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) 373,607 370,181 141 130
Total trihalomethanes (TTHMs) 384,806 284,279 152 81
Radium-228 227,010 227,010 146 146
Alpha particle activity (excl radon and uranium) 147,268 147,268 78 78
Combined Radium (-226 & -228) 136,330 136,330 65 65
Radium-226 135,855 135,855 66 66
Bromate 86,207 86,207 3 3
Combined Uranium (mg/L) 16,935 16,935 14 14
Alpha particle activity (incl. radon & uranium) 161,399 11,971 126 13
Nitrate & nitrite 236,111 6,089 137 2

  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.

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

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

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

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

27 Industrial 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)

13 Water 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

21 Naturally 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)

2 Unregulated 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 Wyoming 105
  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 Type Number of Violations
Failure to monitor regularly 593
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 Report 68
Monitoring and Reporting Disinfection Byproduct Rule 65
Failure to monitor, Routine Minor (Coliform bacteria) 25
Follow-up and Routine Tap Sampling 24
Initial Tap Sampling for Lead and Copper 19
Inadequate reporting of information to the public 15
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, Average 5
Excess Turbidity at 0.3 NTU 5
Failure to monitor, Repeat Major (Coliform bacteria) 5
Treatment Technique Precursor Removal 2
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination) 2
Initial Water Quality Parameter Monitoring and Reporting 1
Over maximum contaminant level, Single Sample 1
Failure to Filter (Surface Water Treatment Rule) 1
Excess Turbidity at 1 NTU 1
Filter Turbidity Reporting 1

Sources : EWG (Environmental Working Group)