All forms of renewable energy impact the environment in various ways. Although hydroelectric power is one of the cleanest sources of energy, it does alter or impact its surroundings. One of the chief concerns is the change in water quality. Specifically, with conventional hydro plants that rely on a reservoir, water often becomes warmer, loses oxygen content, experiences siltation, and gains in phosphorous and nitrogen content.
Another major issue is the migration of river aquatic life. Many species of fish including salmon, shad and sturgeon migrate up or downstream to spawn every year and dams can block their natural range. Fish ladders, fish lifts and other upstream and downstream fish passage techniques are being utilized to enable fish and other aquatic life to pass dams and hydroelectric facilities. This issue is a concern for all dams, including hydroelectric facilities.
The majority of the opposition to hydroelectric facilities centers on new developments that dam a river for the first time. These challenges may include the need to relocate people, the loss of culturally important sites, loss of land, methane gas emissions from decaying material in a new reservoir, siltation and downstream flow shortages. This challenge also impacts new water supply reservoirs that are being developed to provide drinking water as our population expands. Due to these reasons and several others, most hydroelectric development in the U.S. is currently focused on existing non-powered dams.
The dam and hydro profession today is a multi-disciplinary body including environmental specialists, ecologists, biologists, social scientists and economists. Together they represent a wealth of expertise which can ensure that future projects are planned, constructed and operated with full respect for society and the environment.