Born in the Sierra, Walker Lake, Nev., is the terminus for the Walker River watershed - a watery gem amid arid land. It supports threatened fish and hundreds of thousands of breeding and migrating water birds, including spring and fall visits from common loons.

Walker Lake's existence spans millions of years. Along with Pyramid Lake in northwest Nevada and Mono Lake in eastern California, Walker is a remnant of the Pleistocene Lake Lahontan, which covered much of central and northern Nevada during the last Ice Age. As the climate dried, Lake Lahontan receded and many closed valleys became isolated dry lake beds. The Walker River is one of three major rivers in Nevada draining the east slopes of the Sierra, supporting riparian, wetland and desert lake ecosystems.

Native Americans inhabited the Walker River Basin dating back more than 11,000 years. A hunter-gatherer society, the native families traveled in small groups relying upon pine nuts, game and Lahontan cutthroat trout.

At that time, flows to Walker Lake are estimated at 250,000 to 300,000 acre-feet of water per year (an acre-foot is approximately 326,000 gallons of water, enough to cover a football field in a foot of water). Flows to Walker Lake have averaged less than 90,000 acre-feet a year since the 1930s.

In 1859, the Nevada mining boom brought settlers to the Walker River Basin. By 1890, the first diversion ditch on the Walker River was constructed. In 1919, the state formed an irrigation district and within the next five years, two reservoirs were built to store and distribute Walker River water, irrigating 93,600 acres of land. The dams and reservoirs effectively ended spawning runs for native Lahontan cutthroat trout.

While less water flowed into the lake, total dissolved solids increased four-fold, creating a lethal stew for zooplankton and fish. In the 1950s, Walker Lake was one of only a few fisheries in the state for the introduced species of Sacramento perch and popular with anglers. By the 1960s, these fish reached their tolerance level for dissolved salts and died out along with commercially fished carp. The dramatic change in lake level has extripated Walker Lake's native Tahoe sucker that has not been seen at the lake since the mid-1990s.

The lake was valued as a popular stocked fishery, but its ecosystem continues to be threatened by rising salt levels and declining lake levels. Trout stocking was discontinued in 2008, and increased alkalinity decreases the size and age of surviving fish.

If the fishery at Walker Lake is lost, an important bird habitat also will be lost as the American white pelican and migrating common loons depend on Walker Lake - both are listed by the U.S. Fish and Wildlife Service as sensitive species. Other rare birds relying on the lake's ecosystem are snowy plovers, long-billed curlews, double crested cormorants and white-faced ibis.