States › Montana › Chouteau County

Chouteau County, MT Water Quality

Water quality data for 7 public water systems serving Chouteau County, Montana — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 7 water systems · 8 cities
✅
Excellent — All Systems Performing Well

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

A

Chouteau County Earns a A

Chouteau County: 8 communities across 7 water systems. 100.0% have no open violations.

  • Median lead where detected: 2.00 ppb
  • 7 communities with a lead detection, 1 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
2 ppb
Median Lead Level
County-wide, 90th percentile
7
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
  • Big Sandy
    Not detected
    No federal limits exceeded on record
    B
  • Loma
    1.00 ppb
    No federal limits exceeded on record
    B
  • Rocky Boy West
    1.00 ppb
    1 health-based violation since 2015
    B
  • Boneau
    1.00 ppb
    1 health-based violation since 2015
    B
  • Geraldine
    3.00 ppb
    2 health-based violations since 2015
    B
⚠ Needs Attention
  • Highwood
    5.00 ppb
    Copper above the 1,300 ppb action level
    B
  • Twin Hills Colony
    2.00 ppb
    11 health-based violations since 2015
    B
  • Fort Benton
    2.00 ppb
    Copper above the 1,300 ppb action level
    B
  • Rocky Boy West
    1.00 ppb
    1 health-based violation since 2015
    B
  • Boneau
    1.00 ppb
    1 health-based violation since 2015
    B
County Lead Level — Median 2 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 2 ppb — 13.3% of the federal action level
Systems by Lead Level
Under 5 ppb
6
5 – 10 ppb
1
No Data
1

All Cities in Chouteau County

Fort Benton 2.00 ppb B
Rocky Boy West 1.00 ppb B
Big Sandy Not detected B
Boneau 1.00 ppb B
Geraldine 3.00 ppb B
Highwood 5.00 ppb B
Loma 1.00 ppb B
Twin Hills Colony 2.00 ppb B
Showing 8 cities
No active violations Active violations

About Chouteau County Drinking Water

Chouteau County is served by 7 water systems covering 8 communities. No community here has an open violation on record.

Of the communities reporting lead results, 7 recorded a detection, with a median of 2.00 ppb — 13% of the federal action level. 1 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 Chouteau County tap water safe to drink?▼
No community in Chouteau County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Chouteau County?▼
Among communities with a detection the median is 2.00 ppb, 13% of the 15 ppb action level. 1 reported none detected and 0 reported no result.
How many water systems serve Chouteau County?▼
7 community water systems serve 8 communities here.
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