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Idaho

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726 systems serving 1,063,278 people

This drinking water quality report shows results of tests conducted by water utilities in Idaho, provided to the Environmental Working Group (EWG) by the Department of Health and Welfare- Division of Environmental Quality. 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.

	Chemicals	Water Utilities	Population Served
Detected Chemicals	61	726	1,057,640
Exceed health guidelines*	40	508	953,644
Exceed Legal Limits*	18	134	443,342
Unregulated chemicals detected	5	6	188,254
* 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.

40 Contaminants Exceeding Health Based Limits

Contaminants detected in Idaho drinking water above health guidelines, according to an Environmental Working Group analysis of data obtained from state water authorities

Contaminant	Population		Number of Systems
	At Any Level	Above Health Limits	At Any Level	Above Health Limits
Arsenic (total)	756,833	756,833	298	298
Alpha particle activity (excl radon and uranium)	590,518	590,518	84	84
Total haloacetic acids (HAAs)	644,199	571,327	149	142
Radium-228	542,818	542,818	94	94
Combined Radium (-226 & -228)	531,680	531,680	80	80
Bromoform	480,493	480,493	18	18
Radium-226	475,279	475,279	67	67
Total trihalomethanes (TTHMs)	836,618	390,351	233	86
Dibromochloromethane	472,591	383,937	20	16
Bromodichloromethane	382,516	382,516	29	29

Water Utilities in Idaho Reporting Chemicals Exceeding Health Guidelines

Water utilities in Idaho reporting chemicals exceeding health guidelines, according to an Environmental Working Group analysis of data obtained from state water authorities, include:

System	Population	Chemicals tested	Chemicals found	Chemicals exceeding health guidelines
United Water Idaho Inc	185,787	93	32	21
Meridian Water Dept	46,500	84	23	13
City of Pocatello	53,932	75	18	12
Capitol Water Corp	7,400	75	13	10
Mountain Home Air Force Base	7,500	66	12	8
City of Idaho Falls	51,507	76	14	7
City of Twin Falls	36,000	71	14	7
Riverside Trailer Court	35	67	10	7
Wilderness Ranch Owners Association Inc	525	75	14	7
Belmont Heights	190	60	11	7
City of Weiser	5,343	65	9	7
City of Fruitland	4,116	73	12	7
City of Nampa	63,800	83	18	7
Caldwell Housing Authority	1,100	76	12	7
Blackhawk Estates	100	61	11	6
Falls Water Company Inc	10,900	54	13	6
Comore Loma	620	78	10	6
Meander Point Subd	140	34	7	6
Elm Park Water System	120	34	7	6
Jug Mountain Ranch Subdivision	40	70	11	6

Sources of Idaho Drinking Water Contaminants

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

61	Total Contaminants Detected (2004 - 2009)
13	Agricultural Pollutants (pesticides, fertilizer, factory farms) Arsenic (total), Cyanide, Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Phosphorus, Endothall, Simazine, Atrazine, 2,4-D, Ethylene dibromide (EDB), Ethylbenzene
18	Sprawl and Urban Pollutants (road runoff, lawn pesticides, human waste) Nitrate, Copper, Nitrate & nitrite, Lead (total), Arsenic (total), Tetrachloroethylene, Nitrite, Xylenes (total), Cadmium (total), Antimony (total), Mercury (total inorganic), Dichloromethane (methylene chloride), Cyanide, Di(2-Ethylhexyl) adipate, Phosphorus, 2,4-D, bis(2-ethylhexyl) phthalate, 2,3,7,8-TCDD (Dioxin)
44	Industrial Pollutants Aluminum, Bromide, Arsenic (total), Barium (total), Cadmium (total), Chromium (total), Cyanide, Lead (total), Manganese, Mercury (total inorganic), Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Antimony (total), Beryllium (total), Thallium (total), Phosphorus, Asbestos, Di(2-Ethylhexyl) adipate, Di(2-ethylhexyl) phthalate, Hexachlorocyclopentadiene, 2,3,7,8-TCDD (Dioxin), bis(2-ethylhexyl) phthalate, Ethylene dibromide (EDB), Xylenes (total), Dichloromethane (methylene chloride), trans-1,2-Dichloroethylene, 1,2-Dichloroethane, Carbon tetrachloride, Trichloroethylene, 1,1,2-Trichloroethane, Tetrachloroethylene, Toluene, Ethylbenzene, Alpha particle activity (excl radon and uranium), Alpha particle activity (incl. radon & uranium), Combined Uranium (mg/L), Combined Radium (-226 & -228), Radium-226, Radium-228, Alpha particle activity, 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, Di(2-ethylhexyl) phthalate, Cadmium (total), Asbestos
24	Naturally Occurring (naturally present but increased for lands denuded by sprawl, agriculture, or industrial development) Nitrate, Copper, Nitrate & nitrite, Barium (total), Lead (total), Arsenic (total), Manganese, Radium-228, Radium-226, Alpha particle activity, 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), Aluminum, Selenium (total), Nitrite, Bromide, Mercury (total inorganic), Cyanide, Phosphorus
6	Unregulated Contaminants EPA has not established a maximum legal limit in tapwater for these contaminants Bromide, Lead (total), Phosphorus, bis(2-ethylhexyl) phthalate, Uranium-234 (pCi/L), Uranium-238 (pCi/L)

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Testing Summary for Idaho

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

Contaminants reported as tested by water suppliers in Idaho		144
	Contaminants tested due to federal law:	89
	Contaminants tested in addition to those required by federal law:	55

Violation Summary for Idaho

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

Violation Type	Number of Violations
Failure to monitor regularly	1,679
Failure to monitor, Routine Major (Coliform bacteria)	500
Maximum contaminant level, Monthly (Coliform bacteria)	421
Monitoring and Reporting Disinfection Byproduct Rule	421
Over maximum contaminant level, Average	407
Failure to monitor, Routine Minor (Coliform bacteria)	134
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination)	106
Over maximum contaminant level, Single Sample	96
Treatment Technique (Surface Water Treatment Rule)	74
Follow-up and Routine Tap Sampling	51
Filter Turbidity Reporting	23
Failure to monitor, Repeat Major (Coliform bacteria)	22
Initial Tap Sampling for Lead and Copper	21
Failure to monitor, Repeat Minor (Coliform bacteria)	12
Maximum contaminant level, Acute (Coliform bacteria)	10
Failure to notify public of violation	3
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination)	2
Failure to Filter (Surface Water Treatment Rule)	1
Optimal Corrosion Control Treatment Study Recommendation	1
Non-Acute maximum residual disinfectant level	1