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At the Tap
TAP WATER TIGHTROPE
EPA inched another few steps down the tap water treatment tightrope this year in an effort to negotiate some kind of balance between two different health risks - those from disease-causing microbes and those from carcinogenic by-products of the disinfection process used to kill them. Three new draft drinking water rules have been added to the books since last year. The first, called the Information Collection Rule, requires larger water utilities to test source waters before, during and after treatment for both microbes and disinfection by-products. The second, the Disinfectant By-Products Rule, sets interim numerical standards for a variety of disinfection chemicals and their by- products. The third, the Enhanced Surface Water Treatment Rule, "makes sure no one backs off microbe treatment to comply with the new disinfection by-product standards," says EPA's Bruce Macler. Data rolling in as a result of the first rule will help in the development, review and implementation of the other two, says Macler.
EPA has also been tackling arsenic - a drinking water contaminant that occurs in so many places naturally that its regulation might require treatment of almost every groundwater source in the country. Intense discussion on the arsenic issue is now centering on whether the 50 ppb EPA currently allows should be reduced to somewhere in the range of 2-20 ppb. If the new standard falls at the 2 ppb end, it could present problems for water suppliers drawing on the Delta, where ambient arsenic levels have been measured at 5 ppb. Contact: Bruce Macler (415)744-1884 4/93
BURREC PUSHES PLANNING
Twenty out of the more than one hundred water districts served by BurRec's Central Valley Water Project have water conservation plans that meet the agency's strict new evaluation criteria. BurRec published the new criteria in April last year, as required by the 1992 CVPIA - also known as the Miller-Bradley bill. By April 1994, BurRec had used the criteria to evaluate around 120 district water conservation plans, 95 of which had been updated to meet the new criteria, but only 22 of which met them. The other 73 are still being evaluated or revised.
BurRec's Debra Goodman says districts must show what conservation BMPs they plan to employ, and how and when they will be implemented. Without adequate plans, their CVP water contracts may not be renewed. To help districts improve their plans, BurRec is offering technical assistance through the state Department of Water Resources and will have two new water conservation specialists in the field by early next year.
Goodman couldn't say how much water has been saved yet as a result of the planning effort. But the new criteria do require districts to measure water inputs and outputs, something many will be doing for the first time, and then to provide BurRec with an annual progress report. Some figures may be forthcoming soon; some are already being plugged into a new conservation data base.
Goodman says the two next big steps are a 1996 update of the CVP users criteria and the early 1995 release of the BurRec's new "WestWide" conservation criteria for all 17 western states. Both will be available for public comment. Contact: Debra Goodman (916)978-5313 6/93
FROM TOILET TO TAP?
We'd all like to think our drinking water burbles up from a pristine mountain spring before pouring out pure and clear from our faucets. Yet in reality, water is used, treated, then used again - a fact the San Diego County Water Authority hopes it can teach its customers so an innovative water reuse project can get underway. The Water Authority's Patricia Tennyson says the agency wants to treat reclaimed water to create a new potable water supply. The plan is to send effluent through a water reclamation plant for tertiary treatment, then to an advanced water treatment facility for repurification using microfiltration, reverse osmosis, nitrate removal and other treatment processes. This water would be conveyed to a reservoir to mix with local runoff and imported water supplies. The blended water would then undergo conventional drinking water treatment before being piped to consumers.
Tennyson says the repurified water can meet or exceed the quality of the raw water supply now in the city's reservoirs. "We've gone to great lengths to ensure the safety of this potential water source," she says. "Our biggest hurdle is overcoming the public's perception that the water is unsafe."
Although San Diego relies on imported water for 90% of its supply, surveys showed that only 20% of its residents understood their water had been used before. "Once people realize how the water supply process works and understand this new technology, they agree that we can make the water clean," Tennyson says. One other hurdle may be treated water's cost - an estimated $924 an acre- foot. But Tennyson says this amount is comparable to or cheaper than the cost of developing other water supplies such as a desalination plant. The state's Department of Health Services has given its conditional approval to the project, vastly increasing the potential uses for reclaimed water statewide. "Regardless of whether we end up doing this project, it shows us that any city in California could use repurified water for drinking," says Tennyson. Contact: Patricia Tennyson (619)692-9356
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