The U.S. Army Corps of Engineers spent $7 million on fish ladders in 1938 to move salmon past Bonneville Dam; decades later, the system carries 1 million a season in good years

Think about the expansion of a construction budget of nearly 1,000 percent, not for some stadium or high-rise building but for the creation of a set of fish ladders. This is the scenario that occurred with Bonneville Dam, on the Columbia River near the Oregon and Washington state border. The U.S. Army Corps of Engineers had a $640,000 budget for "fishways" to allow migrating salmon to swim through the new dam. The actual expenses exceeded $7 million, an astonishing figure during the Great Depression era, as a result of public pressure forcing one engineer to redo their design. According to the historical records by the Northwest Power and Conservation Council, the fishways became much more complex and expensive than initially expected.

However, by 1937, while the rest of the project was still being finished, the fishway was already working. That year, the annual report of the U.S. Commissioner of Fisheries noted that salmon were climbing the Bonneville fish ladder with far less effort than expected. Nearly 90 years have passed since then, and that over-engineered structure is still working as it should. The U.S. Army Corps of Engineers has counted every adult salmon and steelhead passing the Bonneville ladders since 1938, and in a strong year the total can exceed 1 million fish, with some counts topping 1.5 million, a sharp contrast to the zero fish passage a dam with no ladders would have allowed.

A new deal fix that actually held up


Bonneville was one of the star projects of President Franklin D. Roosevelt’s New Deal, and it was constructed to provide the people of the Pacific Northwest region with cheap hydroelectricity. Passage for fish was not something added to the dam at a later date; the planners of the Bonneville Dam knew that without some assistance, such a dam in that region would simply wipe out all the salmon from that stretch of the river.

Therefore, they built the ladders, a series of pools allowing the fish to climb past the dam. The truly amazing thing is that this 1930s technology built with slide rule and without any previous examples of success is still the backbone of fish passage on one of North America's biggest rivers.

"About a million fish" isn't the whole scoreboard

This is where it might be wise to stop and reflect upon the significance of the Bonneville count before calling it a success story. A meaningful share of the fish passing Bonneville today are of hatchery origin rather than wild-born, since the 1930s and '40s, federal programs (including the 1938 Mitchell Act) have funded hatcheries throughout the lower Columbia specifically to supplement runs affected by dam-building, and annual federal funding for those hatcheries has run $12 million to $22 million in recent years. The picture gets harder the further upstream you look. Bonneville's count reflects fish reaching the lower river; the Snake River basin, which drains into the Columbia well upstream of Bonneville, tells a starker story about what's happening to wild fish once they're past it.

According to NOAA Fisheries' latest five-year status review reports, certain wild salmon and steelhead populations from the interior Columbia and Snake River basins (upstream of Bonneville) are still listed under the Endangered Species Act. Several of those populations have seen a dramatic decrease in numbers close to 50 percent in the past five years due to poor ocean survival and climate change effects. If we look at it from a broader perspective, the situation becomes even more dire. According to an official policy statement from the American Fisheries Society, about 1 to 2 percent of the historical number of wild salmon and steelhead migrate back to spawn in the Snake River basin, which sits above the four lower Snake River dams. It is a region that used to hold about half of all the Chinook and steelhead population in the Columbia Basin.

Why this matters beyond Oregon

Bonneville’s fish ladders are an odd success story: a public works program that took into account its environmental cost from the beginning, suffered a huge overrun, and is still going strong decades later. Yet the fact that one million fish now pass through Bonneville’s ladders each year, by itself, glosses over a system that is relying on hatcheries to cover its continued failure upstream.

This is "problem managed, very expensively, forever.” This isn't to say that fish ladders were doomed to fail, but that trying to fix the problem at one dam in no way negates all the damage that has been done by a whole river system of dams, ocean temperature rise, and habitat destruction.