OCR Text |
Show Preservation of Present Assets and Existing or Authorized Facilities Flood Control The principal need for protection is against floods. The major 1948 flood on the lower Co- lumbia caused damages in excess of 100 million dollars, and minor floods occur almost every year in some part of the basin. Existing, in construc- tion, or authorized projects along the Columbia, Willamette, Snake, and other tributaries will reduce substantially the major flood hazards. Upstream storage and levee construction are the main ele- ments among the existing or authorized facilities. However, assurance of adequate protection will not be obtained until completion of construction on the main control plan and tributary basin plans. About 180 engineered projects having flood control func- tions are contemplated. Unless further experiment illustrates more efficient means of accomplishing flood control, it is to be assumed that there will remain need for engineered flood control projects in the basin for some years. Watershed Treatment Full use of the basin's waters over the longest possible period, and the preservation of many of the existing and possible facilities of most value to the basin, depend upon improved watershed man- agement. Problems of watershed management are less critical in the Columbia than in many other basins, but a number of acute situations demand attention. The sharply dissected relief of much of the basin, the light, easily transportable soils, and the aridity of the districts which contain much of the cultivated or potentially cultivable lands, all help to create erosion hazards. These in turn are sources of sedimentation, lowering the value of reservoir sites-a major regional resource. The major needs are as follows: Reforestation of cut-over lands, old burns, and other understocked forest areas.-The Forest Service estimates that 3 million acres of private lands and a million acres of national forest are in need of replanting. This is about 7 percent of the total forest lands of the basin (59 million acres). Until these areas are replanted they are detriments to proper water resources management in the for- ested parts of the basin. There also is need of resto- ration on parts of the public domain where forest is the normal cover. Arresting destructive cutting practices on pri- vate forest lands.-Large acreages of forest are still being subjected to clear cutting or other destruc- tive harvesting, thereby adding to erosion hazards in forest areas. The Department of Agriculture estimates that roughly three-fifths of the private forest lands of the basin are not properly managed either for protection of the water resources, or for the maintenance of their timber production capac- ity. Measures directed toward improvement of this condition are badly needed. Education of landowners and operators, Federal guidance of State legislation and regulation, and Federal finan- cial assistance will provide some direction toward this end. In some sections and especially in critical areas where private management cannot meet mini- mum standards for proper watershed management, provision for further public ownership may have to be made. Provision of proper fire control on all forest lands.-The need for an expanded system of access roads is critical. Roads are essential to adequate fire control as well as to the full and efficient utili- zation of the timber resource. Not one of the na- tional forests in the Rocky Mountain portion of the basin has access roads that can be considered ade- quate for fire-protection purposes. The possibility of catastrophic fires throughout the Pacific North- west is still great. Rehabilitation of eroding grazing lands.-In addition to the 7 million acres of national forest grazing land, at least 15 million acres of private grazing land and about 20 million acres of grazing land in the public domain are deteriorating rap- idly. They also contribute sediment to the basin's streams and promote undesirable runoff characteris- tics. For these reasons, as well as others, they are in serious need of improved management. Reduction of erosion in dry farming areas.- There are about 12 million acres of nonirrigated lands under cultivation in the basin, many of them on the Columbia Plateau of eastern Washington, northern Idaho, and northeastern Oregon. About 95 percent of the entire cultivated area must be farmed with care because of susceptibility to erosion or other unfavorable factors. About 6 million acres are being damaged at a critical rate. In the Palouse district particularly, steep slopes and light-textured soils, predominantly planted to grain, pour a heavy sediment load into all the streams. Within the basin as a whole, nearly 2 million acres should be retired from cultivation completely and much of the rest should be farmed in a more conserva- 23 |