Hells Canyon Dam is a concrete gravity dam in the western United States, on the Snake River in Hells Canyon along the Idaho-Oregon border. At river mile 247, the dam impounds Hells Canyon Reservoir; its spillway elevation is 1,680 feet (512 m) above sea level.

The Snake River is a major river in the interior Pacific Northwest region of the United States. About 1,080 miles (1,740 km) long, it is the largest tributary of the Columbia River, which is the largest North American river that empties into the Pacific Ocean. Beginning in Yellowstone National Park, western Wyoming, it flows across the arid Snake River Plain of southern Idaho, the rugged Hells Canyon on the borders of Idaho, Oregon and Washington, and finally the rolling Palouse Hills of southeast Washington. It joins the Columbia River just downstream from the Tri-Cities, Washington, in the southern Columbia Basin.