The Arid Lands Ecology Reserve, in Benton County, is one of the few large, contiguous blocks of shrub-steppe habitat in the Northwest still retaining a dominant pre-European settlement ecology and physical character. The site was closed to public access in the early 1940's, which preserved the native shrub-steppe ecosystem in a quantity and quality not found elsewhere in the Columbia Basin. Managed as a wildlife reserve and environmental research area, this site has a long history of biological and ecological studies, beginning in the 1950's. The area's diversity of habitatsfrom a windswept treeless sub-alpine ridge at 1,060 meters of elevation, to bunchgrass grassland, shrub-steppe, and riparian habitats at 130 meterssupports a wide array of unique plant and animal species. Biological inventories conducted in the 1990's yielded 20 new plant varieties and 50 species of insects previously unknown in Washington.

The Reserve supports an extraordinary assemblage of breeding birds associated with grassland and shrub-steppe ecosystems, including Ferruginous Hawk, Long-billed Curlew, Burrowing Owl, Loggerhead Shrike, Sage Thrasher, Brewer's Sparrow, Sage Sparrow, and Grasshopper Sparrow. The site supports one of Washington's largest breeding populations of Sage Sparrows (up to 200 adults), a candidate species for state listing. Breeding populations of Brewer's and Grasshopper Sparrows number as high as 300 and 1,000, respectively. Two other state candidate species, Loggerhead Shrikes and Sage Thrashers, commonly breed here; and as many as six Ferruginous Hawks, a state-listed threatened species, have been recorded during breeding season. Two year-round springs support extensive riparian areas that provide breeding habitat for flycatchers, warblers, orioles, and other neotropical migrants.

Major fires in 2000 and 2007 have disturbed large portions of the ALE. As a result, major restoration efforts are needed (and to some extent are under way) and large areas are now dominated by non-native species such as cheatgrass, knapweed, star thistle, and Russian thistle, which flourished after the fires. Fire remains a continuous threat to this landscape.