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Public water system record

City of Chinook

Serves Chinook, Blaine County, MT · 1,300 people served

Federal records show 4 health-based violations and no monitoring/reporting issues for City of Chinook in the last ten years. The most serious issue in this window was a resolved Haloacetic Acids (HAA5) violation.

  • MT0000174
  • CHINOOK
  • MT
  • 1,300 served

System profile

Source water Surface water
ZIP 59532
EPA system ID MT0000174

Verify this system on EPA ECHO →

Health-based violations, last 10 years
4
Resolved
4
Unresolved
0
Any acute record
No
Monitoring issues, last 10 years
0

Key facts

  • City of Chinook draws water from 1 surface water intake.
  • Highest measured level in the last 10 years: Haloacetic Acids (HAA5), 0.079 mg/L, federal limit 0.06 mg/L (1.3 times the limit), 2025.
  • Record on file since 1993, with 11 health-based violations before October 19, 2016.
  • Lead pipe inventory: 3 lead and 1 unknown out of 840 service lines.

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Health-based violations

Since October 2016

Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.

Contaminant Rule family Start date Status Acute
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.073 mg/L, federal limit 0.06 mg/L (1.2 times the limit)
 220 Oct 1, 2025 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.077 mg/L, federal limit 0.06 mg/L (1.3 times the limit)
 220 Jul 1, 2025 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.079 mg/L, federal limit 0.06 mg/L (1.3 times the limit)
 220 Apr 1, 2025 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.071 mg/L, federal limit 0.06 mg/L (1.2 times the limit)
 220 Jan 1, 2025 Resolved No

Full record since 1993

EPA's records for City of Chinook go back to 1993. Before October 19, 2016 they list 11 health-based violations (11 resolved) and 11 monitoring or reporting violations.

Violations that began in Health-based Monitoring and reporting
1990s 9 7
2000s 1 3
2010 to October 18, 2016 1 1
2020s 4 0

Most recent health-based violation before October 19, 2016: Haloacetic Acids (HAA5), began April 2011, Resolved.

Show all 11 health-based violations before October 19, 2016
Contaminant Start date Status
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 62.3 µg/L, federal limit 60 µg/L (at or just above the limit)
 Apr 1, 2011 Resolved
DICHLOROMETHANE
Contaminant limit exceeded
Measured 0.01 mg/L, federal limit 0.005 mg/L (2 times the limit)
 Jan 1, 2000 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Jan 1, 1999 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Nov 1, 1997 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Oct 1, 1997 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Sep 1, 1997 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Aug 1, 1997 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Jun 1, 1995 Resolved
Surface Water Treatment Rule
Treatment technique failure
 May 1, 1995 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Apr 1, 1995 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Feb 1, 1995 Resolved

What the violations mean

Haloacetic Acids (HAA5)

4 incidents

Haloacetic acid byproducts exceeded the federal limit

Long-term exposure to HAAs may increase cancer risk

Where the water comes from

City of Chinook draws water from 1 surface water intake. 1 other community water system buys water from City of Chinook.

Community systems that buy water from it

Annual water quality report

City of Chinook must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.

Where the state allows it, systems serving fewer than 10,000 people may publish the report in a local newspaper or news site instead of mailing it, and must provide a copy on request.

Find a posted report with EPA's Consumer Confidence Report search

Testing your own water

To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by Montana.

Certified drinking water labs by state EPA guidance for private wells