Water Storage to Double at Prado Dam : Pact: In exchange for new capacity, which will reduce need for imported water, the water district must spend $1 million to help an endangered songbird.

The Orange County Water District has received permission to nearly double the amount of water it can store behind Prado Dam in exchange for spending $1 million to help an endangered songbird.

The agreement, reached Friday, was timely because the downpour over the weekend filled the Corona dam basin to its new capacity, assuring 2 million Orange County residents of an ample water supply.

“This is a huge landmark agreement,” water district spokesman James A. Van Haun said.

The accord among the U.S. Army Corps of Engineers, which owns and operates the dam, the U.S. Fish and Wildlife Service and the water district increases the amount of storable water annually from 15,000 to 29,500 acre-feet.

Under the agreement, the water district will help pay for the eradication of a weed that destroys important nesting habitats of the least Bell’s vireo, a tiny songbird on the federal and state endangered species lists.

The increase in water capacity--which amounts to more than 48 million gallons--is enough to serve about 100,000 customers for an entire year, Van Haun said. If purchased from the Metropolitan Water District, which imports water to Orange County, he said, the added water would cost about $3.2 million.

“It means in the future we won’t have to buy so much imported water,” Van Haun said, adding that the district traditionally spends $3 million to $5 million a year on water brought in from other areas. “This is free local water. We can rely more and more on our own local water supply.”

Sunday’s rain virtually assured that no new water need be purchased by the district in 1995 to serve its customers in northern and central Orange County, according to Van Haun.

“The timing couldn’t have been better for the district,” he said of the agreement, which had been discussed for the past 10 years. “We knew there were some storms on the horizon and that motivated the agency to really push to finalize the agreement.”

In exchange for the increased capacity, the water district agreed to pay the U.S. Fish and Wildlife Service to help eliminate Arundo donex, a bamboo-like weed found on about 5,000 acres of the Santa Ana River basin. Imported as an erosion-control plant in the early part of the century, Van Haun said, the weed has outgrown native plants and in the process destroyed valuable habitat areas of the least Bell’s vireo.

“It’s a big problem,” Van Haun said. “The plant replaces the habitat the bird uses for nesting.”

Biologists of the U.S. Fish and Wildlife Service could not be reached for comment on the agreement Monday.

Since early last year, Van Haun said, the water district has set aside 124 of the 2,400 acres it owns behind Prado Dam in Riverside County as protective habitat for the endangered songbird in exchange for incremental increases in the amount of water it can store. As a result, he said, the number of birds in the area has increased from 19 pairs in 1986 to 124 pairs in 1994.

“This is proof that man and wildlife can coexist,” Rep. Ken Calvert (R-Riverside) told a group of dignitaries gathered at the dam last January to celebrate an earlier, more modest increase in water capacity. “It shows that water management and environmental issues are not mutually exclusive.”

The additional water will not disturb the songbirds’ habitat, Van Haun said.