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CALFED - Cloudy Outlook for Drinking Water?

Water diverted from the Delta may not be able to meet forthcoming new national drinking water standards using currently accepted advanced treatment technologies, according to a draft study commissioned by the California Urban Water Agencies.

The study frames source water quality characteristics in the context of total organic carbon and bromide concentrations, both of which may be affected by different Delta management strategies. CUWA's Byron Buck says the study's purpose was to provide CALFED with suggested criteria related to source water to help in selecting a long-term Bay-Delta solution. Buck says the Delta presents unique challenges to drinking water suppliers due to high levels of organic carbon in runoff and to the intrusion of bromide-containing seawater. Among the primary health concerns for Delta water are pathogens, such as Giardia and Cryptosporidium, and disinfection by-products such as bromate.

One reason for the push for new standards is concern over Cryptosporidium, which is relatively harmless to healthy people but can be deadly for those with impaired immune systems. According to Bruce Macler of U.S. EPA, the agency charged with developing the new standards, Cryptosporidium is the agency's new indicator species. "It is extremely difficult to kill. If you are killing that, you can be pretty sure you are killing everything else." Ozone disinfection is required to kill Cryptosporidium; however, ozone reacts with bromide to produce bromate, a carcinogen that may also cause birth defects.

The CUWA study used "reasonable, conservative assumptions" to project what the new EPA regulations will be, says Buck. The scenario includes a limit on disinfection by-products of 40 µg per liter for total trihalomethanes, 30 µg per liter for the sum of five haloacetic acids, and 5 µg per liter of bromate. The panel evaluated the source water quality characteristics necessary to meet these requirements using standard treatment, and concluded that source water would have to contain less than 3 mg per liter of total organic carbon and less than 50 µg per liter of bromide. The report concludes that "based on the historic concentrations of these constituents [in Delta water] it is unlikely that the criteria for bromide could be met under existing conditions, even in wet years." The report goes on to call on CALFED to examinea variety of actions aimed at enhancing source water quality, including in-Delta hydraulic modifications to limit seawater intrusion, pollutant source control programs for organic carbons and pathogens, water storage and management, increased outflow and isolated facilities (the PC euphemism for new canals and water conveyances).

In the absence of better source water quality, says Buck, "water providers would have to look at microfiltration and reverse osmosis, both of which are very expensive and also cost water-perhaps increasing water demand by as much as 15% to 25%." In addition, these technologies have never been tried on the scale that would be required by agencies relying on water from the Delta.

CALFED's Rick Woodard says that it's hard to guess what the impact of the report on CALFED - whose current approach on source water is much more general - will ultimately be. Nevertheless, he says, "we are certainly very interested in knowing what the EPA's reaction is."

But Macler warns against placing too much emphasis on either the study or EPA response to it. "Water quality will be substantially improved by whatever alternative comes out of the Bay-Delta process," he says. CUWA is calling on the EPA to provide some guidance to CALFED while the new drinking water standards are in the works (a two phase process, with the first phase expected at the end of 1998 and the second in 2002). Macler notes that new regulations will be an incremental change to a system that is already very protective of human health. They will also be the result of a negotiated process that includes all stakeholders and will be at least partly based on feasibility.

"It would be disingenuous to use the study's conclusions to make an argument for a specific CALFED decision," says Macler. "My concern is that projected water quality requirements for utilities will drive decision making to the detriment of other Delta interests, such as the environment."

Contact: Byron Buck (916) 552-2929 or Bruce Macler (415)744-1884

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