The Current Magazine Fall 2016 - Page 10

When, Whether and How to Remove a Dam

Sometimes FERC (or other controlling public agencies) determine that a particular dam is doing more harm than good. Even when dam removal is identified as the best path forward, the process is difficult and expensive. Sediment that builds up behind the dam, which can contain toxins like mercury, must be addressed. Water flows during the removal process must be managed to minimize harm to downstream habitat and to ensure that people and structures will be kept safe during and after removal. And the whole process takes time: once removal is identified as the best option, obtaining the necessary permits and funding, physically removing the dam, and restoring habitat can take years or more.

The Elwha River in Washington State’s Olympic Peninsula is a dam removal success story. Two dams, the Elwha and Glines Canyon Dams, were removed between 2011 and 2014. A mere five years since dam removal began the river ecosystem has experienced a rapid recovery. Sediment has flowed downriver, recharging spawning beds and restoring the beach at the river mouth; vegetation is creating new riparian habitat on ground once covered by reservoirs; and fish and wildlife populations are rapidly rebounding. The first season after Elwha Dam was removed, more than 4,000 spawning chinook salmon were counted above the dam site, after 100 years of zero fish passage to the area.