The Corps Makes Room for Salmon, 1970

By 1970 the U.S. Army Corps of Engineers had built a staircase of dams across the Columbia and lower Snake: Bonneville (1938), McNary (1954), The Dalles (1957), Ice Harbor (1962), Lower Monumental (1969), and Little Goose — finished the very year this pamphlet was printed. Each dam required the Corps to confront the same problem: Pacific salmon and steelhead return from the ocean to spawn in the same upriver gravel where they hatched, navigating hundreds of miles against the current. A concrete wall across the river kills the run unless fish can get around it.

The Corps' primary answer was the fish ladder — a stepped series of water-filled pools at the dam's edge, designed so a fish can swim upstream through short bursts of current, resting at each pool. Bonneville, the oldest dam on the system, got the first large-scale ladder in 1937 and became the template for every subsequent project. The cover photograph shows that ladder in operation: a long concrete channel curving around the dam's powerhouse, whitewater churning through its pools.

The interior adds the other half of the equation — fish hatcheries. By 1970 the Corps and its state partners (Oregon and Washington fisheries agencies, the U.S. Fish and Wildlife Service) were intercepting adult females before they could spawn naturally, stripping and fertilizing eggs in controlled tanks, raising the young for up to fifteen months, then releasing them as fingerlings (young fish, roughly one to several inches long). The illustrated diagram contrasts this process against the natural two-to-five-year ocean life cycle side by side — a candid acknowledgment that the hatchery route substitutes for what the dams interrupted.

The pamphlet appeared at a fraught moment. The National Environmental Policy Act had just been signed on January 1, 1970, requiring federal agencies for the first time to assess environmental harm before construction — a law the Columbia-Snake dams had predated by decades. That same year, nitrogen supersaturation in the tailwater below new dams was killing smolts by the tens of thousands, forcing the Corps into emergency barge and truck transport of juvenile fish. The pamphlet's tone is confident and technical, but the fish-passage failures it was responding to were already well known to state fisheries agencies.