Little Bird, Big Success : Plan to Supply More Water to Orange County Also Protects Endangered Bell’s Vireo

At first glance, the Prado Dam seems to have little connection with birds.

Stretching behind the 566-foot-tall structure fronting the Riverside Freeway is a broad basin--dry and brown this time of year--that helps supply much of the water for about 2 million Orange County residents.

About a mile away lies a 124-acre forest of willow trees gently swaying in the breeze.

It is to this peaceful patch of forest near the border of Orange and Riverside counties that the least Bell’s vireo--a tiny songbird listed as endangered by federal and state officials--is expected to return to nest in March, after wintering in Baja California.

And it was atop this dam on the Santa Ana River that various county, state and federal officials gathered this week to dedicate an agreement deemed by many as a triumph for bird and humankind.

“This is wonderful,” said Philip L. Anthony, president of the Orange County Water District, which provides water for much of Orange County. “It’s one of the biggest and best water conservation projects in years.”

The agreement signed Tuesday is between the water district--which owns 2,400 acres behind Prado Dam--and the Army Corps of Engineers, which manages the facility. Its purpose: to significantly boost the amount of water available to Orange County residents in exchange for a preserve that could help save the songbird.

“This is proof that man and wildlife can coexist,” Rep. Ken Calvert (R-Riverside) told the dignitaries. “It shows that water management and environmental issues are not mutually exclusive.”

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The agreement marked the culmination of years of negotiations between the two government agencies. Built in 1941 primarily to control flooding, the dam has for many generations also caught enough rainwater to supply about 75% of the water consumed by residents of north and central Orange County. The rest of their water, district officials say, generally comes from either the Colorado River or Northern California.

In recent years, political and environmental concerns have put the future of such imported water in doubt. About six years ago, water district officials began negotiating with the corps for permission to increase the amount of water the county could store in the Prado Basin.

A 1986 environmental impact statement indicated that use of the basin had seriously jeopardized the existence of the least Bell’s vireo, a four-inch-high songbird that nests in the lower branches of the area’s willow trees.

In exchange for its permission to increase the amount of stored water, the corps--working with the U.S. Fish and Wildlife Service--asked the Orange County Water District to set aside acreage as a natural songbird habitat.

Since the mid-1980s, the district has spent about $1.5 million to plant thousands of willow trees on 124 acres at the far end of the basin and to trap cowbirds, which prey on the vireo’s young, said James A. Van Haun, executive assistant to the general manager.

As a result, he said, the number of known songbirds has increased from 19 nesting pairs in 1986 to 123 last year. Eventually, Van Haun said, the district plans on setting aside 300 acres as vireo habitat.

Under the new agreement, the level of rainwater allowed to be stored in the basin from March 1 to Sept. 1 will increase to 498 feet above sea level--enough extra water to meet the needs of about 120,000 people a year.

Historically, Van Haun said, the Army corps did not allow the water to exceed 494 feet above sea level, although that rule was waived on several occasions in recent years because of emergencies. Eventually, he said, the water district hopes to raise the maximum allowable level to 505 feet, an increase of about 29,000 acre-feet, or enough to serve 150,000 people a year. One acre foot is 326,000 gallons.

“We’re talking about a lot of water,” Van Haun said.

“Water is the lifeblood of California,” Packard, one of the signers, said. “Without water we would live in a desert. This is a great water conservation project.”

Water for the Birds

In exchange for more water storage behind Prado Dam, the Orange County Water District has paid the Army Corps of Engineers $1 million and set aside 124 acres as habitat for the least Bell’s vireo. A look at the endangered songbird that nests in willows in the flood plain behind the dam.

Least Bell’s vireo: Vireo bellii pusillus . Status: State and federal endangered species. Habitat: Creeks and rivers, mainly found at Prado Dam and Camp Pendleton Marine Corps base. Diet: Mostly insects. Population: About 300 pairs. Brood: Three to five eggs in nests usually suspended from branches. Dangers: Besides rapidly losing habitat, the elusive vireo is a victim of brood parasitism by cowbirds. Cowbirds lay their eggs in the vireo’s nest, and cowbird chicks often displace the smaller vireos.

Source: Audubon Society Field Guide to North American Birds; Researched by CAROLINE LEMKE / Los Angeles Times