Dams and Their Ecological Consequences

Science Center Objects

Scientists in the Aquatic Systems Branch have been studying the impacts of dams on riverscapes for more than two decades. Our scientists have written many reports on the effects of dams on recruitment of bottomland pioneer trees, such as cottonwood, along the Upper Missouri River and the Bill Williams River, and the effects of dams on channel geometry and vegetation throughout the Great Plains. Understanding the effects of dams and the relations between flow, sediment, and vegetation have allowed AS Branch scientists to provide valuable information for managing flow releases from dams to enhance native tree recruitment, or to remove exotic plant species that are encroaching on the channel along several rivers. Recently, AS Branch scientists are monitoring changes to flood plain vegetation along the Elwha River in Olympic National Park in response to the removal of two large dams. This study will provide lessons and guidance to the design and planning of future aquatic restoration efforts. We also study the ecological consequences of the experimental pulse flow in the Colorado River.