John Day Dam!

The John Day Dam is a major structure on the Columbia River, located at river mile 215.6, about 28 miles (45 km) east of The Dalles, Oregon, and just below the mouth of the John Day River. It spans the river between Sherman County, Oregon, and Klickitat County, Washington. Operated by the U.S. Army Corps of Engineers, this concrete gravity run-of-the-river dam was completed in 1971 after construction began in 1958, at a cost of $511 million. It’s part of the Columbia River Basin dam system, designed primarily for hydroelectric power and navigation.
Here’s what stands out about it:
Power Generation: It has 16 turbine units with a nameplate capacity of 2,160 megawatts and an overload capacity of 2,485 megawatts—enough to power roughly two cities the size of Seattle. Skeleton units for four more generators were built in, hinting at potential expansion.
Navigation Lock: The John Day Lock boasts the highest lift of any U.S. lock at 110 feet (34 meters), allowing barges and ships to navigate the river’s elevation changes.
Reservoir: The dam forms Lake Umatilla, stretching 76.4 miles (123 km) upstream to the McNary Dam. The reservoir’s full pool elevation is 268 feet (82 meters), with a usable storage capacity of 534,000 acre-feet between 257 and 268 feet.
Fish Passage: It includes fish ladders on both sides to aid salmon and steelhead migration, though the 76-mile reservoir has been noted as a tough stretch for young salmon, with high mortality rates reported in studies from the mid-2000s.
The dam’s not open to the public for tours, but you can get a good view from Giles French Park downstream. It’s a powerhouse—literally and figuratively—but its impact on the river’s ecology, especially salmon runs, has long been debated.