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National Drinking Water Database


Arsenic (total) in Wyoming


Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides. [read more]

The Most Polluted Communities in Wyoming

8 water utilities reported detecting Arsenic (total) in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Arsenic (total) level

RankSystem Population Served Positive test results of total reported tests Average Level
(Range)
1Lance Creek Water District
Lance Creek, WY
356 of 719.29 ppb
(0 to 30 ppb)
2Meadow Park Homeowners Assoc
Evanston, WY
1004 of 416.67 ppb
(10 to 25 ppb)
3Fairway Estates
Douglas, WY
10011 of 1110 ppb
(10 ppb)
4Town of Lyman
Lyman, WY
2,2039 of 109 ppb
(0 to 10 ppb)
5Yellowstone NP Old Faithful
Yellowstone Np, WY
1506 of 127.5 ppb
(0 to 30 ppb)
6Town of LA Barge
La Barge, WY
5101 of 25 ppb
(0 to 10 ppb)
7Town of LA Grange
La Grange, WY
3344 of 93.33 ppb
(0 to 10 ppb)
8Warm Springs Water District
Dubois, WY
554 of 181.39 ppb
(0 to 10 ppb)

Health Based Limits for Arsenic (total)

StandardDescriptionLevel
Maximum Contaminant Limit Goal (MCLG)A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.0 ppb
California Public Health GoalsDefined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.<0.01 ppb
EPA Human Health Water Quality CriteriaWater quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.0.02 ppb
One in one million (10-6) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 1,000,000. Source: U.S. Environmental Protection Agency.0.02 ppb
One in ten thousand (10-4) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.2 ppb
Maximum Contaminant Limit (MCL)The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.10 ppb
Drinking Water Equivalent LevelA lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.10 ppb

Violation Summary for Arsenic (total) in 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 regularly5
Over maximum contaminant level, Single Sample1