The Willamette Valley of Oregon has been the setting for two major environmental modification programs begun in the late 1930's. One was the flood control program of the Corps of Engineers. The Corps in association with other water resource developers and local groups of citizens prepared and implemented a plan to control the valley's winter flood waters. The second environmental modification program was designed to improve the quality of the Willamette River which was particularly poor during the summer low flow period. The water quality enhancement program was begun, by a vote of the people, in 1939 when, by initiative petition, they created the Oregon State Sanitary Authority. The report indicates the kinds of public participation characteristic of each, identifies the settings for this participation, and determines the factors which limited and stimulated public participation.