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EWG's Tap Water Database — 2019 UPDATE

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Diquat

City of Lewiston

Diquat is a herbicide used on potato crops and aquatic weeds.

 

21

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012ND20ND
2013ND60ND
2014ND10ND
2015ND60ND
2016ND50ND
2017ND10ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 6 ppb

The EWG Health Guideline of 6 ppb for diquat was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cataracts.

EPA Maximum Contaminant
Level (MCL) 20 ppb

The legal limit for diquat, established in 1992, was based on a toxicity study in laboratory animals conducted in the 1980s.

ppb = parts per billion

All test results

Date Lab ID Result
2012-04-03S59257ND
2012-05-01S59777ND
2013-02-27S130228026-001ND
2013-08-21S130822058-001ND
2013-08-21S130822058-005ND
2013-08-21S130822058-004ND
2013-08-21S130822058-003ND
2013-08-21S130822058-002ND
2014-02-25S140226039-001ND
2015-01-21S2150122025-001ND
2015-07-22S150723044-003ND
2015-07-22S150723044-002ND
2015-07-22S150723044-001ND
2015-08-19S150819036-001ND
2015-08-19S150819036-002ND
2016-02-09S160209050-002ND
2016-04-06S160407008-001ND
2016-04-06S160407008-002ND
2016-04-06S160407008-003ND
2016-05-16S160518056-001ND
2017-03-28S170328050-001ND