Lookout Point Dam (OR)

The driving force behind the dams and reservoirs constructed by the Corps has always been to improve our quality of life. These flood control, navigation, water supply, and hydropower projects were constructed to improve the developed environment of the communities in which most of us live and work.

Water resource projects can often improve the natural environment as well. For example, increasing flow  during the dry months enhances aquatic habitat, while reducing flows in periods of flood runoff helps prevent damage to vegetation and wildlife habitat along stream banks.

However, dams and reservoirs change the natural river environment, and there is often a price to pay for these changes. Examples are the loss of open-river environment when a dam is constructed, and changes in river ecology that come with changes in flow patterns.

Interior least terns nesting

New aerating turbine like that  being installed at J. Strom Thurmond Dam (SC)

In recent years the public has come to realize that we need a balance between improving our immediate daily environment and in preserving the natural environment around us. The Corps' response is a concerted effort to mitigate dam and reservoir impacts to make the operation of these projects more compatible with the environment. Three examples illustrate this.

In the southeastern states, dissolved oxygen (DO) levels below dams may get so low in the summer that aquatic life is severely impacted. The Corps is improving DO levels by using aerating turbines and injecting oxygen directly into the streamflow.

When the six large reservoirs on the Missouri River were constructed, the emphasis was on navigation, flood damage reduction, irrigation, and generation of electric power. Fish and wildlife were also included in the development of reservoir operating plans. As part of its responsibilities to provide these multiple project purposes, the Corps continually assesses how well operating plans are satisfying basin wide water needs. One such need has been the improvement of habitat for endangered species such as pallid sturgeon, piping plover, and the threatened interior least tern. This has led to a thourough review of the operating plans to see if a better balance can be given to environmental factors.

Salmon smolts

Columbia River salmon may be the biggest environmental challenge facing the Corps today. The Corps is working closely with the fishery agencies, the Tribes, and other interests to restore the declining salmon runs. Already, more than three billion dollars have been spent on research and dam modifications to improve salmon survival. The problem is not yet solved, but all parties are working diligently toward a solution - one that will restore the fish runs while ensuring that the projects continue to serve the purposes for which they were constructed.