Mason County, Washington
SDWIS compliance plate
Sheet WA045 · Mason County 241 sys · 10,829 viol · #684/3254
VIOL-SEVERE · HEALTH-LOW · RANK-UPPER · PHOTO-FINISH · PFAS-MID · SRC-GW · SYS-LARGE · BOOK-FULL
- VIOL-SEVERE 97.1% flagged
- HEALTH-LOW 7.2% health
- RANK-UPPER #684/3254
- PHOTO-FINISH ±0.3 pp
- PFAS-MID 25.0% detect
- SRC-GW GW lead 100%
- SYS-LARGE 241 systems
- BOOK-FULL 7/7 fields
Nearest flagged-rate peer: King County ( -0.3 pp flagged-rate)
According to EPA SDWIS county population served used on /counties, Mason County ranks #684 of 3,254 counties by people served, and #20 of 39 counties in Washington. See methodology · corpus placement.
Mason County standing, mid-flagged corpus third
Flagged-system rate 97.1% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 7.2% is health-based share at or below the lower third (≤ 10.3%) . UCMR5 detect rate 25.0% is UCMR5 detect rate in the tested-pool middle third (≤ 33.3%) . Population served ranks #684 of 3,254 · #20 of 39 in Washington.
Flagged-rate neighbourhood around Mason County
Lowest/highest poles plus in-state counties nearest Mason County on % of SDWIS systems with ≥1 violation. Full ladder: /counties.
Water Systems
Compare beyond Washington
Mid-flagged peers for Mason County
Cross-state counties nearest Mason County on flagged-system share (97.1%) and cumulative violation count (10,829). 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.
Similar violation load
Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).
Read our methodology · Check your water system - how this data is sourced, computed, and verified.
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.