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For the first time in 25 years, a hydroelectric dam is being built in Washington state.

It’s significant because in this place, where it rains constantly and rivers flow year round, dam has become a four-letter word to the well-entrenched environmental movement.

In fact, green groups have not only been successful in preventing the building of new dams, they’re also getting the federal government to spend billions of dollars removing dams to improve salmon runs.

“A lot of us that have been advocates for rivers for many years thought we were moving away from this era,” says Tom O’Keefe of American Whitewater, a group that works for preservation of whitewater rivers in the U.S. “We’ve got several dams in this area that we’re actually removing.”

The new dam under construction is different. It’s tiny compared to the massive projects that line major rivers, such as the Columbia and Snake. The Youngs Creek project in Snohomish County, Washington will produce just 3-4 megawatts, enough electricity to power 2,000 to 4,000 homes.

By comparison, the Grand Coulee Dam on the Columbia River puts out 6,765 megawatts, which is enough to power 4.5 million homes. Despite its low output, utility district officials see the small dam as a move in the right direction. “It’s a local resource,” says Scott Spahr of Snohomish County Public Utility District. “It’s renewable, and collectively, if you do a number of these projects, it might add up to a good part of our energy needs.”

Washington state is the largest producer of hydropower in the United States. Seventy-five percent of the state’s electricity comes from hydropower, a source that produces no greenhouse gas emissions, unlike burning coal and natural gas. And yet, environmental groups have long-accused the large dams in the region of damaging the iconic salmon runs. They’ve been battling the federal government through two administrations to have four dams on the Snake River removed.

Micro-hydro so far is not eliciting a major outcry from conservationists. A big reason is location.

Unlike the big dams like the Bonneville dam on the Columbia River, the mini-hydro projects are typically on small creeks near waterfalls that act as natural barriers to fish passage. The small dams proposed so far also do not store water, which has made a major dam critic at least willing to listen.

State Rep. John McCoy says the impacts of small dams may be acceptable. “If we want to talk about true run-of-river, where we might take a slice of water that comes through, goes through a generator and then back out into the stream, I’m willing to have that conversation,” says McCoy.

The federal government is also interested in mini-hydro. The Federal Energy Regulatory Commission, or FERC, recently approved a streamlined permitting process for small dams in Colorado. Twenty-eight states already have laws requiring utilities to sell more renewable power.

Seeing that the tide may be turning in its favor, the national Hydropower Association released a study showing that mini-hydro could easily be powering one million homes by 2025.

That, of course, would take a sizable investment by utility districts because to qualify as mini-hydro the generation capacity must be no more than 10 megawatts. Is it worth it?

Spahr believes it is. “It is as least as economical, if not more economical than wind or solar or the other renewable sources out there.”