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.
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. 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.