October18, 2001: A river barge moves cargo along the Columbia River in Oregon to the Port of Portland and markets in Asia. .Measured by the volume of its flow, the Columbia is the largest river flowing into the Pacific from North America, and is the fourth-largest river in the United States. The river's heavy flow, and its large elevation drop over a relatively short distance, give it tremendous potential for the generation of electricity. It is the largest hydroelectric power producing river in North America, with fourteen hydroelectric dams in the United States and Canada...The Columbia and its tributaries are home to numerous anadromous fish, which migrate between small, fresh water tributaries of the river and the Pacific Ocean. These fish,especially the various species of salmon, have been a vital part of the river's ecology and the local economy for thousands of years...The taming of the river for human use, and the industrial waste that resulted in some cases, have come into conflict with ecological conservation numerous times since Americans and Europeans began to settle the area in the 18th century. This "harnessing", as it was commonly described in the popular culture of the early 20th century, included dredging for navigation by larger ships, nuclear power generation and nuclear weapons research and production, and the construction of dams for power generation, irrigation, navigation, and flood control.