Scientists use radio transmiters to track smolts as they pass through the McNary Dam.

When Lewis and Clark explored the West 200 years ago, they recorded that the salmon were "jumping verry thick." Back then, 10 to 15 million salmon returned from the ocean each year to spawn in the Columbia-Snake river system, which stretches across four states and up into Canada. The system alone was once home to hundreds of distinct stocks of salmon, each one adapted to use it in its own way. Now throughout the entire West Coast only 56 stocks remain, and 26 of those are officially endangered.

Beginning in the 19th Century, overfishing, logging and dam building decimated the Pacific Northwest's natural salmon populations. In "Out West - Conquering the Columbia," Alan meets engineers and biologists seeking to save the wild salmon before it's too late.

Today, the Columbia-Snake river system contains hundreds of dams, several of which completely block fish from going upstream, knocking out more than a third of the system's original salmon habitat. The dams make life much harder for salmon in other ways, too. Young fish heading out to sea must make it through generator turbines and over spillways. They have to dodge predators in the wide-open reservoirs, where they also must use precious energy to swim through the slow-moving water. Those that make it out to sea and back have more troubles to contend with upon their return -- spawning streams damaged or destroyed by logging, or flooded behind dams.

Logging, canning and dams pose challenges for the once abundant Pacific salmon.

Alan visits the Army Corps of Engineers' McNary dam, opened in 1953. Its 14 turbines can generate 980 megawatts of electricity. In recent years the Corps has been looking for ways to reduce the impact on salmon of all their Columbia-Snake River dams. Biologists determined that about 90% of young fish can survive if a turbine is run somewhat below its maximum output. Researchers show Alan how a 6-inch-long young salmon can enter a huge spinning turbine, to emerge on the other side unscathed. Engineers have designed elaborate and expensive screen systems that catch the young fish and direct them around turbines. McNary Dam has 42 such screens, at a cost of $18 million. Around half the young fish in the system even get a free ride down river in barges, courtesy the Army Corps of Engineers.

Yet after more than a hundred years of river-stocking with hatcheries, decades of research, and 15 years running the dams with fish in mind, it's still not clear if wild salmon are going to make it in the Columbia.

For more on this topic, see the web feature:
Fishy Figures
Who Owns the Sea?