States › Iowa › Dubuque County

Dubuque County, IA Water Quality

Water quality data for 16 public water systems serving Dubuque County, Iowa — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 16 water systems · 17 cities
✅
Excellent — All Systems Performing Well

Water quality across the county is outstanding with minimal violations and very low lead levels.

A

Dubuque County Earns a A

Dubuque County: 17 communities across 16 water systems. 100.0% have no open violations.

  • Median lead where detected: 2.80 ppb
  • 10 communities with a lead detection, 7 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 1 with significant inspection deficiencies
  • 100.0% of communities have no open violations
2.8 ppb
Median Lead Level
County-wide, 90th percentile
16
Water Systems
Active CWS & NTNCWS
100%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Asbury
    Not detected
    No federal limits exceeded on record
    A
  • Cascade
    Not detected
    No federal limits exceeded on record
    B
  • Epworth
    3.90 ppb
    No federal limits exceeded on record
    B
  • Peosta
    0.50 ppb
    No federal limits exceeded on record
    B
  • Worthington
    Not detected
    No federal limits exceeded on record
    B
⚠ Needs Attention
  • Centralia
    5.00 ppb
    Copper above the 1,300 ppb action level
    B
  • Dyersville
    1.70 ppb
    7 health-based violations since 2015
    B
  • Farley
    1.30 ppb
    3 health-based violations since 2015
    B
  • New Vienna
    Not detected
    1 significant inspection deficiency
    B
  • Dubuque
    5.00 ppb
    Lead at 5.00 ppb, above a third of the action level
    A
County Lead Level — Median 2.8 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 2.8 ppb — 18.7% of the federal action level
Systems by Lead Level
Under 5 ppb
8
5 – 10 ppb
2
No Data
7

All Cities in Dubuque County

Dubuque 5.00 ppb A
Asbury Not detected A
Dyersville 1.70 ppb B
Cascade Not detected B
Epworth 3.90 ppb B
Farley 1.30 ppb B
Peosta 0.50 ppb B
New Vienna Not detected B
Worthington Not detected B
Holy Cross Not detected B
Luxemburg 0.80 ppb B
Sherrill 4.60 ppb B
Bernard 1.03 ppb B
Centralia 5.00 ppb B
Rickardsville 4.60 ppb B
Sageville Not detected B
Balltown Not detected B
Showing 17 cities
No active violations Active violations

About Dubuque County Drinking Water

Dubuque County is served by 16 water systems covering 17 communities. No community here has an open violation on record.

Of the communities reporting lead results, 10 recorded a detection, with a median of 2.80 ppb — 19% of the federal action level. 7 reported none detected, which means below the laboratory limit rather than an absence of lead.

No community here has PFAS above the federal limit on record. State inspectors recorded significant deficiencies at 1 of them.

Frequently Asked Questions

Is Dubuque County tap water safe to drink?▼
No community in Dubuque County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Dubuque County?▼
Among communities with a detection the median is 2.80 ppb, 19% of the 15 ppb action level. 7 reported none detected and 0 reported no result.
How many water systems serve Dubuque County?▼
16 community water systems serve 17 communities here.
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