Excerpts from the report: The Middle Willamette River Basin is located in the northern portion of western Oregon and includes the Willamette River and its tributaries from approximately river mile 32.7 to river mile 145.8 (fig. 1). The basin is bounded on the north and south by the Lower Willamette and Upper Willamette Basins, respectively, bounded on the west by the North Coast and Mid Coast Basins, and bounded on the east by the Deschutes Basin. The basin has a total area of about 5,426 square miles, about 45 percent of the entire Willamette River Basin area and about 5.6 percent of the total area of Oregon. The basin includes a major portion of five counties - Benton, Linn, Marion, Polk, and Yamhill - and a minor portion of five counties - Clackamas, Lane, Lincoln, Tillamook, and Washington. The broad objectives of the cooperative survey were to gather basic information pertinent to the use and control of water for agriculture in the area, to highlight such major water related problems as erosion, flood prevention, and drainage, and to outline a general program for water and related land resource management to be used as a background for future detailed study and planning.