Flaming Gorge Reservoir, Reservoir in Sweetwater and Daggett Counties, United States.

Flaming Gorge Reservoir stretches 91 miles (146 km) between Wyoming and Utah, sitting at 6,040 feet (1,841 m) elevation within canyon country. The water winds through narrow gorges with steep rock walls and opens at some points into wide bays with gentle shorelines.

Construction of the dam began in 1958 as part of a hydroelectric project in the Colorado River Basin and was completed in 1964. Flooding transformed the gorge into a reservoir that had previously been traveled by rafters and explorers.

The reservoir lies within Flaming Gorge National Recreation Area, run by Ashley National Forest. Dutch John, Utah, was built as the dam's construction base camp and later became the administrative site. Anglers fish the Green River below the dam, whose cold water makes it a noted fly-fishing stream.

Three marinas offer boat rentals and launch ramps, with Lucerne Valley, Buckboard and Cedar Springs accessible throughout the year. Water levels fluctuate seasonally, which can affect the usability of docks and ramps.

The reservoir's bed is a narrow, steep-sided canyon of siliceous sandstone and hard quartzite layered with softer shales and siltstones. About 1.5 miles (2.4 km) east of the dam, a road cut exposes a fault scarp on the southbound side showing roughly 9 feet (3 m) of slippage.