Unknown Environmental Impact of Dam Removal

Data Centers built next to dams are assumed to have low cost power using renewable energy.  In the Pacific Northwest, Hydroelectric is not classified as renewable energy, and dams are viewed by many environmentalists as damaging.

A year from now the largest dam removal project will start on the Elwha River in the pacific Northwest. There are many environmentalists who champion dam removal.

Many of the dams in the eastern U.S. were built for water diversion, agriculture, factory watermills, and other purposes that are no longer useful. Because of the age of these dams, over time the risk for catastrophic failure increases. In addition, many of these dams block anadromous fish runs, such as Atlantic salmon and American shad, and prevent important sediments from reaching estuaries.

Many dams in the western U.S. were built for agricultural water diversion in the arid country, with hydroelectric power generation being a very significant side benefit. Among the largest of these water diversion projects is the Columbia Basin Project, which diverts water at the Grand Coulee Dam. The Bureau of Reclamation manages many of these water diversion projects.

Dams in the Pacific Northwest and California block passage for anadromous fish species such as Pacific Salmon and Steelhead. Fish laddersand other passage facilities have been largely ineffective in mitigating the negative effects on salmon populations. Bonneville Power Administration manages electricity on 11 dams on the Columbia River and 4 on the Snake River, which were built by the Army Corps of Engineers.

Seattletimes covers the largest dam removal project scheduled to start next year.

Elwha River's coming dam removal has scientists flooded with unknowns

Scientists see much to learn when two dams come down on the Elwha River, beginning about a year from now in the largest dam removal project ever in North America

By Lynda V. Mapes

Seattle Times staff reporter

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ELWHA RIVER, Clallam County — From all over the country they came to ponder this river: its gravel, its teal-green waters, its shores and mouth and mostly its future as the site of the largest dam-removal project ever in North America.

Sweeping north from Mount Olympus to the Strait of Juan de Fuca, the Elwha has been collared by two dams since the early part of the 20th century. Both will be taken out chunk by chunk, releasing some 18 million cubic yards of sediment impounded along with the river's flow. The process will take about three years, beginning next June.

With $350 million allocated for the project.  There is no money for scientific research in the budget.

Oddly, for its importance, Elwha research is a shoestring effort. The $350 million federally funded restoration project includes no money for scientific study. So as they toured the river corridor, the scientists were framing potential research questions to propose for funding by agencies, universities and other sources.

The environmental impact of dam removal at this scale is unknown.

"It's the first time anyone has done a staged, step-by-step dam removal of this scale," Randle said. "It's the largest controlled release of sediment ever in North America, and a very different process than we've seen elsewhere."

So how do you the decision makers and environmentalists know the dam removal is better for the environment?  It would seem logical that how the dam gets removed has a huge influence on the impacts to issues brought up in the article.

"We built a model of this, but I've never actually stood on it," said Gordon Grant, research hydrologist with the U.S. Forest Service research station in Corvallis, Ore. "How does the river adjust to the change in level? You have a tiger by the tail, and the only knob you have to turn is how quickly you take it down. What's upstream will drive what is downstream, and that is what makes this such a juicy problem.

"I can't think of another analogue anywhere for the experiment this river is going to be. It's a natural laboratory unlike any other."

It will take three years to remove the dam and many more years to see the environmental impact.

What is environmental impact of dam removal?  We don't know.