The Willamette Basin is one of the better watered regions of the United States. The average annual precipitation of 63 inches results in a volume of more than 40 million acre-feet of water falling on the basin annually. Of this amount, about 26 million acre-feet runs off in the principal streams that drain the area. Most of the precipitation and runoff occurs during a few months in the winter, and natural water supplies are deficient during the late summer and early fall. Because of the diverse terrain, both precipitation and runoff are distributed unevenly. For this reason, it has been necessary to construct facilities to store the surface water and to drill wells to tap the ground water. As the population and economy of the basin grow, many additional water developments will be needed. The purpose of the Willamette Basin Comprehensive Study is to develop information on future water and related resource needs and to prepare a plan for meeting those needs. This appendix contains a description of the water resources, their distribution, and their variation at different periods of time throughout the Willamette Basin. These resources are described in terms of the climatic, geologic, and other environmental factors that influence and control the occurrence of water. The appendix provides statistical and interpretive hydrologic data necessary for broad-scale water-resources planning. These data are essential to the development of plans for meeting the basin's water needs and solving its water problems. (Author).

This appendix, together with Appendix B - Hydrology, and Appendix C - Economic Base, provides supporting data for the functional Appendices D through L. The general history and description of the basin, inventory of resources, and the broad relationship of those resources to use are discussed. The broad objectives of resource utilization and the pertinent physical, administrative, social, and legal aspects are contained in this appendix. The sequence of Appendices D through L reflects the alphabetical arrangement of potential project functions and consideration.

The Navigation Appendix relies upon supporting data contained in the Study Area, Hydrology, and Economic Base Appendices. There has also been an interchange of pertinent information between this and other appendices, particularly Appendix K - Recreation, and Appendix M - Plan Formulation. The data in this appendix provide the background for the navigation aspects of the main report. Navigation has been a part of the history of Willamette Basin since the earliest days of exploration and settlement. As time passed, the use of waterways for transportation changed progressively, influenced by the ever-expanding population, improvements in vessels, changing import and export cargoes, and the expansion of land-based transportation. The sea route to Willamette Valley was discovered in 1792. Captain Robert Gray, an American sea captain in search of furs for the China trade, located the mouth of Columbia River, and in the same year, Lieutenant William R. Broughton, under command of Captain George Vancouver of the British Navy, explored Columbia River in a small boat up to Vancouver Point, a few miles above the mouth of the Willamette.

The purpose of this appendix is to appraise the present municipal and industrial water supply situation, to analyze its future needs and development potential, and to evaluate the needs of subareas as a basis for making recommendations for measures which will serve those needs. Consideration of municipal and industrial water supply as a part of a comprehensive plan for development and management of water and related land resources is essential to provide a means for orderly development of water supplies. The scope of this appendix limits projection of municipal and industrial water supply requirements to the years 1980, 2000, and 2020. Appraisal of the 1980 requirements includes consideration of quantity, quality, and seasonal variations of supply and demand. The need identified is of an immediate nature and may be directly related to the development of a comprehensive plan for readily foreseeable developments. The long-range plans, which are naturally more conjectural, are more general in nature and point toward the needs of major subareas of the basin. The study area is confined to the Willamette Basin; however, the strong geographical and economic interrelations and interactions between the Willamette Basin, the Pacific Northwest, and the Nation will influence the level of municipal and industrial water demand in the basin. As an example, increased market area population will result in an enlarged market for processed food. Additional food-processing capacity will result in an increased demand for process water and water for the additional population supported by the industrial employment.