The Columbia River is the fourth largest river in North America. Originating in British Columbia, it flows 1,214 miles to the Pacific Ocean near Astoria, Oregon. Size, however, is only one aspect of what makes the river particularly unique. Uniqueness is also evident by looking at the Columbia River Basin. The Basin’s geologic history, topography and hydrologic cycle provided settlers with an abundance of natural resources. Precious metals and fertile soils are part of the story. So is the abundance of fish and wildlife within the area. With mankind’s ability to tap into these natural resources, Northwesterners have taken advantage of opportunities to improve their quality of life and economic well being.
This section describes some of the benefits which stem from society’s interaction with the Columbia River Basin. These benefits include low cost and reliable electricity, flood control, irrigation, navigation and recreation. The reason for focusing on these benefits, unlike forestry and mining, is that they relate most directly to society’s use of the Columbia River system.
Before looking at these benefits, let’s first take a closer look at how the Basin was formed and nature’s continuing interaction with it. Within the Basin, there are 2,500 square miles of waterways and lakes. The Columbia River and its tributaries account for about 219,000 sq. miles of drainage in seven western states. This drainage occurs within the context of an intricate relationship between the hydrologic cycle and the resulting water that flows through the topography of the region. Understanding this relationship and how people have chosen to interact and influence it is critical to understanding both the past and future development of the Northwest.
Let’s begin by looking at the topography of the Columbia River Basin. Physically, the Basin consists of the Rocky Mountains to the east and north, the Cascade Range on the west, and the Great Basin to the south. The Columbia River begins its flow through this Basin from Canada’s Rocky Mountain Range and eventually becomes the border between Oregon and Washington. Along the way, the Columbia is fed by a number of major tributaries. The three largest include the Kootenai, the Clark Fork-Pend Oreille and the Snake rivers. Others include the Payette, the Sultan, the Cowlitz, the Santiam and the Willamette. While each of these tributaries has its own unique characteristics, the Columbia River and the Basin represent the larger whole to which they are all connected.
Over millions of years a series of cataclysmic events shaped the Basin’s topography. During the Eocene and Oligocene periods that date back 20 to 50 million years, there were tectonic shifts that helped form mountainous areas and volcanic activity that resulted in floods of molten lava. Seventeen million years ago, scientists believe a giant meteorite struck southeastern Oregon, causing floods of basalt lava. As this lava spilled across the western lowlands, the Columbia Plateau began to form. When the lava cooled and cracked, it formed vertical columns of basalt that are still visible today. These volcanic fires were followed by the deep freeze of the ice age.
The big glaciers of the last ice age covered all the northern fringe of Washington and Idaho. In Washington, these glaciers advanced down the western part of the Okanogan Valley about as far south as Chelan. In Idaho, a finger of the ice sheet came down to Sandpoint, where it blocked the mouth of the Clark-Fork River. In so doing, an ice dam one-half mile high was created.
This ice dam resulted in the creation of Lake Missoula, which was 2,000 feet deep and stretched hundreds of miles into Montana. Approximately the size of Lake Ontario, about 15,000 years ago the dam burst all at once and Lake Missoula was drained. As the resulting flood carved out 50 cubic miles of earth, deep channels were formed and areas such as the Columbia Gorge were further widened and shaped. It dug riverless canyons such as Dry Coulee, Spring Coulee and Moses Coulee in a matter of days. And it formed the Grand Coulee, which is fifty miles long, up to six miles wide and nine hundred feet deep.
Floods also swept into Oregon, covering much of the Willamette Valley. Where Portland stands today, flood waters were thought to be 400 feet deep. Scientists now believe such floods occurred repeatedly as the continental ice sheet came and receded. With all these cataclysmic events, the Northwest’s topography took shape.
As water flows through this topography, the continental divide causes the river system to “tilt” toward the Pacific Ocean. Entering the United States in Western Montana, the continental divide stretches south to the Idaho border. The divide follows this border east into Wyoming and then heads south through Colorado. Rivers west of the divide, such as the Columbia, flow through the region’s topography and toward the Pacific Ocean.
As the water flows to the Pacific, the Columbia River is second only to the Missouri-Mississippi River System in terms of annual run-off. But because of the region’s topography and its gradients, water flows through the Columbia River System like no other river system in the United States. This unique combination and the hydrologic cycle is the reason that almost half of all hydroelectric generation in this nation comes from the Northwest.
The importance of the hydrologic cycle in creating a unique relationship between water flow and topography cannot be underestimated. To the west of the Cascades, precipitation largely falls in the form of rain during the winter. To the east of the Cascade Mountain Range, precipitation largely falls in the form of snow during the winter months. Stored in deep snowpacks found in mountainous areas, spring time warmth is the catalyst for water being released into the river system. This runoff causes rivers to rise and streamflows to peak during May or early June. In fact, 60 percent of natural runoff happens from May through July.
Annual precipitation, of course, is not constant. Nor are variations in sunlight and air temperature. So how much a river rises, or if it floods, largely depends on how these variables mix together during the year. By looking at streamflows at the Dalles in Oregon, one can see how much the hydrologic cycle can vary from year to year.
Flow on the Columbia River is generally measured at The Dalles, Oregon. Historic records show an annual pattern with peak
flows in the late spring. Source: U.S. Bureau of Reclamation, U.S. Army Corp of Engineers, and Bonneville Power
Administration. The Columbia River System: The Inside Story, Portland OR, 1991, p.6
As the hydrologic cycle occurs, 130 million acre feet of runoff flows through the topography of the Columbia river system annually. By comparison, that is more than eight times the runoff than the Colorado River System.
Technology has been society’s tool for using the power of this relationship between water and topography to maximum advantage. Combined with the Northwest’s other natural resources, such as fertile soil and precious metals, settlers were drawn to the Basin. The following statistics provide some economic perspective:
- The gross national product for the Northwest grew from a few thousand dollars in 1792 to more than $300 billion in 1992.
- After adjusting for inflation, the combined personal income of Northwesterners doubled from 1929 to 1949, doubled again by 1969, and doubled again by 1989.
In short, the Columbia River Basin is an essential reason for the Northwest being a dynamic and highly prosperous region within the nation and the world. Hydropower, flood control, irrigation, navigation and recreation are specific benefits that the uniqueness of the Basin and its river system provide.