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National Drinking Water Database


Arsenic (total) in Idaho


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 Idaho

298 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)
1Maverick Subd Lasher Construction
Caldwell, ID
902 of 230 ppb
(30 ppb)
2Shari Hill Estates
Marsing, ID
397 of 727.14 ppb
(22 to 30 ppb)
3Loma Linda Water Corp
Fruitland, ID
7013 of 1325.66 ppb
(13.6 to 30 ppb)
4Sunnyridge I Subd
Nampa, ID
435 of 525.6 ppb
(22 to 30 ppb)
5Valley View Water
Nampa, ID
575 of 522.8 ppb
(21 to 24 ppb)
6D and S Purple Sage Ranchettes
Caldwell, ID
709 of 921.11 ppb
(5 to 26 ppb)
7City of Castleford
Castleford, ID
27511 of 1120.64 ppb
(18 to 24 ppb)
8Edgemont Subd
Emmett, ID
408 of 820.63 ppb
(18 to 30 ppb)
9Grandview Water and Sewer Assn
Grand View, ID
35515 of 1518.83 ppb
(15 to 22 ppb)
10East Lizard Butte Water Corp
Marsing, ID
9519 of 1918.61 ppb
(15 to 22 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 Idaho

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

Violation TypeNumber of Violations
Over maximum contaminant level, Average217
Failure to monitor regularly58
Over maximum contaminant level, Single Sample51