Chromium (total)
South Grayson Special Utility District
Chromium is a naturally occurring metal, but industrial uses can elevate its levels in water. One form, hexavalent chromium, causes cancer. Total chromium is not a good indicator of the amount of hexavalent chromium in drinking water.
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 | 6.27 ppb | 3 | 3 | 4.70 ppb - 8.00 ppb |
| 2020 | 12.0 ppb | 1 | 1 | 12.0 ppb |
| 2021 | 5.20 ppb | 1 | 1 | 5.20 ppb |
| 2022 | 0.767 ppb | 3 | 2 | ND - 1.20 ppb |
| 2023 | 2.00 ppb | 1 | 1 | 2.00 ppb |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
EPA Maximum Contaminant
Level (MCL): 100 ppb
The legal limit for total chromium, established in 1991, was based on a 1958 toxicity study in laboratory animals, and applies to both the less-toxic trivalent chromium and the more-toxic hexavalent chromium forms of this compound. This limit does not protect against the risk of cancer from ingestion of hexavalent chromium.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-10-15 | Q1840862015 | ND |
| 2019-08-13 | Q1954236001 | 4.70 ppb |
| 2019-08-13 | Q1954236002 | 6.10 ppb |
| 2019-08-13 | Q1954236020 | 8.00 ppb |
| 2020-08-06 | Q2031194019 | 12.0 ppb |
| 2021-11-10 | Q2131631005 | 5.20 ppb |
| 2022-02-08 | Q2204251001 | 1.10 ppb |
| 2022-04-26 | Q2212466001 | 1.20 ppb |
| 2022-04-26 | Q2212466002 | ND |
| 2023-05-16 | Q2318439017 | 2.00 ppb |