Diquat

Valley Water Systems, Inc.

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
2013	N/A	0	N/A
2014	N/A	0	N/A
2015	N/A	0	N/A
2016	ND	4	ND
2017	N/A	0	N/A
2018	N/A	0	N/A
2019	ND	4	ND

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
2016-01-04	16010404-001-SOC	ND
2016-01-04	16010404-002-SOC	ND
2016-07-05	16070504-001-SOC	ND
2016-07-05	16070504-002-SOC	ND
2019-03-05	19030501-001-SOC	ND
2019-03-05	19030502-001-SOC	ND
2019-08-01	19080111-001-SOC	ND
2019-08-01	19080111-002-SOC	ND