The Power of Information

National Drinking Water Database


212 systems serving 400,966 people

This drinking water quality report shows results of tests conducted by water utilities in Wyoming, provided to the Environmental Working Group (EWG) by the Wyoming Environmental Protection Agency. 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.

25 Contaminants Exceeding Health Based Limits

Contaminants detected in Wyoming 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)373,607370,181141130
Total trihalomethanes (TTHMs)384,806284,27915281
Alpha particle activity (excl radon and uranium)147,268147,2687878
Combined Radium (-226 & -228)136,330136,3306565
Combined Uranium (mg/L)16,93516,9351414
Alpha particle activity (incl. radon & uranium)161,39911,97112613
Nitrate & nitrite236,1116,0891372

Water Utilities in Wyoming Reporting Chemicals Exceeding Health Guidelines

Water utilities in Wyoming 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
Torrington Mun. Water System5,600831310
Town of Lyman2,20382129
Stone Creek4082128
Burns Bd. of Public Utilities25466178
Town of Pine Bluffs1,1536398
Yellowstone NP Old Faithful1506687
Bennor Subdivision1746687
Fairway Estates10081117
Warm Springs Water District558097
Town of LA Grange33480117
Town of Yoder Water System1656697
Town of Douglas5,40082127
Little America Hotels & Resorts, Inc- Wy2,00087117
Rock Springs/Green River Jp2586117
North End Water Users4897987
Cheyenne Board Pub Utilities58,18286137
Yellowstone NP Mammoth Hot Spg3006796
Ridge Way Community Well Association606686
Cook Road Water District2567786
Meadow Park Homeowners Assoc1007896

Sources of Wyoming Drinking Water Contaminants

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

41Total Contaminants Detected (2004 - 2008)
8Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Arsenic (total), Cyanide, Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), o-Dichlorobenzene, 1,2-Dichloropropane

7Sprawl and Urban Pollutants
(road runoff, lawn pesticides, human waste)

Arsenic (total), Copper, Cyanide, Nitrate & nitrite, Nitrate, Nitrite, Dichloromethane (methylene chloride)

27Industrial Pollutants

Bromide, Arsenic (total), Chlorite, Barium (total), Chromium (total), Cyanide, Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Di(2-ethylhexyl) phthalate, Dichloromethane (methylene chloride), 1,2-Dichloroethane, 1,1,1-Trichloroethane, Carbon tetrachloride, 1,2-Dichloropropane, Toluene, 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, Gross beta particle activity (dissolved), Combined Uranium (pCi/L), Gross beta particle activity (pCi/L)

13Water 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, Chlorite, Di(2-ethylhexyl) phthalate, Bromate

21Naturally Occurring
(naturally present but increased for lands denuded by sprawl, agriculture, or industrial development)

Nitrate, Copper, Nitrate & nitrite, Barium (total), Arsenic (total), 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), Selenium (total), Nitrite, Radon, Bromide, Cyanide, Uranium-238, Gross beta particle activity (dissolved)

2Unregulated Contaminants
EPA has not established a maximum legal limit in tapwater for these contaminants

Bromide, Radon

Testing Summary for Wyoming

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

Contaminants reported as tested by water suppliers in Wyoming105
 Contaminants tested due to federal law: 89
 Contaminants tested in addition to those required by federal law: 16

Violation Summary for Wyoming

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

Violation TypeNumber of Violations
Failure to monitor regularly593
Failure to monitor, Routine Major (Coliform bacteria)108
Maximum contaminant level, Monthly (Coliform bacteria)72
Failure to report information to the public or state agency in the Consumer Confidence Report68
Monitoring and Reporting Disinfection Byproduct Rule65
Failure to monitor, Routine Minor (Coliform bacteria)25
Follow-up and Routine Tap Sampling24
Initial Tap Sampling for Lead and Copper19
Inadequate reporting of information to the public15
Treatment Technique (Surface Water Treatment Rule)7
Failure to monitor, Repeat Minor (Coliform bacteria)6
Maximum contaminant level, Acute (Coliform bacteria)5
Over maximum contaminant level, Average5
Excess Turbidity at 0.3 NTU5
Failure to monitor, Repeat Major (Coliform bacteria)5
Treatment Technique Precursor Removal2
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination)2
Over maximum contaminant level, Single Sample1
Failure to Filter (Surface Water Treatment Rule)1
Excess Turbidity at 1 NTU1
Filter Turbidity Reporting1
Initial Water Quality Parameter Monitoring and Reporting1