State Water Board Approves Removal of Drinking Water Standard for Hexavalent Chromium

Aug. 2, 2017

Action Fulfills Court Order; Board to Create New Standard

In accordance with a recent court ruling, the State Water Resources Control Board adopted a resolution today to remove the current maximum contaminant level (MCL) for the pollutant hexavalent chromium found in drinking water. The State Water Board will now begin work on establishing a new MCL for the contaminant.

On May 31 the Superior Court of Sacramento County invalidated the MCL for hexavalent chromium, saying the state “failed to properly consider the economic feasibility of complying with the MCL.” The court did “not decide whether the MCL is economically feasible,” nor did it conclude whether the MCL was too high or too low. Rather, the court said the regulation did not adequately document why the MCL was economically feasible.

Hexavalent chromium, also known as chrome 6, is a naturally occurring heavy metal that is also used in a variety of industrial processes. Long-term exposure to the metal may cause cancer.

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California became the first state in the nation to issue a drinking water standard for chrome 6 when it set the MCL at 10 parts per billion (ppb) in 2014. The regulation was crafted when the Division of Drinking Water was under the authority of the California Department of Public Health. The Division was transferred to the State Water Board in July 2014.

While the Board disagrees with the court’s decision, it has decided not to appeal and instead will begin the process for adopting a new MCL as soon as possible. The Board will use the wealth of data collected over the last three years since the standard was adopted to help craft a new MCL. Generally, regulation development takes between 18 and 24 months to complete.

With adoption of the resolution, staff will now begin the process of having the text of the current MCL deleted from the California Code of Regulations. The State Water Board must let the court know this has been done by Aug. 15. After the Office of Administrative Law approves the proposal to remove the text, it will be effective in late September.

Since the current MCL will be removed, the State Water Board will no longer enforce compliance plans that public water systems entered into for hexavalent chromium.

However, the state MCL for total chromium of 50 ppb will remain in place. Total chromium measures both trivalent and hexavalent chromium in water together and does not indicate how much of either type exists. Trivalent chromium is not considered toxic and is an essential nutrient in trace amounts. The U.S. Environmental Protection Agency’s MCL for total chromium is 100 ppb.

Chrome 6 remains a threat to public health as it is still present in the water supply of many public water systems. Because of this, the Board will establish a new MCL for Chrome 6 as close as possible to the public health goal set by the Office of Environmental Health Hazard Assessment. The new standard could be at the same level as the now invalid one.

Public water systems that planned and, in some cases, completed projects to install treatment may be able to use that information and experience in any work necessary to comply with the new MCL when it is adopted. Public water systems that have already installed and are operating treatment systems are encouraged to continue to operate these facilities.

For more information on the development of the new drinking water standard for chrome 6, see the Division of Drinking Water webpage.