


Ever since, nature has come rushing back. Salmon have been spotted swimming upriver. The tender shoots of alder and cedar have begun to recover their turf. Meanwhile, kayakers like Mr. Kuthe make frequent trips downstream to see how the river is reclaiming its old bed -- and to discover new whitewater rapids that may have formed.

''It looks so different, even from just a few months ago,'' he said, as he eased his plastic kayak near a concrete wall that once anchored the dam.

A lot of rivers are starting to look different. In the 1950s and '60s, a dam went up in the United States every six minutes to generate electricity, provide irrigation water and protect against floods, according to the United States Forest Service. As a result, there are an estimated 75,000 aging dams blocking rivers large and small today.


The Marmot, built in 1913, is a prime example. The dam's owner, Portland General Electric, chose to replace it with cheaper power sources rather than pay for repairs and upgrades. Others are known as L.D.D.'s in the dam business, or ''little dinky dams,'' that few would miss.


''Many of these dams just don't make much sense,'' said Thomas O'Keefe, a spokesman for American Whitewater, a river stewardship group based in Cullowhee, N.C. ''You have these dams that have huge ecological impact that don't produce a lot of power.''

River by river, old dams are being dismantled at a rate of about 40 a year, according to American Rivers, a nonprofit conservancy in Washington that advocates for dam removal. While that's good news for fish and wildlife, it's also benefiting paddlers like Mr. Kuthe who are flocking to these uncorked rivers in search of newly formed whitewater rapids and other paddling adventures.


''There's also the excitement of the unknown,'' said Tao Berman, a professional kayaker who lives in White Salmon, Wash., not far from the White Salmon River, which is known for its whitewater runs by kayakers the world over.


''I just can't wait to see it,'' Mr. Berman, 30, said. ''Is it going to unearth a great play spot, or is there going to be one really steep, difficult rapid? I have no idea.''


