The Power of Information

National Drinking Water Database


Arsenic (total) in Montana


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 Montana

241 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)
1Spring Tree Ridge
MT
751 of 120 ppb
(20 ppb)
2Carter Chouteau Co Water Dist
Carter, MT
2005 of 712.87 ppb
(0 to 30 ppb)
3Pine Crest TR Pk
Pray, MT
547 of 712.71 ppb
(9.5 to 20 ppb)
4Firelight Meadows Llc
Big Sky, MT
3501 of 112.67 ppb
(12.67 ppb)
5Birch Creek Colony
Valier, MT
1106 of 611.67 ppb
(10 to 20 ppb)
6Big Spur TR Ct
Livingston, MT
3014 of 1410.03 ppb
(10 to 10.4 ppb)
7Town of Big Sandy
Big Sandy, MT
7001 of 110 ppb
(10 ppb)
8Jefferson Tracts Assoc Inc
Clancy, MT
802 of 210 ppb
(10 ppb)
9North Shore Estates Hoa
Thompson Falls, MT
655 of 510 ppb
(10 ppb)
10East Gate Work Camp
Gardiner, MT
831 of 110 ppb
(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 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 regularly58
Over maximum contaminant level, Average15
Over maximum contaminant level, Single Sample1