Dams and river crossings often block the migration routes of stream-dwelling fish in addition to their better-known effects preventing salmon from spawning in upper river reaches. Relatively little is known about the movements of mountain whitefish (Prosopium williamsoni) in the Pacific Northwest, despite their widespread distribution. In the upper Cedar River, Washington, mountain whitefish had been absent above the Landsburg Dam, constructed in 1901, until a fish ladder was built in 2004 that allowed their upstream passage. Mountain whitefish undergo extensive migrations within larger rivers, and the fish ladder was expected to open up more than 33 km of suitable habitat, especially in deeper stretches of the river. Immediately after the fish ladder was installed, small numbers of mountain whitefish were observed above the dam, and numbers continued to increase for seven years before leveling off. These results show that wild fish can rapidly re-establish in areas above dams, when stream barriers to migration are removed, providing hope for river restoration in other regions. The paper was led by Peter Kiffney of the Northwest Fisheries Science Center, NOAA, included two SAFS coauthors, Ben Cram and Thomas Quinn, and appeared in the journal Ecology of Freshwater Fish.