States › Wisconsin › Grant County

Grant County, WI Water Quality

Water quality data for 22 public water systems serving Grant County, Wisconsin — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 22 water systems · 40 cities
✅
Excellent — All Systems Performing Well

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

A

Grant County Earns a A

Grant County: 40 communities across 22 water systems. 100.0% have no open violations.

  • Median lead where detected: 1.80 ppb
  • 30 communities with a lead detection, 10 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 4 with significant inspection deficiencies
  • 100.0% of communities have no open violations
1.8 ppb
Median Lead Level
County-wide, 90th percentile
22
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
  • Patch Grove
    Not detected
    No federal limits exceeded on record
    B
  • Bloomington
    1.21 ppb
    No federal limits exceeded on record
    A
  • Clifton
    0.88 ppb
    No federal limits exceeded on record
    B
  • Mount Ida
    1.61 ppb
    No federal limits exceeded on record
    B
  • Woodman
    2.05 ppb
    No federal limits exceeded on record
    B
⚠ Needs Attention
  • Cassville
    15.10 ppb
    Lead above the 15 ppb action level
    C
  • Cassville
    15.10 ppb
    Lead above the 15 ppb action level
    C
  • Smelser
    Not detected
    Copper above the 1,300 ppb action level
    C
  • Cuba City
    Not detected
    Copper above the 1,300 ppb action level
    C
  • Wyalusing
    3.80 ppb
    1 significant inspection deficiency
    B
County Lead Level — Median 1.8 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 1.8 ppb — 12% of the federal action level
Systems by Lead Level
Under 5 ppb
26
10 – 15 ppb
4
No Data
10

All Cities in Grant County

Platteville 10.30 ppb A
Lancaster 1.80 ppb B
Fennimore 1.61 ppb B
Boscobel 1.10 ppb B
Cuba City Not detected C
Muscoda 2.64 ppb B
Hazel Green 2.83 ppb B
Dickeyville Not detected B
Montfort 1.10 ppb B
Bloomington 1.21 ppb A
Livingston 0.88 ppb B
Cassville 15.10 ppb C
Jamestown Not detected B
Blue River Not detected B
Bagley 3.80 ppb B
Tennyson 3.77 ppb B
Potosi 3.77 ppb B
Marion 2.05 ppb B
Patch Grove Not detected B
Mount Hope 1.50 ppb B
Boscobel 1.10 ppb B
Hazel Green Not detected B
Muscoda 2.64 ppb B
Liberty Not detected B
South Lancaster 1.80 ppb B
Platteville 10.30 ppb A
North Lancaster 1.80 ppb B
Fennimore 1.61 ppb B
Paris Not detected B
Cassville 15.10 ppb C
Mount Ida 1.61 ppb B
Bloomington 1.21 ppb A
Mount Hope 1.50 ppb B
Potosi 1.72 ppb B
Smelser Not detected C
Clifton 0.88 ppb B
Wingville 1.10 ppb B
Woodman 2.05 ppb B
Patch Grove Not detected B
Wyalusing 3.80 ppb B
Showing 40 cities
No active violations Active violations

About Grant County Drinking Water

Grant County is served by 22 water systems covering 40 communities. No community here has an open violation on record.

Of the communities reporting lead results, 30 recorded a detection, with a median of 1.80 ppb — 12% of the federal action level. 10 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 4 of them.

Frequently Asked Questions

Is Grant County tap water safe to drink?▼
No community in Grant County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Grant County?▼
Among communities with a detection the median is 1.80 ppb, 12% of the 15 ppb action level. 10 reported none detected and 0 reported no result.
How many water systems serve Grant County?▼
22 community water systems serve 40 communities here.
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