| OCR Text |
Show In western Oregon the Willamette Valley, a large tributary valley of the Columbia, lies west of the Cascade Mountains. This is a populous and productive area where many conditions differ markedly from the remainder of the Columbia Basin east of the Cascades. The higher parts of the Cascades and Rockies are generally humid and locally may have very heavy precipitation. However, lower slopes and the lower mountain valleys have only 10 or 20 inches of rainfall annually, not enough for maximum agricultural production. The wide interior pla- teaus, embracing nearly all the land suitable for cultivation, are either semiarid or near-deserts. Moreover, most precipitation comes in winter. In summer, when crops are grown, rainfall is very light. Tlrus the total water resources are enor- mous but in a large part of the basin moisture falls where it cannot be used directly, or during the wrong season for agricultural purposes. On the other hand, most of the moisture falls at high ele- vations, not distant from the ocean, thus affording the highest hydroelectric power potential in the Nation. Within tJie broad area of dry, interior plateaus are two extensive sections of comparatively flat land-the Snake River Plain and the Columbia Plateaus. Both areas are composed of enormous sheets of horizontal lava flows covered with surface materials of various kinds, many of which are suit- able for diverse agricultural purposes. The Snalce River Plain is a great crescent-shaped area extending from the Teton Mountains in ex- treme eastern Idaho around the southwestern mar- gin of the northern Rockies to western Oregon. To the northwest, mainly in Washington and Ore- gon, the Columbia Plateaus make up a second great dry expanse. Their surface features are somewhat similar to those of the Snake River Plain. Much of this area is covered by fine-tex- tured, wind-accumulated material, highly prized as an agricultural soil, but very susceptible to ero- sion. These two great areas are separated by a wide belt o:f rough hill land and low mountains, of which the Blue Mountains are the most prominent feature. The low«r, drier mountain slopes and the dry interior pla-teaus, as might be expected, are covered by sagebrush and other types of desert shrubs and grasses. TIhe humid mountains which surround them are covered with forests of varying density and type. These forests, together with those of the coastal area, contain the largest reserve of standing timber in the United States. The People: Distribution, Population Growth, and Characteristics Although the average density of the population is over 14 persons per square mile, the distribu- tion is very uneven. Most of the inhabitants are concentrated in relatively small areas where physi- cal conditions have favored the development of compact irrigated farm communities, in lumbering centers, in mining communities, in the relatively humid Willamette Valley, and in cities. The mountain areas are uninhabited or contain scat- tered ranches in the valleys. Wide expanses of the interior plateaus support only a very sparse population. The population of the Columbia Basin increased from 2.2 millions in 1940 to over 3.1 millions in 1949. This represented a rate of increase of 41 percent as contrasted with a national population increase rate of less than 15 percent. Much of the increase was due to migration into the area. Much of this large increase in population occurred in a few major centers, and wide areas of the more sparsely populated sections of the region experienced little growth. The populous Puget Sound area of western Washington, including such cities as Seattle and Tacoma, although not in the basin, is really one with it for many economic considerations. The Columbia Basin is its hinterland, and its economic life is closely tied to that of the basin. The Puget Sound area's million or more people must be taken into account in analyzing the effects of develop- ment, including the distribution of benefits. The Economy The economy of the basin which sustains this population is still relatively immature. The basin is primarily dependent on the extractive industries and production of raw materials: timber; grain, livestock, wool, and other farm products; fish; and minerals. Recreational services also are a signifi- cant source of income. Among the primary activities, agriculture, forestry, and fishing are much more important in the basin economy, relatively, than in the national economy. |
