Diquat
Pierce, City of
Diquat is a herbicide used on potato crops and aquatic weeds.
12
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 | N/A | 0 | 0 | N/A |
| 2019 | ND | 2 | 0 | ND |
| 2020 | ND | 4 | 0 | ND |
| 2021 | ND | 4 | 0 | ND |
| 2022 | ND | 1 | 0 | ND |
| 2023 | ND | 1 | 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 |
|---|---|---|
| 2019-09-09 | 634552 | ND |
| 2019-10-15 | 638482 | ND |
| 2020-01-21 | 651125 | ND |
| 2020-04-20 | 667161 | ND |
| 2020-07-20 | 681483 | ND |
| 2020-11-09 | 699971 | ND |
| 2021-02-18 | 713160 | ND |
| 2021-02-18 | 713161 | ND |
| 2021-02-18 | 713162 | ND |
| 2021-10-12 | 763941 | ND |
| 2022-10-17 | 828375 | ND |
| 2023-10-16 | 891622 | ND |