The San Gabriel Valley Water Co. should proceed with plans to build a system to treat water destined for Hacienda Heights customers even though the chemical found in the company's wells is not as harmful to health as originally thought, state officials said last week.
The state's reevaluation of the health effect of 1,1-dichloroethylene (DCE) may permit the reopening of several water wells in the San Gabriel Valley and removes a cloud over the purity of the water being delivered in Hacienda Heights.
But Peter Rogers, who heads the state health department's sanitary engineering branch, said he still believes San Gabriel Valley Water Co. should build a treatment system to remove DCE and other volatile organic compounds from its wells. Company officials said they do not now see a reason to build the $1.3-million system, but will evaluate the state's recommendation after they receive it in writing.
Bottled Water Advised
Last September, state health officials advised the San Gabriel Valley Water Co. to notify its 5,300 customers in Hacienda Heights that they should buy bottled water because of DCE contamination. Health officials withdrew that advice a week later and said residents could safely drink the water for a limited period of time, since the main danger was that of incurring cancer through long-term consumption, and even that threat was being discounted in new evaluations by the U.S. Environmental Protection Agency.
Since then, state health officials have reevaluated the danger of DCE and disclosed last Thursday that they have reached the same conclusion as the EPA and no longer regard DCE as a likely cause of cancer.
As a result of the reassessment, the state set the recommended safety level for DCE 30 times higher than it had been, from 0.2 parts per billion to 6 parts per billion.
Gerald Black, superintendent of the San Gabriel Valley Water Co., said the most recent laboratory tests put the DCE level in Hacienda Heights water at 0.6 parts per billion and the level has never exceeded 1.3 parts per billion.
Michael Whitehead, executive vice president, said the company had planned to spend $1.3 million for an aeration system to remove DCE and other volatile organic compounds, but he does not believe that expenditure can be justified now.
But Rogers said that the wells serving Hacienda Heights are contaminated with another compound, TCE, and even though the amount of TCE is also low, these and other compounds might interact in ways that are not understood. Thus, he said, he would encourage construction of a treatment system. But Rogers added that the decision on whether to build the system is not the health department's, but rests entirely with the company.
San Gabriel Valley Water Co. is one of six San Gabriel Valley water producers with wells that are affected by the new state action level for DCE. All have wells that are contaminated with DCE in amounts that were above the old action level of 0.2 parts per billion, but are under the new level. The water producers are California-American Water Co. in Duarte, the East Pasadena Water Co., the Southern California Water Co. in Claremont, the city of Pomona and the Suburban Water System, whose affected wells are near Whittier Narrows Dam.
Some water producers have closed wells because of DCE; others have met health requirements by blending contaminated water with purer water to reduce the DCE concentration. San Gabriel Valley Water Co. could neither close wells nor blend because it had no other water source for its Hacienda Heights system.
The East Pasadena Water Co., which had one of its three wells closed because of DCE, plans to reopen it. California-American Water Co., which had one of its eight wells serving Duarte closed because of DCE, may not be able to put the well back in service despite the relaxed standard. A company officials said the well that has DCE also is contaminated with TCE and nitrates and will have to be tested again before its water is used.