L.A. must dump water from two reservoirs

12/14/2007

By Duke Helfand,
Los Angeles Times
December 14, 2007


In the midst of a drought, Los Angeles officials announced today that 600 million gallons of water must be dumped from two reservoirs that supply a large swath of the city because an unexpected chemical reaction heightened by sunlight rendered it undrinkable.

The Department of Water and Power must drain the Silver Lake and Elysian reservoirs, which together provide drinking water to residents in portions of central Los Angeles, the Eastside and South Los Angeles.

Officials believe that intense sunlight, bromide in ground water and chlorine combined to produce bromate, a carcinogen that is dangerous through long-term exposure.

DWP General Manager H. David Nahai said the utility was acting out of an abundance of caution. He said the DWP became aware of the problem in October when an outside lab identified high levels of the compound.

The agency notified the state Department of Public Health and immediately removed the two reservoirs from service. Nahai said the DWP was notifying the public now at the direction of the state agency.

The loss of the water comes amid a prolonged dry spell that has prompted Mayor Antonio Villaraigosa to call for voluntary conservation. Nahai downplayed the impact of the water loss, saying the two reservoirs account for less than 1% of the city's annual water needs.

"At a time of water shortages, we are loath to [drain the reservoirs]," he said. "Every drop is precious. But we want to make sure that ... the public continues to retain a high level of confidence in the quality of the water."

DWP officials said they tested the city's four other open-air reservoirs and determined that the water was safe to drink.

The utility is using other water sources to replace the two reservoirs, including the Ivanhoe reservoir, which abuts the Silver Lake site but did not show the same traces of bromate.

Nahai said water from the Elysian reservoir could be used to irrigate nearby hillsides. But officials were trying to determine whether they could use the Silver Lake water, which contains the bulk of the supply at issue. If not, it will simply be dumped into the Los Angeles River and carried to the ocean.