Diquat
Polk City Water Supply
NOTE: Polk City Water Supply purchases water from Des Moines Water Works which is required to test for diquat. Sample information shown below was taken by Des Moines Water Works.
Diquat is a herbicide used on potato crops and aquatic weeds.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | ND | 1 | 0 | ND |
| 2019 | ND | 3 | 0 | ND |
| 2020 | ND | 1 | 0 | ND |
| 2021 | ND | 2 | 0 | ND |
| 2022 | ND | 3 | 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
NOTE: Polk City Water Supply purchases water from Des Moines Water Works which is required to test for diquat. Sample information shown below was taken by Des Moines Water Works.
| Date | Lab ID | Result |
|---|---|---|
| 2018-07-09 | OE680202 | ND |
| 2018-07-16 | OE683859 | ND |
| 2018-10-08 | OE724008 | ND |
| 2019-07-09 | OE831885 | ND |
| 2019-07-16 | OE835743 | ND |
| 2019-08-21 | OE854920 | ND |
| 2020-10-12 | OE1332018 | ND |
| 2021-07-06 | OE1748365 | ND |
| 2021-07-06 | OE1748381 | ND |
| 2022-07-05 | OE2128016 | ND |
| 2022-07-05 | OE2128018 | ND |
| 2022-09-19 | OE2175664 | ND |
| 2023-10-16 | OE2350834 | ND |