Officials Downplay Chemical Found in Simi Valley Water

State regulators on Friday reassured residents of central Simi Valley there was no health risk from the trace amounts of perchlorate found in well water blended with their drinking water.

Southern California Water Co., which serves 13,000 homes and businesses, about 40% of Simi Valley, said this week that since last August, it has detected minute levels of the contaminant, which has been linked to thyroid damage.

The chemical is used in road flares, fertilizer and as a rocket propellant.

Although Simi Valley is downhill from Rocketdyne’s Santa Susana Field Lab, a Boeing Co. official reiterated the company’s position that there was no evidence that perchlorate had traveled beyond Boeing property.

“The good news -- if there is any -- is that some labs have the ability to test very low levels of perchlorate, but there is no health risk at those low levels,” said Tacey Derenzy, a spokeswoman for the California Department of Health Services.

In testing its two groundwater wells in Simi Valley, Southern California Water detected perchlorate at levels ranging from 1 to 3.5 parts per billion.

One ppb is roughly equal to a single drop in an Olympic-size swimming pool.

The state is still developing standards for the contaminant but has a goal of having no more than six ppb. That’s the level at which a water provider is required to notify its customers of the presence of perchlorate.

Dawn White, water quality manager for Southern California Water, said that the company has agreed to notify members of the Santa Susana Field Laboratory Working Group of the results of its quarterly well water tests.

About 10% of the water the company delivers in Simi Valley comes from the two wells, White said.

She said the company blends about 3.5 gallons of uncontaminated water from the Metropolitan Water District with each gallon of well water it pumps. The result is water with much less than 1 ppb of perchlorate.

“We’re doing regular monitoring, and the water is meeting all drinking-water standards,” White said.

“If the [perchlorate] level should go up, we’ll take appropriate action,” White said.

That would include adjusting blending ratios, further treating the water or no longer using water from those wells.