States › Montana › Fergus County

Fergus County, MT Water Quality

Water quality data for 6 public water systems serving Fergus County, Montana — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 6 water systems · 7 cities
✅
Excellent — All Systems Performing Well

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

A

Fergus County Earns a A

Fergus County: 7 communities across 6 water systems. 100.0% have no open violations.

  • Median lead where detected: 1.50 ppb
  • 4 communities with a lead detection, 3 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
1.5 ppb
Median Lead Level
County-wide, 90th percentile
6
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
  • Moore
    Not detected
    No federal limits exceeded on record
    B
  • Grass Range
    1.00 ppb
    No federal limits exceeded on record
    B
  • Roy
    2.00 ppb
    No federal limits exceeded on record
    B
  • Winifred
    1.00 ppb
    1 health-based violation since 2015
    B
  • Lewistown
    Not detected
    4 health-based violations since 2015
    B
⚠ Needs Attention
  • Lewistown
    Not detected
    4 health-based violations since 2015
    B
  • Denton
    4.00 ppb
    76 health-based violations since 2015
    B
  • Lewistown Heights
    Not detected
    4 health-based violations since 2015
    B
  • Winifred
    1.00 ppb
    1 health-based violation since 2015
    B
  • Moore
    Not detected
    No federal limits exceeded on record
    B
County Lead Level — Median 1.5 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 1.5 ppb — 10% of the federal action level
Systems by Lead Level
Under 5 ppb
4
No Data
3

All Cities in Fergus County

Lewistown Not detected B
Denton 4.00 ppb B
Winifred 1.00 ppb B
Moore Not detected B
Lewistown Heights Not detected B
Grass Range 1.00 ppb B
Roy 2.00 ppb B
Showing 7 cities
No active violations Active violations

About Fergus County Drinking Water

Fergus County is served by 6 water systems covering 7 communities. No community here has an open violation on record.

Of the communities reporting lead results, 4 recorded a detection, with a median of 1.50 ppb — 10% of the federal action level. 3 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 no significant deficiencies.

Frequently Asked Questions

Is Fergus County tap water safe to drink?▼
No community in Fergus County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Fergus County?▼
Among communities with a detection the median is 1.50 ppb, 10% of the 15 ppb action level. 3 reported none detected and 0 reported no result.
How many water systems serve Fergus County?▼
6 community water systems serve 7 communities here.
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