Diquat
City of Lewiston
Diquat is a herbicide used on potato crops and aquatic weeds.
21
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 | 1 | 0 | ND |
| 2015 | ND | 6 | 0 | ND |
| 2016 | ND | 5 | 0 | ND |
| 2017 | ND | 1 | 0 | ND |
| 2018 | ND | 4 | 0 | ND |
| 2019 | ND | 4 | 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 |
|---|---|---|
| 2014-02-25 | S140226039-001 | ND |
| 2015-01-21 | S2150122025-001 | ND |
| 2015-07-22 | S150723044-003 | ND |
| 2015-07-22 | S150723044-002 | ND |
| 2015-07-22 | S150723044-001 | ND |
| 2015-08-19 | S150819036-002 | ND |
| 2015-08-19 | S150819036-001 | ND |
| 2016-02-09 | S160209050-002 | ND |
| 2016-04-06 | S160407008-001 | ND |
| 2016-04-06 | S160407008-003 | ND |
| 2016-04-06 | S160407008-002 | ND |
| 2016-05-16 | S160518056-001 | ND |
| 2017-03-28 | S170328050-001 | ND |
| 2018-02-21 | S180221045-001 | ND |
| 2018-02-22 | S180223004-001 | ND |
| 2018-12-13 | S181213011-002 | ND |
| 2018-12-13 | S181213011-001 | ND |
| 2019-01-24 | S190124017-001 | ND |
| 2019-04-23 | S190423067-002 | ND |
| 2019-04-23 | S190423067-001 | ND |
| 2019-08-14 | S190814080-001 | ND |