Diquat
City of Napa
Diquat is a herbicide used on potato crops and aquatic weeds.
15
Samples
0
Samples exceeding legal limit (MCL)
0
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2013 | N/A | 0 | 0 | N/A |
| 2014 | ND | 3 | 0 | ND |
| 2015 | ND | 3 | 0 | ND |
| 2016 | ND | 2 | 0 | ND |
| 2017 | ND | 3 | 0 | ND |
| 2018 | ND | 2 | 0 | ND |
| 2019 | ND | 2 | 0 | 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 |
|---|---|---|
| 2014-07-09 | 9590-005-1145 | ND |
| 2014-07-09 | 9590-006-1245 | ND |
| 2014-07-09 | 9590-007-0925 | ND |
| 2015-07-21 | 9590-005-1120 | ND |
| 2015-07-21 | 9590-006-1415 | ND |
| 2015-07-21 | 9590-007-0940 | ND |
| 2016-07-27 | 9590-006-1245 | ND |
| 2016-07-27 | 9590-006-1545 | ND |
| 2017-07-20 | 9590-006-1330 | ND |
| 2017-07-20 | 9590-007-1050 | ND |
| 2017-09-13 | 9590-005-0840 | ND |
| 2018-07-11 | 9590-006-1015 | ND |
| 2018-07-11 | 9590-007-1200 | ND |
| 2019-07-10 | 1644-007-0830 | ND |
| 2019-07-10 | 1644-007-1200 | ND |