Rivers get over the dam
For many older US dams, environmental damage outweighs economic value
Though it was a whimper, and not a roar, when the Kennebec River hydroelectric dam came down last week in Augusta, Maine, scientists and environmentalists stood at attention.Skip to next paragraph
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This was the first time in United States history that the federal government had deemed a dam's environmental damage greater than its economic benefit and refused to renew its license. The precedent may open the floodgates for more dam removals.
With the dam-building era long past, scientists are now learning of the environmental damage dams wreak on river ecosystems. This includes burying fish-spawning areas with silt and debris, blocking fish migration, and preventing the natural spread of plants and nutrients.
Dams have also contributed to the extinction of 106 native salmon and trout stocks in four Western states, despite hatching programs and fish passages.
Added to this, dams all over the US are crumbling. One-quarter of the nearly 75,000 around the country are more than 50 years old, their average life expectancy, according to American Rivers, an environmental group in Washington, D.C.
But until recently, dam removal was unthought-of, and scientists could only speculate about how rivers would respond to a release of their penned-up waters.
A blossoming movement to restore rivers across the country to their natural, free-flowing state is, at last, starting to give scientists their chance to study the ecological effects of dam removal.
"There are a lot of important questions that scientists are grappling with, and we are just recently being given the opportunity to do the much-needed research," says LeRoy Poff, a professor of biology at Colorado State University in Fort Collins.
The Edwards Dam on the Kennebec will offer one such case study. After 162 years of feeding power to local industry, the 25-foot-high dam was breached with backhoes July 1 and will be fully removed by Thanksgiving.
The Kennebec, the second largest river in Maine, and the Androscoggin River share the ecologically unique Merymeeting Bay, one of the largest freshwater tidal estuaries in the US. Now that the Edwards Dam has been breached, scientists believe freshwater from the river will have a much greater influence on the estuary.
Jim Stahlnecker, leader of the Kennebec River Restoration Project for the Maine Department of Marine Resources, has been collecting data in an effort to make a before-and-after assessment of dam removal.
Using historic survey reports of the river conducted by the Army Corps of Engineers before construction of the dam, the Maine Department of Marine Resources has developed a scheme of how the Kennebec may adjust now that the dam is gone.
According to Mr. Stahlnecker, the predictions are elegantly simple. The river's natural flow will be restored, providing a friendlier environment for native species of plants and animals.
At least 10 migratory fish species will have unimpeded access to 17 miles of the Kennebec, the longest stretch of their habitat north of the Hudson River.
Although the river may restore itself quickly, the battle to remove the dam took 10 years. It finally came down to an environmental impact statement that declared relicensing the dam would cost almost two times as much as removing it.
The power it generated (1/10th of 1 percent of Maine's total use) did not justify the environmental damage.
When repair is not worth it
Edwards is not unique. In many cases, the cost of repairing dams outweighs their economic benefit. Since 1993, when the first of these older dams came up for license renewal, the public and governmental agencies have used the Federal Energy Regulatory Commission relicensing process as an opportunity to push for dam removal. The FERC licenses about 2,000 privately owned hydroelectric dams.
Now hundreds of FERC dams are coming up for license renewal. The FERC-licensed Condit dam, on the White Salmon River in Washington State, could be the next in line for removal.
But the FERC relicensing process is not the only way dams are being slated for removal. For the first time, a dam will be removed following a collaborative effort between a utility company and the government
In an unprecedented case, Oregon Governor John Kitzhaber announced last month the removal of two dams in the Sandy River Basin, about 30 miles east of Portland.