Walker Lake lies at the terminus of the Walker River in Western Nevada. The Walker River is one of three major rivers that drain the east side of the Sierra-Nevada Mountains, and it supports riparian, wetland, riverine, and at its terminus, a desert lake ecosystem. Walker Lake itself is a remnant of ancient Lake Lahontan which covered much of central and northern Nevada during the last Ice Age.
Situated in the Basin and Range Province, Walker Lake is bounded to the east and west by arid, jagged, sparsely vegetated, and steep ranges. Mt. Grant, on the west side of the lake, crowns the Wassuk Range at 11,245 feet. The lake itself supports an extremely limited riparian/wetland community, mostly restricted in extent to the southern end of the lake. Much of the lakes perimeter is either unvegetated, or supports lowland desert shrub and shrub-steppe communities. A few springs and small tributaries enter the lake from the Wassuk Range.
Immediately north of the lake, the Walker River meanders extensively across the valley floor prior to entering the north end of Walker Lake. This section of the river is essentially a delta, and it supports an expanse of salt cedar, though historically this area was likely a cottonwood-willow riparian complex. This area, from the border of the Walker River Indian Reservation to the lake, is not included within the boundaries of the IBA. Should restoration efforts in this area be initiated and meet with success, expansion of the IBA boundary to include the Walker River delta may be warranted.
Walker Lake is nominated as an Important Bird Area on the basis of its populations of endangered, threatened, or vulnerable species and because the area supports more than 10,000 water birds. As one of only five remaining endorheic (terminal freshwater) lakes in the world, Walker Lake provides habitat to Western Snowy Plover, Common Loon, Western, Clarks, and Eared Grebes, Double-crested Cormorant, White-faced Ibis, Tundra Swan, Snow Goose, Gadwall, Redhead, Ruddy Duck, Northern Shoveler, and American White Pelican. About 1,400 Common Loons assemble on Walker Lake each fall, constituting the largest known inland congregation west of the Mississippi River. Recent radio tracking of a few of these individuals indicates that their breeding grounds are centered in west-central Saskatchewan; their wintering grounds remain unidentified. The Walker Lake loons are also heavily contaminated with mercury. Walker Lake itself is heavily contaminated by mercury as a result of historic mining activity in the Walker River watershed. This mercury may be the source of the metal accumulating in the loons, but the mercury in these birds tissues may also originate in their wintering grounds.
The Walker River, the primary source of water for Walker Lake, provides over 90 percent of its inflow, and is itself a significant riparian and wetland habitat for birds. The terminal delta of the Walker River supports extensive riparian vegetation, although it likely much degraded from its original condition. Vegetation in this area is primarily willow and tamarisk, with a few large cottonwoods. PIF species of concern reported in this area include Swainsons Hawk, Prairie Falcon, Gray Flycatcher, Sage Thrasher, Loggerhead Shrike, White-faced Ibis, Orange-crowned warbler, and Wilsons Warbler. A single Yellow-billed Cuckoo was recorded migrating through the area during a Breeding Bird Atlas survey. Restoration of the overstory of the area could encourage more use of the area by this species.
This system is on the brink of collapse because of over-appropriated water. Dissolved solids in the lake are about to exceed level where fish can reproduce. Food chain will collapse in the absence of fish and the piscivorous birds will likewise disappear. Groundwater is pumped upstream for farm irrigation; probably affects system hydrology. Drought, combined with over-appropriation of water, further impacts lake water levels and dissolved solids. Invasive grasses adjacent to lake, larger problem is salt cedar (tamarisk) on the Walker River. Each plant can use up to 200 gal. water/day, thus robbing the lake of potential inflows.
Intermittent research on the migration habits of the Common Loons as well as mercury loading in the species has been conducted by Boise State University. Funding is the limiting factor, though time is pressing as the ecosystem nears collapse.
Wetlands associated with seeps and springs on south end of lake are also a minor component of this type.
Walker River, the only significant tributary, is ~%150 parceled out for water and only reaches the lake in good water years.