County Water Quality Report

Douglas County, Colorado

3 public water systems serving 286,215 residents

Data sources: EPA SDWIS EPA ECHO EWG Tap Water Database Utility CCRs ⓘ How did we get these ratings?
County average grade
D
61/100
Utilities rated 3
Population served 286,215

Top water quality concerns in Douglas County

  • Haloacetic acids (HAA9) significantly above health guidelinein 3 of 3 utilities
  • Arsenic significantly above health guidelinein 2 of 3 utilities
  • Radium, combined (-226 and -228) significantly above health guidelinein 2 of 3 utilities
  • Total trihalomethanes (TTHMs) significantly above health guidelinein 1 of 3 utilities
  • PFAS contaminationin 1 of 3 utilities

All utilities in Douglas County

Click any utility for full grade card, contaminant data, and treatment plant contact info.

C
67/100

CASTLE ROCK TOWN OF

CASTLE ROCK · 106,822 residents

Top concern: Arsenic significantly above health guideline

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D
62/100

HIGHLANDS RANCH WSD

HIGHLANDS RANCH · 103,444 residents

Top concern: Haloacetic acids (HAA9) significantly above health guideline

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D
55/100

PARKER WSD

PARKER · 75,949 residents

Top concern: PFAS contamination

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