High Quality Content by WIKIPEDIA articles! Jackson Lake is a lake located in north western Wyoming in Grand Teton National Park. The lake is natural, except for the top 33 feet (10 m), which is due to the construction of Jackson Lake Dam, built in 1911. This top level of the lake is utilized by farmers in Idaho for irrigation purposes. The lake is the remnant of large glacial gouging from the neighboring Teton Range, and is still fed by runoff from small glaciers near the peaks of those mountains. The main source of water is the Snake River, which flows in from the North. Jackson Lake is one of the largest high altitude lakes in the U.S. at an elevation of 6,772 feet (2,064 m) above sea level. The lake is up to 15 miles (25 km) long, 7 miles (11.25 km) wide and 438 feet (134 m) deep. The water of the lake averages below 60 degrees even during the hottest summer months and can freeze to more than 6 feet (1.8 m) thick in the winter.