Testimony by David Spath
Before Senate Committee on Environment and Public Works
Concerning MTBE in Water
December 9, 1997

My name is David Spath. I am the Chief of the Division of Drinking Water and Environmental Management with the Department of Health Services. The Department is responsible for regulating public water systems in California.

I appreciate the opportunity to come before you and discuss the Department's efforts in determining the extent of MTBE contamination of drinking water sources as well as our work toward establishing primary and secondary drinking water standards for the chemical.

The first finding of MTBE in a drinking water source in California occurred in 1990. MTBE was detected in Lobos Creek, which was used by the Presidio of San Francisco as a drinking water source. The chemical was also found in two shallow test wells being developed by the Presidio. These wells were never completed. The source of the MTBE was concluded to be surface runoff from surrounding residential and commercial areas. As a result of these findings. the Department established a 35 parts per billion (ppb) drinking water

Action Level for MTBE.

In February 1996, after information in the scientific literature suggested that MTBE may be a potentially significant threat to contaminate groundwater, particularly from leaking underground storage tanks. the Department issued an alert to public water systems recommending that they undertake voluntary monitoring of MTBE in their sources. We also notified public water systems of our intent to adopt a regulation identifying MTBE as an unregulated chemical for which monitoring would be required.

On February 13, 1997, the Department adopted an unregulated chemical monitoring regulation for MTBE. The regulation affects more than 4,400 water systems and approximately 11,000 drinking water sources that include both surface water and groundwater. To date, 479 water systems have reported monitoring results to us. The number of sources sampled is 2,442. The results indicate that 17 systems have detected MTBE in a total of 27 sources. Of those 27 sources, 15 are groundwater sources and 12 are surface water sources. Two water systems have reported sources with levels above the State Action Level of 35 ppb. They include the City of Santa Monica and California Water Service Company in Marysville. In each case the source of water was groundwater. All of the monitoring results that I have cited are available to the public through our Internet site (http://www.dhs.cahwnet.gov/prevsrv/ddwem/index.htm) and are undated monthly.

In addition to overseeing these monitoring activities, the Department is in the process of implementing recently adopted State labs (Senate Bill 1189 (Hayden) and Assembly Bill 592 (Kuehl)), which require the Department to adopt primary and secondary drinking water standards for MTBE. Adoption of the secondary standard is required by July 1998, while the primary standard is required to be adopted by July 1999.

Secondary standards are intended to present aesthetic degradation of drinking water. In the case of MTBE. the focus is on the potential taste and odor problems that the chemical can cause. Unlike federal secondary standards which are only advisory, California law mandates that the Department enforce State secondary standards. Therefore, public water systems will be required to comply with the MTBE secondary standard.

The secondary standard for MTBE will be based on data from experiments that have been performed by researchers, using panels of subjects who were exposed to varying concentrations of MTBE in water to determine the levels at which it could be smelled or tasted. Recent studies indicated that MTBE exhibits an odor that could be sensed by some panelists at concentrations ranging as low as 2.5 ppb to 21 ppb. These studies also indicated that panelists could taste MTBE at levels ranging from 2 ppb to 40 ppb. The Department has drafted a proposed regulation which would establish a secondary standard for MTBE at 5 ppb. The draft regulation is undergoing administrative review. We expect to have the proposed regulation available for public comment in early 1998.

With regard to the primary drinking water standard, as I previously indicated, the Department currently uses an Action Level for MTBE of 35 ppb in drinking water to protect against adverse health effects. This level is based on non-carcinogenic effects of MTBE in laboratory animals, with a large uncertainty factor that provides an added margin of safety for drinking water. Although animal studies suggest that MTBE may be a weak carcinogen when inhaled, it is not clear if MTBE has similar effects when ingested. This issue is still being studied.

However, even if MTBE is determined to be a weak carcinogen through all routes of exposure, the secondary standard of 5 ppb that the Department is proposing should be sufficient to provide an adequate margin of protection from any potential health concerns.

Along with a strong drinking water regulatory program, the Department also recognizes the need to protect sources of drinking water. Pursuant to the 1996 federal Safe Drinking Water Act Amendments and recently enacted State law (Senate Bill 1307 (Costa)), the Department, in coordination with federal, state, and local agencies, is developing a Drinking Water Source Assessment and Protection Program that is designed to assess the vulnerability of drinking water sources to contamination from chemicals such as MTBE and to develop strategies to protect these sources from future contamination. Depending on the states ability to match federal funding for this program, the Department expects to complete the program plan and submit it to the U.S. Environmental Protection Agency for review and approval by mid-1998. Once the program is initiated we anticipate that, as envisioned by the federal and State laws, local partnerships between water systems, local government, private industry and the public will be developed to implement voluntary drinking water source water protection measures that will support existing state and federal source water protection activities.

That concludes my presentation. Thank you again for the opportunity to present our testimony on this important issue.