The Columbia River Basin

Bibi Booth and Shelly Fischman

Geology and Climate

The Columbia River drops more than 735 m from its headwaters in British Columbia, winding over 1,950 km to the Pacific Ocean. Although the river itself flows from Canada through only two states, forming part of the Washington-Oregon border, the vast Interior Columbia River Basin is defined by the area drained by the river and its many tributaries. This 58-million-hectare area (about the size of France) extends roughly from the crest of the Cascade Mountains of Oregon and Washington east through Idaho to the Continental Divide in the Rocky Mountains of Montana and Wyoming, and from the headwaters of the Columbia River in Canada to the high desert of northern Nevada and northwestern Utah.

The Rain Shadow Effect

Shelly Fischman/Bibi Booth

The Columbia River Basin is a complex tapestry of mountains, high plateaus, desert basins, river valleys, rolling uplands, and deep gorges woven together by the Columbia River and its tributaries.

Mountains are a major and dramatic presence in the Columbia River Basin. There are a number of mountain ranges in the basin, including the volcanic Cascades forming the western border and the Rocky Mountains on the basin's eastern border.

South and east of the Cascades are the Klamath Uplands, which support lodgepole pine and juniper forests. The Columbia Plateau ecosystem, an old basaltic lava field, consists of a variety of grasses and shrubs. The remote Owyhee Uplands include mountains and a rolling plateau transected by deep canyons and covered by sagebrush, bunchgrasses, and junipers. The upper Snake River floodplain supports cottonwoods and grasses. Irrigated croplands dominate many valleys, plateaus, and uplands. The northern reaches of the arid Great Basin ecosystem consist of sagebrush, bitterbrush, and rabbitbrush at lower elevations.

Larry Ridenhour, BLM

The largest tributary of the Columbia River is the Snake River, flowing from its headwaters in Yellowstone National Park for over 1,670 km through Idaho, Oregon, and Washington. Here, on the Oregon and Idaho border, the Snake River carved the 2370 m Hell's Canyon, the deepest gorge in North America

Much of the basin experiences the rain shadow effect of the north-south mountain ranges that block moist winds from the Pacific Ocean. As the air rises, it cools, losing ability to retain moisture. Rain and snow fall on the western side, while lands east of the mountains remain arid. Rain shadows are particularly evident where major mountain ranges are perpendicular to the direction of prevailing winds and storm tracks coming from the ocean, as with the Cascades. One of the most dramatic climate changes occurs here where the lush, moist old-growth forests on the western side give way to an arid shrub-steppe environment on the eastern side. Climate varies greatly throughout the basin, depending upon elevations ranging from just above sea level to over 3,900 m. Annual precipitation can vary from about 25 cm to 250 cm.

National Park Service

A common feature of the Columbia River Basin is the shrub-steppe ecosystem where moisture is scarce (coming mostly from snow in winter), the wind is persistent, and temperatures vary from 38C in summer to well below freezing in winter.

Big sagebrush is especially adapted to survive these conditions. Its root structure can reach as far as 27 m in diameter, dominating the water source and limiting the number of other large plants that can establish themselves. Its small gray-green leaves are covered with minute white hairs that keep water in the plant. In this harsh climate, sagebrush provides important cover and forage for wildlife.

Accompanying sagebrush in the community are a variety of native plants such as rabbitbrush, bitterbrush, greasewood, winterfat, spiny hopsage, horsebrush, fescue, Indian ricegrass, bluebunch wheatgrass, and wildrye. Other herbaceous plants, or forbs, include lupines, globe mallow, Indian paintbrush, sego lilies, phlox, and arrowleaf balsamroot. An occasional prickly pear cactus can also be found.

Fish and Wildlife

The Columbia Basin's deserts, forests, rivers, and rangelands provide integral habitat for 609 known fish and wildlife species, including some of the most rare and endangered species in North America: bull trout and sockeye salmon in the rivers of Oregon, Washington, and Idaho; bald eagles and vesper sparrows throughout the basin; gray wolves, grizzly bears, and even the elusive Canada lynx in remote areas of Idaho and northwestern Montana.

Forbes such as arrowleaf balsamroot are part of the sagebrush community.


Larry Ridenhour, BLM

Close to 3,800 invertebrate species have been identified in the basin, but an estimated 20,000 more-including various species of ants, spiders, and butterflies-are yet to be described. Millions of migratory birds rest and feed in various wetlands and forests within the basin. The Snake River Birds of Prey area near Boise, Idaho, harbors the densest nesting concentration of birds of prey in North America, including more than 800 pairs of eagles, falcons, hawks, owls, and other raptors.

Don Smurthwaite, BLM
Sagebrush-steppe habitat in southwest Idaho at the foothills of the Owyhee Mountains. Wildlife use the sagebrush community at different times of the year for different purposes. Sage grouse eat sagebrush leaves in the winter. Golden eagles actively hunt the black-tailed jack rabbit. Mule deer use the shrubs to hide from predators and rear their young

Oasis in the Desert

One of the premier birdwatching sites in the United States is found in an unlikely spot-the remote high desert of Harney Basin in southeastern Oregon. Here, snowpack from the Steens Mountains drains into a complex system of landlocked lakes, marshes, and waterways at the Malheur National Wildlife Refuge. These wetlands attract thousands of migratory birds each year, representing over 300 species.


Barry Rose, BLM
Another plant suited to the sagebrush community is Indian paintbrush. A semi-parasitic plant, its roots penetrate the roots of other plants, such as sagebrush, to steal nutrients.

Another unlikely haven for wildlife is the Hanford Reach in eastern Washington. Here, on the last free-flowing stretch of the Columbia River, elk, salmon, and a variety of other wildlife find refuge in the noncontaminated buffer zones of a closed plutonium factory that has left massive radioactive wastes in some areas. A stretch of the river is proposed for wild and scenic designation, and parts of the area are under consideration for addition to the national wildlife refuge system.


Muskrats, and people, are naturally attracted to water.

.A. Lynn Burton, USFS

Anadromous Fish

Few things link the Columbia Basin like anadromous fish. These fish reproduce and rear in fresh water, then migrate downriver to the ocean. As adults, they return to the streams and rivers where they hatched to start the cycle over again. Some anadromous fish travel over 1,440 km on this journey, returning to the exact location where they hatched.


The varied wildlife and good fishing attract people to the Columbia River Basin.

A. Lynn Burton, USFS

Within the basin, there are six species and subspecies of fish whose habitats span from the waters of the Pacific Ocean to the mountains of the Continental Divide bordering Idaho and Montana. These are fall, spring, and summer chinook salmon; sockeye and coho salmon; and steelhead trout. Salmon are considered keystone species, supporting all others in the basin. Salmon contribute nutrients to streams that, in turn, support other aquatic and terrestrial species. Without salmon, the ecosystem "unravels."

For example, in Idaho's Redfish Lake, named for the red sockeye salmon that provided color to the lake during spawning season-sockeye salmon seldom return to spawn and die. Much-needed algae and zooplankton formerly generated by decomposing salmon carcasses are gone from the lake, limiting the food source for young sockeye. This lack of nutrients also affects bull trout, Westslope cutthroat trout, sculpins, suckers, clams, and mussels. On the banks, river otters have to find other food sources, as do bears and eagles. Birds of prey, especially osprey, have been moving away from streams and rivers to find food.

The wetlands of Malheur National Wildlife Refuge in arid southeastern Oregon make this a favorite stopover and feeding site for birds.


Beth Ullenberg, USFWS

For thousands of years, salmon have played an important cultural role for the people in the Columbia River Basin, not only as a keystone species and food source, but also because of their awe-inspiring life cycle. As a result, restoring historic salmon runs has been a driving force behind many recent management initiatives in the basin.

Management Challenges

Just as salmon cross jurisdictional boundaries, so do many of the issues faced by land managers in the basin. The spread of weeds, wildland fires, disease spores, stream silt, and air pollution, as well as the loss of migratory bird habitat, all clearly cross land-ownership boundaries.

To ensure these issues are adequately addressed, federal agencies are working together to develop a scientifically sound ecosystem-based strategy for managing 28 million hectares of public lands in the Interior Columbia River Basin. This far-reaching effort, the Interior Columbia Basin Ecosystem Management Project, seeks to restore and maintain healthy ecosystems and support the economic, social, and cultural needs of people and communities.

Magnificent bighorn sheep can be seen in the Hell's Canyon area.

A. Lynn Burton, USFS

The project's first step was to conduct an unprecedented study of the entire area. The result was The Integrated Scientific Assessment for Ecosystem Management in the Interior Columbia Basin and Portions of the Klamath and Great Basins, published in September 1996. This comprehensive scientific analysis involved scientists and technicians from federal and state agencies, universities, and private contractors who examined changing conditions in the basin over the last 100 years. They confirmed that the Columbia River Basin has undergone dramatic ecological changes as the region has been settled and developed.

Changing Landscapes

A hundred years ago, the basin featured large, widely spaced, sun-loving trees. Frequent, light fires cleared competing vegetation. Plant and animal species migrated freely through large blocks of habitat. Over the last century, harvesting of large old-growth trees resulted in forests with smaller, densely grown, shade-tolerant trees. As trees became crowded, increased competition for water and nutrients made them susceptible to damage from insects and diseases. In addition, historic suppression of fire allowed shade-tolerant species to fill the understory. This provided a fuel ladder to the taller trees, increasing the likelihood that wildland fires would be severe and costly.

The Bureau of Land Management (BLM) and the U.S. Forest Service are now using prescribed (carefully managed) burning to reintroduce fire into the ecosystem in order to avoid catastrophic wildland fires. They also are experimenting with ways to use forest thinning and various timber harvest techniques to reduce fuel loads.

Wildland fires also historically cleared organic debris from the rangelands, killed nonsprouting species such as sagebrush, and stimulated regrowth of sprouting shrubs and grasses. However, roads and agricultural lands stopped the spread of fire, and people suppressed fires whenever they could. As a result, fire frequency decreased. The lack of fire has allowed woody species such as juniper to encroach upon native perennial grasses and forbs.

Culver Middle School students assist in fish surveys in the Crooked River watershed in eastern Oregon.

David Nolte, Trout Unlimited

In addition, heavy grazing by livestock at the turn of the century significantly altered rangeland plants. Overgrazing of riparian (streamside) areas resulted in unstable streambanks, increased stream sedimentation, and reduced some areas’ ability to capture and store water. Undesirable nonnative species of plants such as cheatgrass and medusa-head rye have invaded sagebrush ecosystems, outcompeting native grasses and forbs and reducing forage and cover for wildlife and livestock. The reduction in native species has created a more simplified and less resilient rangeland ecosystem.

Local ranchers, environmental organizations, and government agencies are working together to reverse these trends. In the Trout Creek Mountains in southeastern Oregon, for example, these partners altered grazing practices to repair damage caused by more than 100 years of season-long grazing. Their efforts are leading to ecosystem improvements, most notably measured by an increased in threatened Lahontan cutthroat trout inhabiting associated streams.

Nonnative Weed Invasions

The spread of invasive, nonnative (exotic) plants is causing severe damage to entire ecosystems in the Columbia River Basin. In addition to cheatgrass and medusahead rye, leafy spurge, spotted knapweed, rush skeletonweed, and yellow starthistle are spreading rapidly into rangelands, forestlands, recreation areas, roadsides, and waterways in eastern Oregon, eastern Washington, western Montana, and Idaho.

Yellow tarthisle

Elizabeth Rieben

BLM Weed Demonstration Areas within the basin demonstrate how people can work cooperatively to prevent and control weeds. For example, where Idaho, Oregon, and Washington meet just north of the famous Hell's Canyon, a community team representing state and local government as well as private industry worked side-by-side to map and inventory over 8,000 hectares that were highly susceptible to broad-scale degradation from nearby massive invasions of yellow starthistle.


Elizabeth Rieben
Weeds such as yellow starthistle are threatening to ruin the delicate and diverse canyonlands where Idaho, Washington, and Oregon meet.

This and other weeds are well on their way to permanently degrading the canyon landscape, a delicate and wild system home to at least 24 rare plant species and over 400 vertebrates, including mule deer, bighorn sheep, and golden eagles. The team is implementing control methods, such as hand pulling and herbicide spraying, but the job is so large that unless all landowners join in, and unless the spread of these infestations into new areas is prevented, weed control efforts ultimately will fail.

Aquatic Ecosystems

The health of aquatic ecosystems is critical to the entire Columbia River Basin. About 80 percent of all fish and wildlife in the basin use the riparian (streamside) habitat at one time or another. Timber harvesting, livestock grazing, road construction, and mining have all dramatically changed aquatic ecosystems, affecting both water quality and quantity and altering water flows and temperatures. This, in turn, affects the types of wildlife, fish, and plants that can survive in the area.

Streams and rivers of the Columbia River Basin once were freeways for millions of salmon returning each year to spawn. Today, only about 10 percent of these fish have survived. At least 67 distinct salmon runs are gone and many more are at risk.


Salmon and other fish need aquatic habitat areas that are shaded and cooled by trees and protected with undercut banks vegetated by healthy grasses and sedges. The water should have plenty of woody debris where fish can hide and rest, as well as plenty of aquatic insects to eat. Not surprisingly, relatively untouched streams within wilderness or roadless areas tend to have the healthiest aquatic habitat conditions in the basin. Central Idaho retains some of the highest-quality fish habitat due to its remoteness and high elevation. Few anadromous fish can take advantage of these habitats, however, because fish passage is impeded by over 450 large dams, as well as many smaller ones, in the basin.

Dams restrict the migration of anadromous fish species, blocking them from important habitats and increasing mortality of juvenile salmon traveling downstream. Some of these dams have fish passage facilities, but many smaller dams do not. Turbines kill juvenile fish. Dams also cause migrating fish to spend more time in slower and warmer waters created by reservoirs. Physiological stress and increased susceptibility to predators result as fish congregate in smaller areas.

Public and private water managers are working to increase the survival of these fish by increasing water flows during certain times of the year to help fish travel over the dams, installing fish ladders to guide fish around the spillways, and hauling juvenile fish around dams in trucks or barges. Despite these efforts, however, dams still pose the greatest threat to the survival of native salmon and trout runs in the Columbia River Basin.

Loss and fragmentation of diverse habitat have also contributed to a decline in native fish diversity. Many salmon species inhabit a small portion of their former ranges, while many introduced nonnative species, including recreational species such as bass and brook trout, are widespread. Of 87 native fishes in the basin, 45 are recognized by state and federal management agencies as sensitive or species of special concern. Twelve species are either listed or candidates for listing under the Endangered Species Act, including bull trout and steelhead.

Aquatic Restoration Efforts

Local communities, including schools, are working with land managers on a number of aggressive aquatic habitat restoration efforts throughout the Columbia River Basin.

In central Oregon, for example, two teachers are involving students with ongoing watershed restoration efforts on the Crooked River, which winds through the Ochoco Mountains and the Columbia Plateau. With community support and financial assistance from organizations such as Bring Back the Natives, a national public/private initiative to restore native aquatic species, the teachers created a watershed-level environmental education program for K12 students in two school districts. The program draws on local experts who offer technical and financial assistance. In return, students provide the community with watershed restoration work and research. High school students have completed sediment studies, habitat surveys, and wild fish monitoring projects. Students also work on stream restoration and riparian plantings through a special greenhouse program to propagate cottonwood trees.


Older students teach younger students about watershed restoration at the "Fish Fest," part of the Crooked River Ecosystem Education Project in Oregon.

Youth from five Native American tribes also are working to restore salmon populations in the basin as part of Salmon Corps, a program sponsored by the Earth Conservation Corps involving 100 Americorps participants in Oregon, Washington, and Idaho. These young adults representing the Yakama Nation, Confederated Tribes of the Umatilla Reservation, Nez Perce Tribe, the Confederated Tribes of Warm Springs, and the Shoshone-Bannock Tribes are restoring 400 km of streambed and erecting 480 km of cattle-exclusion fences to enhance 29 salmon habitat areas.

Habitat Loss in Grasslands and Forests

The loss of steppe habitat (areas receiving less than 30 cm of rain per year) in the Columbia River Basin is having a detrimental effect on wildlife. Populations of both grassland and shrub-steppe species such as the sage-grouse, Columbian sharp-tailed grouse, sagebrush vole, upland sandpiper, grasshopper sparrow, and pronghorn are declining throughout the basin. In eastern Washington, the BLM and the Washington Department of Fish and Wildlife are working together to assist upland species such as sharptail and sage grouse by exchanging land with private landowners to acquire steppe habitats in large blocks. Much of the native steppe habitat has been converted for agricultural purposes. By exchanging isolated forested tracts and purchasing larger blocks of meadow steppe lands, the agencies hope to provide a safety net of habitat.

Populations of grassland and shrub-step species, such as sage-grouse and pronghorn, are declining due to a loss of habitat.

Larry Ridenhour, BLM

In the basin's forests, populations of cavity dwellers, including several species of owl, woodpeckers, and the northern flying squirrel, are declining due to fewer dead or dying trees. In areas near roads, fallen trees are often collected for firewood or other uses. Roads also pose other risks to wildlife. Many animals have been killed crossing busy roads and highways.

Populations of grassland and shrub-step species, such as sage-grouse and pronghorn, are declining due to a loss of habitat.

Jack A. Seeley

Neotropical migratory birds traveling between North and South America each year also have fewer and fewer safe stopover areas. Habitat is also an issue for the federally protected grizzly bear and gray wolf, which require large, uninhabited areas. Their needs and the needs of people living near them must be carefully weighed in planning for their recovery.

A New Management Approach

The Scientific Assessment confirmed that rangeland, aquatic, and forest health issues are intricately connected in the Columbia River Basin. Scientists concluded that any proposed management strategy must also link these issues across boundary lines and agency jurisdictions.

The rolling, fertile Palouse Hills in eastern Washington are composed of deep loessial (wind deposited) soils. Much of the nation's wheat is grown here.

Sandy Felsenthal/National Geographic Image Collection

A proposed strategy is described in two draft environmental impact statements released in June 1997. It calls for aggressive restoration of forests, rangelands, and watersheds. It emphasizes forest thinning and using prescribed fires during cooler seasons to decrease risks of large, severe wildland fires. It also calls for increased efforts to stem the tide of invasive weeds. The proposed strategy recognizes that people who live in the basin have a stake in its management many make their living from its rich natural resources. Although most of the basin is rural, several urban centers are among the fastest growing in the country. In addition, a number of Native American tribes and other traditional communities have interests in lands within the basin.

Spiny hopsage, a native shrub of the salt desert, grows on the alkaline flats of the Snake River Canyon near Boise, Idaho. American Indians ground parched spiny hopsage seeds to make pinole flour. It also provides forage for livestock and big game.

Larry Ridenhour, BLM

Monitoring watershed conditions at many different scales will be a key to measuring progress as National Forests and BLM Districts in the Columbia River Basin begin to implement this plan. Monitoring tools include looking at changes in water quality and quantity, streamside vegetation, extent of weed invasions, native fish and wildlife populations, and numbers and sizes of severe wildland fires. But the ultimate measure of success will be known many years from now, when people living in the basin continue to enjoy a high quality of life, sustained by the basin's rich natural resources. With their involvement and support, federal, state, and private scientists and land managers hope to restore ecological health to the basin so future generations will continue to be captured and enraptured by its wild beauty.

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