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construction of the Avon cut-off through the delta to carry 120,000 second-feet, the improvement of the present delta channels to carry 100,000 second-feet, the enlargement of the river channel above the delta to a capacity of 220,000 second-feet, and bank protection in the reaches above. From incomplete data it appears feasible that floods on the Puyallup could be controlled by construction of a detention reservoir at Mud Mountain. Further protection along this stream in the vicinity of Tacoma can be secured by means of channel enlargement and levees. The best results on the other streams can be secured by a coordinated plan for the raising of existing levees, revetment work, and the enlargement or clearing of constricted sections.

INITIAL DEVELOPMENT

19. Additional surveys and accurate estimates of cost are necessary before a final plan for the protection of these areas can be adopted. The cost of such studies and preliminary estimates of cost of the proposed improvements, arranged in the order of merit, are as follows:

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The introduction contains a general discussion of the problems of the utilization of the water resources of the Pacific region as a whole and should be considered in connection with the chapter on the Columbia River Basin.

1. General. The report contained herein covers the main Columbia River and its tributaries except the Snake and Willamette Rivers. Separate reports are being submitted on the two latter streams.

2. Description.-The principal headwater systems of the Columbia River are the Columbia River proper and Kootenai River, both of which rise in British Columbia, and Clark Fork, which drains portions of Montana and Idaho, and enters the Columbia just above the international boundary and below the mouth of the Kootenai. The Columbia River crosses the international boundary in northeastern Washington and continues southward for about 425 miles to the mouth of its main tributary, the Snake River, where it turns west and flows along the Oregon-Washington boundary for a distance of 325 miles to its outlet into the Pacific Ocean. Its total length is about 1,210 miles, and its total drainage area about 259,000 square miles, of which 39,000 square miles is in British Columbia and 109,000 square miles in the Snake River Basin. The important tributaries, other than those hereinbefore mentioned, are the Kettle, Spokane, Okanogan, Chelan, Wenatchee, Yakima, Umatilla, John Day, Deschutes, Lewis, and the Cowlitz Rivers. (See accompanying map.)

3. The bulk of the drainage area lies between the Continental Divide and the Cascade Range. The mountain headwater regions are covered with forests, as is the Cascade Range. The largest extent

of open country is the Columbia Plateau, a high tableland bounded on the west by the Columbia River, on the north by the Columbia and Spokane Rivers, on the east by the Bitter Root Mountains, and on the south by the Snake River divide. On the north and east this plateau is indented by many dry stream gorges, of which the Grand Coulee is the most important. From Rock Island Rapids to the Cascade Range, the Columbia River and its tributaries, in general, flow through canyons of varying depth and width with concentrated rapids and no flood plains. High, rolling semiarid plateaus are found in this section and occasionally bench lands occur which can be irrigated from the river or its tributaries. West of the Cascade Range the valley of the main stream widens and the stream is bordered by intermittent extensive lowlands that are overflowed during flood periods.

4. Population and industries.-The economically interdependent portion of the Pacific Northwest concerned in the development of the Columbia River has a population of over 3,000,000, of which 60 percent is rural. Approximately 40 percent of the population resides east of the Cascades. Portland, with a population of 302,000, and Seattle, with a population of 366,000, are the principal deep-water ports serving the Columbia River Basin. The only interior city in the watershed with a population over 100,000 is Spokane, which has a population of 116,000.

5. Agriculture, with its related industries, is the principal activity in the Columbia Basin. Grain, over 50 percent of which is wheat, destined largely for foreign markets, is raised on the upper plateau regions under dry-farming methods, and fruit, potatoes, and hay are important crops raised under irrigation on the tributaries. Much of the fruit is packed or canned and shipped to foreign and eastern markets. The hay is used locally as winter feed for livestock. Livestock and dairying with their related industries are growing.

6. The manufacture of lumber and timber products is the major industry in the area west of the Cascades. The annual capacity of lower Columbia River mills is over 3,820,000,000 board feet per annum and related industries have been established around these mills for the manufacture of sash, doors, boxes, crates, and furniture. Wood pulp and paper manufacture have grown to importance during the last decade.

7. Fishing is an important industry for about 15,000 commercial fishermen. About 73 percent of the catch consists of salmon caught in the Columbia River. The major part of the catch is canned locally and shipped to outside markets. Any dams built on the main stream should have adequate facilities for passing the fish.

8. Rainfall and run-off. The climate of the basin is characterized by the existence of a well marked wet and dry season in each year. The maximum rainfall usually occurs in December and declines to a minimum during the growing season of July and August. Rainfall in the basin varies from a maximum of about 150 inches in the Coast Range to a minimum of 6 inches along the central portion of the Columbia. The mean annual flow of the Columbia River at The Dalles, during the past 50 years, was about 200,000 second-feet. Minimum flow occurs during the winter, the normal low-water discharge being about 50,000 second-feet. Maximum floods, caused by warm rains. on the headwater snow fields, occur during May and June. The

maximum flood of record, with an estimated discharge of 1,200,000 second-feet at The Dalles, occurred in 1894.

PRESENT DEVELOPMENTS

9. Navigation.-The Columbia River has been improved for navigation. Depths over the ocean bar have been increased to 40 feet and a deep water channel, with a controlling depth of 35 feet to Portland and 28 feet to Vancouver, has been completed. Above the tidewater section navigation has been made possible by the construction of a flight of 2 locks at Cascade Rapids and a lateral canal, with 5 locks, around the obstructions between The Dalles and Celilo. The controlling depth over this section is about 8 feet. Some open river work has been done on the Columbia above Celilo but navigation above this point is hazardous due to high velocities and inadequate channel depths and widths.

10. The tonnage over the ocean bar, during 1932, amounted to about 4,650,000 tons. In the river below Vancouver, river boats, in addition to this ocean tonnage, carried about 1,250,000 tons of general commerce and hauled 3,450,000 tons of rafted logs. Between Vancouver and The Dalles there was about 300,000 tons of general commerce and 750,000 tons of rafted logs. There is no traffic at present above The Dalles.

11. Power.-Rock Island, a run-of-river plant with present installed capacity of 60,000 kilowatts and ultimate capacity of 180,000 kilowatts, is the only major hydroelectric development on the main stream. The total hydro installation in the tributary market area is over 1,000,000 kilowatts. A summary of existing hydroelectric developments on the tributaries under consideration, excluding plants with an installed capacity under 5,000 kilowatts, is as follows:

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12. No power storage has been developed on the streams under consideration, but Lake Chelan and Coeur d'Alene Lake are partially regulated in the interests of power. A power development, contemplating storage in Flathead Lake on Clark Fork, is partially completed; an application is before the Federal Power Commission for power development at "Z" Canyon on the Clark Fork, and a license has been issued for a development at a site 2 miles below Priest Lake: the latter development contemplates regulation of Priest Lake. Projects now under construction on the main stream are Bonneville, a combined power and navigation project with an ultimate installed capacity of 516,000 kilowatts, and a power development at Grand Coulee, which will have an ultimate installation of 1,800,000 kilowatts for the high dam. Both of these projects are being financed by the Federal Emergency Administration of Public Works.

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