Bonneville Dam Powerhouse

Bonneville Dam is the last spillway the Columbia sees before emptying into the Pacific. The river is under tidal influence until around Camas, though the salt water doesn't intrude nearly that far.

This is the first powerhouse, finished in 1937. A second, which replaced a weir across to the Washington State bank, was completed in 1981. The turbines have only 50ft of hydraulic head to work with, which required a number of design compromises.

In total, the 18 turbines of the dam can produce 1092MW. To compare, the Trojan nuclear plant that was sited downstream was rated for similar power from a single reactor.