Diquat
St John Water District 1
Diquat is a herbicide used on potato crops and aquatic weeds.
16
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 |
|---|---|---|---|---|
| 2018 | ND | 4 | 0 | ND |
| 2019 | ND | 4 | 0 | ND |
| 2020 | ND | 2 | 0 | ND |
| 2021 | ND | 2 | 0 | ND |
| 2022 | ND | 2 | 0 | ND |
| 2023 | ND | 2 | 0 | ND |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
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 |
|---|---|---|
| 2018-01-23 | 35370117004 | ND |
| 2018-01-23 | 35370117004 | ND |
| 2018-07-17 | 35405084001 | ND |
| 2018-07-17 | 35405084001 | ND |
| 2019-01-22 | 35444040001 | ND |
| 2019-01-22 | 35444040001 | ND |
| 2019-07-25 | 35485228001 | ND |
| 2019-07-25 | 35485228001 | ND |
| 2020-03-05 | 35535517001 | ND |
| 2020-10-22 | 35587106001 | ND |
| 2021-01-28 | 35608068001 | ND |
| 2021-11-18 | 35679380001 | ND |
| 2022-02-02 | 35694871001 | ND |
| 2022-09-15 | 35747517001 | ND |
| 2023-03-20 | 35787603001 | ND |
| 2023-11-28 | 35844327001 | ND |