OCR Text |
Show solely from surface sources, 125 from ground sources only, and 26 from both ground and sur- face sources. The daily requirements of these com- munities are in excess of 100 million gallons. In- dustrial use is estimated to be several times this amount. From the standpoint of surface water quantity there appear to be no problems that can- not be met by local water supply authorities. The natural quality of the ground and surface waters of the basin is generally excellent and, where pollution is not a problem, a minimum of water treatment is required to insure a potable supply. Most of the domestic surface water supplies are obtained at present from unpolluted tributaries of the Columbia. Industry has been forced to pro- vide extensive treatment of water in many cases because most of the larger establishments obtain their supplies from rivers adjacent to areas of concentrated population and consequent high pollution. Flood Protection Facilities Floods occur on the lowlands along the main stem, and in the valleys of the tributary streams. Floods are not periodic events in the Columbia Basin except in the Willamette Valley and a few adjacent streams, which have major flood prob- lems. Floods may come during the winter, when rains may combine with melting snow to give heavy runoff. The same is true for the Cowlitz, the Lewis, and some minor western tributaries. Losses from floods have been increasing as larger flood-susceptible areas are covered by more intensive use and expensive installations. Approximately 50 flood control projects have been carried out in the basin. Most consist of land diking and channel clearing. Three multiple-pur- pose reservoirs have flood control functions which have been completed in the Willamette River Basin. Two others will soon be added to the Wil- lamette system. Other works have been constructed on the other tributaries of the Columbia. Elements of a watershed control program have been partially attained in local areas but have been brought about only as an incidental result of related land programs having other major objectives. Related Land Programs Effective and comprehensive water control must begin at the place where the water falls. Un- less there is proper care of water on the land, run- off will be too rapid, floods will increase in fre- quency and intensity, sediment and erosional debris will clog the stream channels and reservoirs, low water flows will be reduced, aquatic life will de- teriorate, and the land itself will be damaged. Hence, associated land programs are of vital in- terest in a program of water control and develop- ment. They relate to private and public lands- forest, range, or cultivated farm. The use and ownership patterns of land within the United States part of the basin are varied and complex. Fifty-six percent of the land is in public ownership and control (nearly all in Federal own- ership), frequently lying in interspersed or even checkerboard fashion with private lands. Federal lands are under the care of the Forest Service, the Bureau of Land Management, the National Park Service, and the Bureau of Indian Affairs. There are 47 million acres in national forest. Of this, 29 million acres are classified as commer- cial forest and 18 million acres as noncommercial forest. These forests are managed primarily for timber production and watershed protection. Other important uses given the fullest possible con- sideration in their management are livestock graz- ing, recreation, and the production of fish and wild- life. One of the principal objectives of national forest management is the prevention of deteriora- tion of water resources. By careful logging methods and proper management of timber and grazing, erosion can be held to a practical mini- mum. In some places, however, current logging practices are accelerating erosion and creating sed- imentation problems. On 119 watersheds from which municipalities derive their water supplies, watershed protection is of primary concern. The national forests of the Pacific Northwest now supply summer forage for 270,000 cattle and horses and over a million sheep. However, 7 million of the 22 million acres of national forest ranges are overgrazed, with attendant damage to the water resources. To overcome this a reduction in the grazing intensity has been under way for some time. Concurrently, a range improvement program has been going forward. Some range reseeding work is being done. The Bureau of Land Management program of the Department of the Interior on public domain land consists of a large number of small projects designed primarily for local effect. They are de- signed to improve range conditions through better and more even use of the range, range reseeding, 13 |