plate

Sheet IA123 · Mahaska County 4 sys · 390 viol · #1605/3254

VIOL-SEVERE · HEALTH-LOW · RANK-MID · BELOW-PEER · PFAS-CLEAN · SRC-SW · SYS-TINY · BOOK-FULL

  • VIOL-SEVERE 75.0% flagged
  • HEALTH-LOW 10.5% health
  • RANK-MID #1605/3254
  • BELOW-PEER 1.3 pp cleaner
  • PFAS-CLEAN 0.0% detect
  • SRC-SW SW lead 50%
  • SYS-TINY 4 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Polk County (+ 1.3 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Mahaska County ranks #1,605 of 3,254 counties by people served, and #27 of 99 counties in Iowa. See methodology · corpus placement.

Mahaska County standing, lower-flagged corpus third

Flagged-system rate 75.0% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 10.5% 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 #1,605 of 3,254 · #27 of 99 in Iowa.

Flagged-rate neighbourhood around Mahaska County

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

0% 20% 40% 60% 80% 100% Mahaska · this county · lowest Worth · near 75% 76.3% 78.1% 78.6% 80% 100%

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

Water Systems

System Name Population Violations PFAS
Oskaloosa Municipal Water Dept 12,808 251 Clean
Mahaska Rural Water System, Inc. 9,818 27 Clean
Mahaska Rural Water (New Sharon) 1,368 112 -
Oak Creek MHP 165 0 -

Compare beyond Iowa

Lower-flagged peers for Mahaska County

Cross-state counties nearest Mahaska County on flagged-system share (75.0%) and cumulative violation count (390). 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.