Montana County Water Quality Reports

Beaverhead County, MT: 14 Violations — 54/100 (2026)

2026 report: Beaverhead County, MT scores 54/100 (Grade D). 6 ZIP codes analyzed. 14 EPA violations found. Free report with contaminant data and filter ...

Big Horn County, MT: 10 Health Violations — 45/100 (2026)

2026 report: Big Horn County, MT scores 45/100 (Grade D). 7 ZIP codes analyzed. 59 EPA violations found. Free report with contaminant data and filter pi...

Blaine County, MT: 34 Health Violations — 41/100 (2026)

2026 report: Blaine County, MT scores 41/100 (Grade D). 5 ZIP codes analyzed. 50 EPA violations found. Free report with contaminant data and filter picks.

Broadwater County, MT: 2 Violations — 51/100 (2026)

2026 report: Broadwater County, MT scores 51/100 (Grade D). 4 ZIP codes analyzed. 2 EPA violations found. Free report with contaminant data and filter p...

Carbon County, MT: 2 Health Violations — 58/100 (2026)

2026 report: Carbon County, MT scores 58/100 (Grade C). 11 ZIP codes analyzed. 25 EPA violations found. Free report with contaminant data and filter picks.

Carter County, MT: 9 Violations — 46/100 (2026)

2026 report: Carter County, MT scores 46/100 (Grade D). 4 ZIP codes analyzed. 9 EPA violations found. Free report with contaminant data and filter picks.

Cascade County, MT: 13 Health Violations — 59/100 (2026)

2026 report: Cascade County, MT scores 59/100 (Grade C). 19 ZIP codes analyzed. 93 EPA violations found. Free report with contaminant data and filter pi...

Chouteau County, MT: 2 Health Violations — 59/100 (2026)

2026 report: Chouteau County, MT scores 59/100 (Grade C). 7 ZIP codes analyzed. 40 EPA violations found. Free report with contaminant data and filter pi...

Custer County, MT: 3 Health Violations — 45/100 (2026)

2026 report: Custer County, MT scores 45/100 (Grade D). 5 ZIP codes analyzed. 15 EPA violations found. Free report with contaminant data and filter picks.

Daniels County, MT: 12 Violations — 45/100 (2026)

2026 report: Daniels County, MT scores 45/100 (Grade D). 5 ZIP codes analyzed. 12 EPA violations found. Free report with contaminant data and filter picks.

Dawson County, MT: 9 Violations — 47/100 (2026)

2026 report: Dawson County, MT scores 47/100 (Grade D). 7 ZIP codes analyzed. 9 EPA violations found. Free report with contaminant data and filter picks.

Deer Lodge County, MT: 17 Violations — 57/100 (2026)

2026 report: Deer Lodge County, MT scores 57/100 (Grade C). 2 ZIP codes analyzed. 17 EPA violations found. Free report with contaminant data and filter ...

Fallon County, MT: 12 Violations — 52/100 (2026)

2026 report: Fallon County, MT scores 52/100 (Grade D). 4 ZIP codes analyzed. 12 EPA violations found. Free report with contaminant data and filter picks.

Fergus County, MT: 78 Health Violations — 49/100 (2026)

2026 report: Fergus County, MT scores 49/100 (Grade D). 11 ZIP codes analyzed. 101 EPA violations found. Free report with contaminant data and filter pi...

Flathead County, MT: 27 Violations — 57/100 (2026)

2026 report: Flathead County, MT scores 57/100 (Grade C). 18 ZIP codes analyzed. 27 EPA violations found. Free report with contaminant data and filter p...

Gallatin County, MT: 59 Violations — 62/100 (2026)

2026 report: Gallatin County, MT scores 62/100 (Grade C). 15 ZIP codes analyzed. 59 EPA violations found. Free report with contaminant data and filter p...

Garfield County, MT: 23 Violations — 44/100 (2026)

2026 report: Garfield County, MT scores 44/100 (Grade D). 4 ZIP codes analyzed. 23 EPA violations found. Free report with contaminant data and filter pi...

Glacier County, MT: 7 Violations — 55/100 (2026)

2026 report: Glacier County, MT scores 55/100 (Grade C). 4 ZIP codes analyzed. 7 EPA violations found. Free report with contaminant data and filter picks.

Golden Valley County, MT: 2 Health Violations — 67/100

2026 report: Golden Valley County, MT scores 67/100 (Grade C). 2 ZIP codes analyzed. 7 EPA violations found. Free report with contaminant data and filte...

Granite County, MT: 15 Health Violations — 42/100 (2026)

2026 report: Granite County, MT scores 42/100 (Grade D). 3 ZIP codes analyzed. 15 EPA violations found. Free report with contaminant data and filter picks.

Hill County, MT: 9 Health Violations — 51/100 (2026)

2026 report: Hill County, MT scores 51/100 (Grade D). 7 ZIP codes analyzed. 16 EPA violations found. Free report with contaminant data and filter picks.

Jefferson County, MT: 20 Health Violations — 48/100 (2026)

2026 report: Jefferson County, MT scores 48/100 (Grade D). 8 ZIP codes analyzed. 44 EPA violations found. Free report with contaminant data and filter p...

Judith Basin County, MT: 4 Violations — 51/100 (2026)

2026 report: Judith Basin County, MT scores 51/100 (Grade D). 6 ZIP codes analyzed. 4 EPA violations found. Free report with contaminant data and filter...

Lake County, MT: 2 Health Violations — 49/100 (2026)

2026 report: Lake County, MT scores 49/100 (Grade D). 12 ZIP codes analyzed. 12 EPA violations found. Free report with contaminant data and filter picks.

Lewis and Clark County, MT: 94 Health Violations — 45/100

2026 report: Lewis and Clark County, MT scores 45/100 (Grade D). 15 ZIP codes analyzed. 335 EPA violations found. Free report with contaminant data and ...

Liberty County, MT: 3 Health Violations — 52/100 (2026)

2026 report: Liberty County, MT scores 52/100 (Grade D). 3 ZIP codes analyzed. 19 EPA violations found. Free report with contaminant data and filter picks.

Lincoln County, MT: 3 Health Violations — 58/100 (2026)

2026 report: Lincoln County, MT scores 58/100 (Grade C). 8 ZIP codes analyzed. 14 EPA violations found. Free report with contaminant data and filter picks.

Madison County, MT: 4 Health Violations — 53/100 (2026)

2026 report: Madison County, MT scores 53/100 (Grade D). 11 ZIP codes analyzed. 21 EPA violations found. Free report with contaminant data and filter pi...

McCone County, MT: 5 Violations — 52/100 (2026)

2026 report: McCone County, MT scores 52/100 (Grade D). 2 ZIP codes analyzed. 5 EPA violations found. Free report with contaminant data and filter picks.

Meagher County, MT: 2 Health Violations — 57/100 (2026)

2026 report: Meagher County, MT scores 57/100 (Grade C). 4 ZIP codes analyzed. 14 EPA violations found. Free report with contaminant data and filter picks.

Mineral County, MT: 2 Violations — 54/100 (2026)

2026 report: Mineral County, MT scores 54/100 (Grade D). 5 ZIP codes analyzed. 2 EPA violations found. Free report with contaminant data and filter picks.

Missoula County, MT: 1 Health Violation — 63/100 (2026)

2026 report: Missoula County, MT scores 63/100 (Grade C). 19 ZIP codes analyzed. 44 EPA violations found. Free report with contaminant data and filter p...

Musselshell County, MT: Lead Above EPA Limits — 61/100

2026 report: Musselshell County, MT scores 61/100 (Grade C). 6 ZIP codes analyzed. 5 EPA violations found. Lead above EPA limits. Free report with conta...

Park County, MT: 16 Violations — 63/100 (2026)

2026 report: Park County, MT scores 63/100 (Grade C). 7 ZIP codes analyzed. 16 EPA violations found. Free report with contaminant data and filter picks.

Petroleum County, MT: 4 Violations — 71/100 (2026)

2026 report: Petroleum County, MT scores 71/100 (Grade B). 1 ZIP code analyzed. 4 EPA violations found. Free report with contaminant data and filter picks.

Phillips County, MT: 1 Health Violation — 59/100 (2026)

2026 report: Phillips County, MT scores 59/100 (Grade C). 7 ZIP codes analyzed. 40 EPA violations found. Free report with contaminant data and filter pi...

Pondera County, MT: 6 Health Violations — 53/100 (2026)

2026 report: Pondera County, MT scores 53/100 (Grade D). 4 ZIP codes analyzed. 23 EPA violations found. Free report with contaminant data and filter picks.

Powder River County, MT: 3 Violations — 46/100 (2026)

2026 report: Powder River County, MT scores 46/100 (Grade D). 5 ZIP codes analyzed. 3 EPA violations found. Free report with contaminant data and filter...

Powell County, MT: 8 Violations — 45/100 (2026)

2026 report: Powell County, MT scores 45/100 (Grade D). 4 ZIP codes analyzed. 8 EPA violations found. Free report with contaminant data and filter picks.

Ravalli County, MT: 1 Health Violation — 60/100 (2026)

2026 report: Ravalli County, MT scores 60/100 (Grade C). 9 ZIP codes analyzed. 18 EPA violations found. Free report with contaminant data and filter picks.

Richland County, MT: 9 Health Violations — 48/100 (2026)

2026 report: Richland County, MT scores 48/100 (Grade D). 5 ZIP codes analyzed. 30 EPA violations found. Free report with contaminant data and filter pi...

Roosevelt County, MT: 5 Violations — 58/100 (2026)

2026 report: Roosevelt County, MT scores 58/100 (Grade C). 5 ZIP codes analyzed. 5 EPA violations found. Free report with contaminant data and filter pi...

Rosebud County, MT: 30 Health Violations — 47/100 (2026)

2026 report: Rosebud County, MT scores 47/100 (Grade D). 10 ZIP codes analyzed. 67 EPA violations found. Free report with contaminant data and filter pi...

Sanders County, MT: 8 Violations — 60/100 (2026)

2026 report: Sanders County, MT scores 60/100 (Grade C). 8 ZIP codes analyzed. 8 EPA violations found. Free report with contaminant data and filter picks.

Sheridan County, MT: 11 Violations — 52/100 (2026)

2026 report: Sheridan County, MT scores 52/100 (Grade D). 9 ZIP codes analyzed. 11 EPA violations found. Free report with contaminant data and filter pi...

Silver Bow County, MT: 47 Violations — 55/100 (2026)

2026 report: Silver Bow County, MT scores 55/100 (Grade C). 8 ZIP codes analyzed. 47 EPA violations found. Free report with contaminant data and filter ...

Stillwater County, MT: 13 Violations — 59/100 (2026)

2026 report: Stillwater County, MT scores 59/100 (Grade C). 5 ZIP codes analyzed. 13 EPA violations found. Free report with contaminant data and filter ...

Sweet Grass County, MT Water Safety: 70/100 (2026)

2026 report: Sweet Grass County, MT scores 70/100 (Grade B). 6 ZIP codes analyzed. No EPA violations. Free report with contaminant data and filter picks.

Teton County, MT: 1 Health Violation — 60/100 (2026)

2026 report: Teton County, MT scores 60/100 (Grade C). 7 ZIP codes analyzed. 23 EPA violations found. Free report with contaminant data and filter picks.

Toole County, MT: 5 Health Violations — 51/100 (2026)

2026 report: Toole County, MT scores 51/100 (Grade D). 8 ZIP codes analyzed. 43 EPA violations found. Free report with contaminant data and filter picks.

Treasure County, MT: 7 Health Violations — 56/100 (2026)

2026 report: Treasure County, MT scores 56/100 (Grade C). 5 ZIP codes analyzed. 17 EPA violations found. Free report with contaminant data and filter pi...

Valley County, MT: Lead Above EPA Limits — 47/100 (2026)

2026 report: Valley County, MT scores 47/100 (Grade D). 12 ZIP codes analyzed. 70 EPA violations found. Lead above EPA limits. Free report with contamin...

Wheatland County, MT: 12 Violations — 73/100 (2026)

2026 report: Wheatland County, MT scores 73/100 (Grade B). 4 ZIP codes analyzed. 12 EPA violations found. Free report with contaminant data and filter p...

Wibaux County, MT: 1 Health Violation — 69/100 (2026)

2026 report: Wibaux County, MT scores 69/100 (Grade C). 1 ZIP code analyzed. 17 EPA violations found. Free report with contaminant data and filter picks.

Yellowstone County, MT: 71 Health Violations — 68/100 (2026)

2026 report: Yellowstone County, MT scores 68/100 (Grade C). 26 ZIP codes analyzed. 496 EPA violations found. Free report with contaminant data and filt...