Grays Lake Ecosystem

Fact Sheet

General:

Located on the western edge of the Greater Yellowstone Ecosystem in Bonneville and Caribou Counties, Idaho.
Includes one of the largest bulrush marshes in North America (13,000 ac)
Significant breeding area for sandhill cranes, Canada geese, Franklin's gulls, and white-faced ibis.
Marsh elevation 6386 ft.
Caribou Mountain to east highest point within watershed (9803 ft).
Ranching (cattle, sheep, hay production) predominant use of surrounding lands.

Climate:

Average annual precipitation 17 inches.
Average annual snowfall 115 inches; average accumulations of 40-50 inches.
Daytime high temperatures average 68-75° in June and July.
Hard frosts (<30°F) may occur in any month.
Record high of 103°F recorded in 1919 and record low of –45°F in 1922.

Habitat and Plant Communities:

Transitional zone between Great Basin vegetation (south) and Rocky Mountain vegetation (north).
Within approved refuge boundary, 60% palustrine emergent wetland, 20% wetland semi-wet meadow, 12% brush, grasslands, and grainfields, 5% shallow open water with submergents, and 3% aspen forest and willow thicket.
Over 170 species of grasses, sedges and forbs in wet meadows and marsh habitat, including 15 species of sedges.
3 species of exotic, invasive plants.
7 species of trees and 17 species of shrubs
No known threatened or endangered plant species.

Wildlife:

128 recorded species of breeding birds present.
Over 40 bird species nesting in the wet meadow and wetland habitats of the basin.
20 species of mammals.
4 species of amphibians.
6 species of reptiles.
2 species protected as "threatened or endangered" (peregrine falcon and trumpeter swan).
Highest breeding density of sandhill cranes in North America - an important breeding area for Rocky Mountain Population of sandhill cranes.
700-800 cranes present in May; 1000 or more cranes stage in the basin in September.
Nesting colonies of Franklin's gulls and white-faced ibis.
Site of cross-fostering study of whooping cranes in 1970s-80s. Other methods were tested, but no further efforts are currently active and no whooping cranes or whooping-sandhill crane hybrids are present.

Water:

Located within Willow Watershed, 651.45 mi² in size.
Average water depth 3.5 m in spring; <0.5 ft in late July through September.
Water sources from snowmelt and numerous springs; main inflow via Willow, Eagle, and Gravel Creeks on the east and south, and Crane Creek on the west.
Original water outlet, Grays Lake Outlet, drains to the north into Snake River via Willow Creek.
Clark's Cut, a man-made channel completed in 1924, drains into the Blackfoot Reservoir via Meadow creek.
Water discharge controlled by the Bureau of Indian Affairs for use in Fort Hall Irrigation Project since the early 1920s.
Drainage canals and drainage ditches were established during various periods (1920s, 1950s, 1960s).

Geology:

Meade Thrust Fault principle structure underlying basin.
Cretaceous rocks underlie Willow, Eagle, and Bridge Creeks, predominantly sandstones and shales.
Paleozoic and Triassic rocks underlie Gravel Creek basin, predominantly carbonates with Quaternary alluvium covering lowlands.
Tertiary volcanics (mainly olivine basalts) underlie most western drainage.
Bear Island olivine basalt.

Access and wildlife viewing:

Public road perimeter allows excellent bird viewing, particularly in May and early June when water levels are high.
Viewing opportunities from Beavertail Point (south), refuge observation area (east), and north perimeter road.
Access into marsh largely closed to the public to minimize disturbance of breeding sandhill cranes, trumpeter swans, and other waterbirds.
Small Visitors Center at refuge headquarters; no other public facilities available.
Access during fall waterfowl hunting on north half of basin.

Grays Lake National Wildlife Refuge

Established 1965 for production of migratory waterfowl and other waterbirds
Total area within proposed refuge boundary 32,825 ac.
18,330 ac within boundary controlled by refuge through fee-title, use agreements, other means.
Active research program for adaptive management of habitat and wildlife populations.
Management of grasslands and wet meadow using prescribed fire, grazing, idling, haying, and rotation systems.
3 year-round staff (manager, biologist, maintenance) and 2 seasonal maintenance staff.
Research staff for projects 6-15 seasonally.
Opportunities for interns and volunteers available for research and monitoring.

Mailing address:

     U.S. Fish and Wildlife Service
     Grays Lake National Wildlife Refuge
     74 Grays Lake Road
     Wayan, ID 83285
     Website: www.npwrc.usgs.gov/grayslk

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