The Power of Information

National Drinking Water Database


684 systems serving 712,991 people

This drinking water quality report shows results of tests conducted by water utilities in Montana, provided to the Environmental Working Group (EWG) by the Montana Department of Environmental Quality. It is part of EWG's national database that includes 47,667 drinking water utilities and 20 million test results from 45 states and the District of Columbia. Water utilities nationwide detected more than 300 pollutants between 2004 and 2009. More than half of these chemicals are unregulated, legal in any amount. Despite this widespread contamination, the federal government invests few resources in protecting rivers, reservoirs, and groundwater from pollution in the first place. The information below summarizes drinking water quality for this state.

Water Utilities
Population Served
Detected Chemicals
Exceed health guidelines*
Exceed Legal Limits*
Unregulated chemicals detected
* Water utilities are noted as exceeding the legal limit if any test is above the maximum contaminant level (MCL). Most MCLs are based on annual averages so exceeding the MCL for one test does not necessarily indicate that the system is out of compliance.

30 Contaminants Exceeding Health Based Limits

Contaminants detected in Montana drinking water above health guidelines, according to an Environmental Working Group analysis of data obtained from state water authorities

Number of Systems
At Any Level Above Health Limits At Any Level Above Health Limits
Total haloacetic acids (HAAs)568,674553,372214192
Lead (total)504,440504,440541541
Dichloroacetic acid489,939489,939131131
Arsenic (total)456,405456,405241241
Total trihalomethanes (TTHMs)571,260426,534229130
Trichloroacetic acid462,046332,71913634

Water Utilities in Montana Reporting Chemicals Exceeding Health Guidelines

Water utilities in Montana reporting chemicals exceeding health guidelines, according to an Environmental Working Group analysis of data obtained from state water authorities, include:

Chemicals tested
Chemicals found
Chemicals exceeding
health guidelines
Town of Hysham2621192015
Forest Park Water Users Association4001232212
Town of Flaxville821151712
Mountain Water Company56,3351232112
Town of Melstone1701181912
Laurel Municipal Water System6,3391061612
Helena Water System31,0051171812
Town of Geraldine300291912
City of Forsyth1,9441202012
Town of Chester9501122012
Stock Farm The1001201611
City of Wolf Point3,9151171611
Wilsall Water District2501141511
City of Glendive4,8061121611
Gardiner Park Co Water Dist7001121711
City of Colstrip2,0001181511
Brady County Water and Sewer District2251151811
Red Cliff Estates Hoa361041810
North Havre County Water Dist901061510
Seville Colony1101161610

Sources of Montana Drinking Water Contaminants

The contaminants identified in Montana drinking water come from a wide variety of sources, including agriculture, industry, water treatment plants, and polluted storm runoff from urban areas.

67Total Contaminants Detected (2004 - 2009)
13Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Arsenic (total), Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Phosphorus, Dalapon, Picloram, Atrazine, Dacthal, 2,4-D, p-Dichlorobenzene, Ethylbenzene

22Sprawl and Urban Pollutants
(road runoff, lawn pesticides, human waste)

Nitrate, Copper, Nitrate & nitrite, Lead (total), Arsenic (total), Tetrachloroethylene, Nitrite, Xylenes (total), Dalapon, Cadmium (total), Antimony (total), Mercury (total inorganic), Dichloromethane (methylene chloride), o-Xylene, Trichlorofluoromethane, Dacthal, p-Dichlorobenzene, Di(2-Ethylhexyl) adipate, Phosphorus, 2,4-D, Naphthalene, n-Propylbenzene

48Industrial Pollutants

Aluminum, Arsenic (total), Barium (total), Cadmium (total), Chromium (total), Lead (total), Manganese, Mercury (total inorganic), Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Antimony (total), Beryllium (total), Thallium (total), Phosphorus, Di(2-Ethylhexyl) adipate, Di(2-ethylhexyl) phthalate, Hexachlorocyclopentadiene, Chloromethane, Chloroethane, Trichlorofluoromethane, Naphthalene, Pentachlorophenol, Dibromomethane, 1,2,4-Trimethylbenzene, 1,3,5-Trimethylbenzene, Xylenes (total), Dichloromethane (methylene chloride), p-Dichlorobenzene, 1,1-Dichloroethylene, Carbon tetrachloride, Tetrachloroethylene, Toluene, Ethylbenzene, Isopropylbenzene, Styrene, o-Xylene, n-Propylbenzene, Alpha particle activity (excl radon and uranium), Alpha particle activity (incl. radon & uranium), Combined Uranium (mg/L), Uranium-238, Combined Radium (-226 & -228), Radium-226, Radium-228, Combined Uranium (pCi/L), Gross beta particle activity (pCi/L)

17Water Treatment and Distribution Byproducts
(pipes and fixtures, treatment chemicals and byproducts)

Total trihalomethanes (TTHMs), Total haloacetic acids (HAAs), Chloroform, Bromodichloromethane, Dibromochloromethane, Dichloroacetic acid, Trichloroacetic acid, Bromoform, Dibromoacetic acid, Monochloroacetic acid, Bromochloroacetic acid, Monobromoacetic acid, Di(2-ethylhexyl) phthalate, Cadmium (total), Chloromethane, Dibromomethane, Chloroethane

24Naturally Occurring
(naturally present but increased for lands denuded by sprawl, agriculture, or industrial development)

Nitrate, Copper, Nitrate & nitrite, Barium (total), Lead (total), Arsenic (total), Manganese, Radium-228, Radium-226, Alpha particle activity (excl radon and uranium), Combined Radium (-226 & -228), Gross beta particle activity (pCi/L), Combined Uranium (pCi/L), Chromium (total), Alpha particle activity (incl. radon & uranium), Combined Uranium (mg/L), Aluminum, Selenium (total), Nitrite, Mercury (total inorganic), Chloromethane, Uranium-238, Phosphorus, Silicon

14Unregulated Contaminants
EPA has not established a maximum legal limit in tapwater for these contaminants

Lead (total), Phosphorus, Dacthal, Chloromethane, Chloroethane, Trichlorofluoromethane, Naphthalene, Dibromomethane, 1,2,4-Trimethylbenzene, 1,3,5-Trimethylbenzene, Bromochloroacetic acid, Isopropylbenzene, n-Propylbenzene, Silicon

Testing Summary for Montana

The federal government has set standards for some of the pollutants found in tap water supplies.

Contaminants reported as tested by water suppliers in Montana152
 Contaminants tested due to federal law: 86
 Contaminants tested in addition to those required by federal law: 66

Violation Summary for Montana

Data from the U.S. Environmental Protection Agency includes the following violations of federal standards in Montana since 2004

Violation TypeNumber of Violations
Failure to monitor regularly3,609
Failure to monitor, Routine Major (Coliform bacteria)475
Failure to report information to the public or state agency in the Consumer Confidence Report374
Monitoring and Reporting Disinfection Byproduct Rule373
Maximum contaminant level, Monthly (Coliform bacteria)317
Follow-up and Routine Tap Sampling257
Initial Tap Sampling for Lead and Copper132
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination)105
Initial Water Quality Parameter Monitoring and Reporting92
Over maximum contaminant level, Average89
Over maximum contaminant level, Single Sample75
Filter Turbidity Reporting62
Failure to monitor, Routine Minor (Coliform bacteria)55
Treatment Technique (Surface Water Treatment Rule)51
Inadequate reporting of information to the public50
Excess Turbidity at 0.3 NTU47
Excess Turbidity at 1 NTU43
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination)33
Failure to monitor, Repeat Major (Coliform bacteria)30
Maximum contaminant level, Acute (Coliform bacteria)13
Optimal Corrosion Control Treatment Study Recommendation12
Public Education11
Initial, Follow-up, or Routine Source Water Treatment Monitoring and Reporting7
Failure to monitor, Repeat Minor (Coliform bacteria)4
Treatment Technique (Filter Backwash Reporting Rule)? 41 H "Treatment Technique (Surface Water Treatment Rule)1
Failure to Filter (Surface Water Treatment Rule)1
Public Notification Violation for National Primary Drinking Water Regulations1