Diquat

Yorktown Water

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

Samples

Samples exceeding legal limit (MCL)

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Range of results
2014	ND	14	ND
2015	N/A	0	N/A
2016	N/A	0	N/A
2017	ND	14	ND
2018	N/A	0	N/A
2019	N/A	0	N/A

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
2014-08-11	14226000508	ND
2014-08-11	14226000708	ND
2014-08-11	14226000308	ND
2014-08-11	14226000108	ND
2014-08-11	14226000208	ND
2014-08-11	14226000408	ND
2014-08-11	14226000608	ND
2014-10-21	14296009808	ND
2014-10-21	14296009708	ND
2014-10-21	14296009408	ND
2014-10-21	14296009908	ND
2014-10-21	14296009508	ND
2014-10-21	14296010008	ND
2014-10-21	14296009608	ND
2017-08-07	17222000907	ND
2017-08-07	17222001107	ND
2017-08-07	17222001207	ND
2017-08-07	17222001307	ND
2017-08-07	17222001505	ND
2017-08-07	17222001605	ND
2017-08-07	17222001007	ND
2017-10-17	17292005608	ND
2017-10-17	17292005308	ND
2017-10-17	17292005708	ND
2017-10-17	17292005408	ND
2017-10-17	17292005508	ND
2017-10-17	17292005808	ND
2017-10-17	17292005908	ND