The Willamette River, in its natural state, has been subject to annual flooding, at times severe. Draining an area of over 11,200 square miles, the river supplies water for agricultural, industrial, municipal, and domestic purposes in the Willamette Valley. Between November and February, heavy rains often fall on the deep snow in the Cascade Range.

In the 1890s, when the rains were accompanied by a sharp temperature rise and heavy precipitation in the valley, the Willamette River could experience major floods. The flood of June 1894 was one of the worst such high-water events of the nineteenth century in Oregon. The effects of the high water on the Willamette were hightened by similar flooding on the Columbia River at the same time.

That year, floodwaters inundated agricultural land, eroding soils, killing livestock, and damaging farm buildings. The rampaging Willamette flooded towns along its banks, destroying mills, docks, warehouses, and transportation facilities. At Portland, the river reached a high-water mark of 33.5 feet, the worst flood ever recorded in the city. Surging high water covered 250 square blocks and knocked out public utilities, warehouses, and docks. Two drawbridges were stuck open, limiting travel between the east and west sections of the city. Businesses sold merchandise from their second-floor windows or operated from boats floating on city streets.

With more than a hundred miles of track washed out, the Union Pacific Railroad suspended service to the city. The aftermath of the flood was nearly as unpleasant as the flood itself, requiring a major cleanup of dead animals, rotted fish, and sewage.