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Total chromium is a naturally occurring element in groundwater supply systems that is made up of chromium 3 and chromium 6 (hexavalent chromium). Chromium is an odorless and tasteless metallic element found naturally in rocks, plants, soil, volcanic dust, humans, and animals. It is also used in several industrial processes. Total chromium is measured by summing up the concentrations of chromium 3 and chromium 6. Chromium 3 has been found to be beneficial and essential for human consumption; chromium 6 has been found to cause cancer if inhaled at high concentrations and to cause cancer in laboratory animals if ingested at high concentration levels.
The hexavalent chromium level in our groundwater supply currently meets the standard set by the United States Environmental Protection Agency MCL for total chromium (100 ppb), which includes hexavalent chromium.
For more information on quarterly hexavalent chromium sampling and public notices, please see the Hexavalent Chromium Update.
Hexavalent Chromium (CR6) Update – July 2017
Based on a decision by the Superior Court of Sacramento County, the hexavalent chromium maximum contaminant level (MCL) for drinking water, 10 parts per billion, has been invalidated. The State Water Board will not be enforcing compliance plans for hexavalent chromium, as the previously adopted MCL has been invalidated. The State Water Board does intend to develop a new MCL for hexavalent chromium. Until that time, the MCL for total chromium of 50 parts per billion remains in place. All of the City's groundwater wells, including those intermediate aquifer wells that remain connected to the water system, comply with the total chromium standard however; the City’s operations plan will not change. The City will continue to use deep aquifer wells to augment surface water supplies and limit the use of intermediate wells. For more information on the hexavalent chromium MCL please visit: State Water Resources Control Board Chromium-6 Drinking Water MCL.