Otay Water District Meets Water Quality Standards for Chromium-6 Levels

Feather River in the Sierra

Otay Water District Meets Water Quality Standards for Chromium-6 Levels

10:53 13 October in News

The Environmental Working Group (EWG) recently released a report titled Erin Brockovich Carcinogen in Tap Water of More Than 200 million Americans.

The nonprofit organization’s study analyzed chromium-6 sampling data collected by water systems throughout the U.S. between 2013 and 2015, and found that approximately 75 percent of the samples tested contained chromium-6 at levels at or above California’s Public Health Goal (PHG) of 0.02 parts per billion.

It is important to note that the State of California’s Office of Environmental Health Hazard Assessment sets the Public Health Goal for known carcinogens such as chromium-6, “At a level that not more than one person in a population of one million people drinking the water daily for 70 years would be expected to develop cancer as a result of exposure to that chemical.”

A Public Health Goal is not a boundary line between a “safe” and “dangerous” level of a chemical, and drinking water is frequently demonstrated as safe to drink even if it contains chemicals at levels exceeding their Public Health Goals. Learn more about Public Health Goals.

The Otay Water District is under the requirements of the Maximum Contaminant Levels (MCLs), which are standards set by the United States Environmental Protection Agency (EPA) for drinking water quality. An MCL is the legal threshold limit on the amount of a substance that is allowed in public water systems under the Safe Drinking Water Act. For chromium-6, the legal threshold is 10.0 parts per billion.

The Otay Water District purchases its treated water from the San Diego County Water Authority, Helix Water District, and Metropolitan Water District of Southern California. These agencies monitor for chromium-6 annually. The most recent test results from the 2015 Water Quality reports were from Non Detected (ND) to 0.04 parts per billion. Sampling results within Otay’s service area between August 2013 to May 2014 ranged from 0.04 to 0.07 parts per billion, which are more than 100 times less than MCL.

Chromium-6 is a heavy metal. It occurs naturally in California’s rock and soil and can enter the water supply through erosion. It can also leach into groundwater from industrial sites. Chromium-6 is used in textile dyes, wood preservation, leather tanning and anti-corrosion coatings.

Association of California Water Agencies Chromium-6 FAQs
State Water Resources Control Board Fact Sheet