Chemical Find Shuts Down Two LA Water Reservoirs

Via physorg.com -

(AP) -- Two reservoirs that supply drinking water to parts of the nation's second-largest city have been shut down and will be drained because a rare sunlight-fueled chemical reaction tainted them with a cancer-causing chemical, utility officials said Friday.

The Los Angeles Department of Water and Power plans to drain 600 million gallons from the open-air reservoirs early next year, a process that will leave them out of action for three to four months amid drought conditions, department spokesman Joseph Ramallo said in a statement. The two reservoirs supply only about one-third of 1 percent of the city's annual water consumption, or about the amount the entire city consumes in a day, Ramallo said. The closures haven't left the city short of water because demand decreases in the fall and winter, he said.

The chemical, bromate, is dangerous only after long-term consumption, officials stressed.

"There is no immediate health risk," Ramallo's statement said.

...

With the discovery surfacing during a drought, city officials said they would try to use some of the water for irrigation and other uses that don't involve human consumption. The rest will be dumped into the Los Angeles River, which drains into the Pacific Ocean.

The bromate formed when the reservoir water, combined with groundwater, was treated with chlorine and exposed to sunlight, Ramallo said, adding it was "the first time an occurrence like this has ever been observed."