Deer Flat National Wildlife Refuge encompasses two significant areas for breeding, wintering, and migrating birds on the Pacific Flyway particularly waterfowl. The Lake Lowell sector is an irrigation reservoir that protects 10,588 acres of lake, emergent wetland, riparian forest, and sagebrush upland habitat. The water levels for Lake Lowell are raised during spring to store water and lowered in the summer and fall to provide irrigation. The Snake River Islands sector, distributed along 113 river miles from the Ada-Canyon county line in Idaho to Farewell Bend in Oregon, encompasses over 1200 acres and riparian edges on 101 islands. The islands offer important nesting and resting habitats comprised of native grass, willow, and sagebrush uplands. See for more detailed information about this site.

Ornithological Summary

Colonial waterbirds nest on both Lake Lowell and the Snake River Islands sectors of the refuge including California Gulls (~900 nests), Great blue herons, Black-crowned night herons, Double-crested cormorants, and Western and Clark?s Grebes. Exceptional numbers of waterfowl (especially Canada geese and mallards) use the refuge for breeding, as a wintering area, and as a migratory stopover. Maximum waterfowl counts in 2006-07 were 20,000 geese and 131,000 ducks. The Island sector is important breeding habitat for both geese and ducks. Shorebirds use the mudflats at Lake Lowell as a stopover during summer and fall migration. Intermountain West Shorebird Regional Plan names this as one of only 2 sites (other is American Falls Reservoir) in Idaho with greater than 5000 shorebirds in more than half years surveyed (Peak = 10,000-20,000). Some of the shorebirds present in late summer and fall include: Pectoral, Least, Baird?s, Solitary, Spotted, and Stilt Sandpipers, Marbled Godwits, and Long-billed Dowitchers. California Gulls and approximately 15 Bald Eagles winter on Lake Lowell, and two pairs of Bald eagles nest at the lake. Riparian edge provides habitat for a diversity of migratory and resident species.

Conservation Issues

Prime native forage vegetation has been lost to invasive encroachment of noxious weeds. As a result of encroachment of cheat grass, changes in fire regime on upland shrub-steppe habitat have occurred. To combat this, previously burned shrub-steppe areas have been reseeded with native bunch grasses and shrubs and ongoing treatment of noxious and invasive weeds includes mechanical, biological, and chemical controls. In addition, restoration of native vegetation and habitat is under consideration for future community projects. As feral and free roaming cat predation impacts both resident and migratory birds, a plan to trap and remove feral and free roaming cats is currently being developed.

A number of additional issues will be addressed by a Comprehensive Conservation Plan (CCP) that is currently under development. The CCP seeks to further address primary conservation problems on the refuge including recreational overuse and disturbance by watercraft, water quality issues, habitat conservation and restoration. Recreational use by motorized watercraft (including personal watercraft and water-skiers) during spring, summer, and early fall disrupts nesting and brooding of resident waterfowl, grebes, and shorebirds. Water quality of Lake Lowell is currently state listed as 303(d) for excessive nutrient pollution, extensive oxygen depletion, algal bloom, and high fecal coliform bacteria count. Fish contamination by agricultural/industrial chemicals and heavy metals affects both resident and migratory birds through trophic bioaccumulation. Elevated levels of DDE persist in soils, mudflats, and wetland areas surrounding Lake Lowell. An extensive conversion of nearby agriculture fields into residential and commercial developments has reduced refuge edge habitat. Habitat fragmentation adds additional stress to resident and migratory avian communities and other wildlife.


Plant Communities: Upland shrub-steppe consists of Sagebrush spp., Rabbitbrush spp., Four-wing saltbrush, Basin wildrye, Bluebunch wheatgrass, Idaho fescue. Non-natives include cheatgrass, Scotch thistle, Canada thistle, and Puncturevine. Riparian forests consist of Black cottonwoods, Willow spp., Hawthorn, Maple, and Ash with native hardwood shrub layers of Elderberry, Currant, and Dogwood spp. Non-natives include Salt cedar, Russian olive, Perennial pepperweed, and Indigo bush. Emergent wetlands with seasonal flood and drawdown consist of Cattail, Waterwillow, Smartweed, Sedge and Dock. Non-natives include Purple Loosestrife. Agricultural fields consist of alfalfa, corn, beans, peas, and wheat.
Topography: Gently rolling hills.
Soils: Marsing loam, Vickery Marsing silt loams, and Scism silt loams.

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