Chromium in Burbank's Groundwater
Burbank Water and Power (BWP) has been sensitive to the presence of total and hexavalent chromium in the groundwater supplies serving the City of Burbank. This sensitivity and awareness, especially hexavalent chromium issues, has been the result of ongoing monitoring of state and federal regulations as well as on a voluntary basis.
The U.S. Environmental Protection Agency (USEPA) maximum contaminant level (MCL) for total chromium is 100 parts per billion (ppb). The California Department of Public Health (CDPH) and the World Health Organization MCL are 50 ppb. The water delivered to Burbank customers during the 2009 calendar year averaged 3.8 ppb for total chromium. This data is provided annually and is located in the Water Quality Annual Report on this website. Also, Burbank publishes bi-monthly results obtained from various public buildings throughout the city on its website under ‘testing results’.
Two forms of the total chromium species may be present in drinking water supplies: trivalent chromium and hexavalent chromium. Trivalent chromium is an essential nutrient at trace concentrations; hexavalent chromium is a species of health concern. As of now there is no current MCL for hexavalent chromium and its toxicity is the basis for setting a drinking water standard which is currently being reviewed by CalEPA’s Office of Environmental Health Hazard Assessment (OEHHA). There are uncertainties in the balance of the two species in drinking water supplies and there is evidence that hexavalent chromium may be reduced to trivalent chromium in the human body, particularly in the reducing environment of saliva and gastric juices.
The water supply for Burbank comes from the Metropolitan Water District of Southern California (MWD) and a groundwater treatment facility called the Burbank Operable Unit. BWP operates the treatment facility under a permit from CDPH. The permit specifies the type of test, frequency and the method to be performed. BWP employs a state certified laboratory to perform the required and voluntary analytical testing. The laboratory sends the test results directly to CDPH and BWP at the same time. This procedure eliminates concern about possible tampering with the test results. The water produced by the treatment plant is blended with additional MWD water before it is delivered to the distribution system and is tested weekly for total chromium and hexavalent chromium among other constituents.
Chromium contamination in the San Fernando Valley water basin has been the result of industrial production over a long period of time. The Los Angeles Regional Water Quality Control Board (LARWQCB) reports have identified 205 industrial sites in Burbank, Glendale and Los Angles that could have soil contaminated with hexavalent chromium. From many sites, the soil contamination is connected with contamination of the ground water. The USEPA has been monitoring the groundwater contamination with monitoring wells located within the basin. The LARWQCB, USEPA and CDPH continue their chromium investigation. OEHHA is in the process to set a Public Health Goal (PHG) for hexavalent chromium. Currently OEHHA has published a Draft PHG of 0.06 ppb which is in review. Please see the other documents on the Draft PHG Talking Points and Burbank’s press release comment on this website for more information on PHGs.
Also, view some of the Peer Review Comments of the Draft PHG on OEEHA’s website at: http://oehha.ca.gov/water/phg/chrom092010.html