There are approximately 750 lakes (131 named) and about 1500 miles (2400 km) of perennial streams and rivers in Glacier National Park. The largest body of water is Lake McDonald at 10 miles (16 km) long, 1 mile (1.6 km) wide and ~464 feet (141 m) deep. St. Mary Lake is a close second. On the west side of the park the Middle and North Forks of the Flathead River delineate park boundaries and have been designated parts of the Wild and Scenic Rivers System. On the east side of the park Divide Creek forms a small portion of the park boundary.