Diquat
Guilford Water Authority
Diquat is a herbicide used on potato crops and aquatic weeds.
20
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 | 3 | 0 | ND |
| 2019 | ND | 1 | 0 | ND |
| 2020 | ND | 6 | 0 | ND |
| 2021 | N/A | 0 | 0 | N/A |
| 2022 | N/A | 0 | 0 | N/A |
| 2023 | ND | 10 | 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 |
|---|---|---|
| 2018-05-29 | 8055384-01 | ND |
| 2018-09-04 | 8091925-01 | ND |
| 2018-12-11 | 8122846-01 | ND |
| 2019-03-05 | 9032320-01 | ND |
| 2020-06-09 | 22559579.00 | ND |
| 2020-06-09 | 22559549.00 | ND |
| 2020-06-09 | 22559519.00 | ND |
| 2020-09-09 | 23136521.00 | ND |
| 2020-09-09 | 23136547.00 | ND |
| 2020-09-09 | 23136577.00 | ND |
| 2023-05-17 | 29053245.00 | ND |
| 2023-05-17 | 29053261.00 | ND |
| 2023-05-17 | 29053277.00 | ND |
| 2023-05-24 | 29053446.00 | ND |
| 2023-05-24 | 29053413.00 | ND |
| 2023-07-18 | 29651137.00 | ND |
| 2023-07-18 | 29651228.00 | ND |
| 2023-07-18 | 29651149.00 | ND |
| 2023-08-01 | 29651202.00 | ND |
| 2023-08-29 | 29651294.00 | ND |