Which reservoir was formed by Glen Canyon Dam?

The reservoir formed by Glen Canyon Dam is Lake Powell.

Lake Powell lies on the Colorado River in northern Arizona and southern Utah. Glen Canyon Dam, built near Page, Arizona, blocks the river and backs water up through the former Glen Canyon and its side canyons. The resulting reservoir is one of the largest artificial lakes in the United States.

Construction began in 1956, and the dam was completed in 1966. The reservoir gradually filled and first reached full-pool level in 1980. It stores water for the Upper Colorado River Basin states and helps regulate deliveries to the Lower Basin, while the dam’s turbines generate hydroelectric power.

Lake Powell is named for John Wesley Powell, who led an 1869 expedition down the Colorado River. It is often confused with Lake Mead, another major Colorado River reservoir downstream. Lake Mead is held behind Hoover Dam; Lake Powell is held behind Glen Canyon Dam.