<P> As the Bonneville Floods rushed down the Snake River, the Missoula Floods occurred in the same period, but farther north . The Missoula Floods, which took place more than 40 times in the time span from 15,000 to 13,000 years ago, were caused by Glacial Lake Missoula on the Clark Fork repeatedly being impounded by ice dams then breaking through, with the lake's water rushing over much of eastern Washington in massive surges far larger than the Lake Bonneville Flood . These floods pooled behind the Cascade Range into enormous lakes and spilled over the northern drainage divide of the Snake River watershed, carving deep canyons through the Palouse Hills . The Palouse River canyon was the largest of the many gorges cut through the Palouse Hills, and could not have become as large as it now is if it were not for the Missoula Floods . The Lake Bonneville Floods and the Missoula Floods helped widen and deepen the Columbia River Gorge, a giant water gap which allows water from the Columbia and Snake rivers to take a direct route through the Cascade Range to the Pacific . </P> <P> The massive amounts of sediment deposited by the Lake Bonneville Floods in the Snake River Plain also had a lasting effect on most of the middle Snake River . The high hydraulic conductivity of the mostly - basalt rocks in the plain led to the formation of the Snake River Aquifer, one of the most productive aquifers in North America . Many rivers and streams flowing from the north side of the plain sink into the aquifer instead of flowing into the Snake River, a group of watersheds called the lost streams of Idaho . The aquifer filled to hold nearly 100,000,000 acre feet (120 km) of water, underlying about 10,000 square miles (26,000 km) in a plume 1,300 feet (400 m) thick . In places, water exits from rivers at rates of nearly 600 cubic feet per second (17 m / s). Much of the water lost by the Snake River as it transects the plain issues back into the river at its western end, by way of many artesian springs . </P> <P> The Snake River is the thirteenth longest river in the United States . Its watershed is the 10th largest among North American rivers, and covers almost 108,000 square miles (280,000 km) in portions of six U.S. states: Wyoming, Idaho, Nevada, Utah, Oregon, and Washington, with the largest portion in Idaho . Most of the Snake River watershed lies between the Rocky Mountains on the east and the Columbia Plateau on the northwest . The largest tributary of the Columbia River, the Snake River watershed makes up about 41% of the entire Columbia River Basin . Its average discharge at the mouth constitutes 31% of the Columbia's flow at that point . Above the confluence, the Snake is slightly longer than the Columbia--1,078 miles (1,735 km) compared to 928 miles (1,493 km)--and its drainage basin is slightly larger--4% bigger than the upstream Columbia River watershed . </P> <P> The mostly semi-arid, even desert climate of the Snake River watershed on average, receives less than 12 inches (300 mm) of precipitation per year . However, precipitation in the Snake River watershed varies widely . At Twin Falls, in the center of the Snake River Plain, the climate is nearly desert, with an annual rainfall of just 9.24 inches (235 mm), although the average snowfall is 13.1 inches (330 mm). This desert climate occupies the majority of the basin of the Snake River, so although it is longer than the Columbia River above the Tri-Cities, its discharge is on average significantly less . However, in the high Rockies of Wyoming, in the upper Jackson Hole area, the average precipitation is over 30 inches (760 mm), and snowfall averages 252 inches (6,400 mm). Most of the Snake River basin consists of wide, arid plains and rolling hills, bordered by high mountains . In the upper parts of the watershed, however, the river flows through an area with a distinct alpine climate . There are also stretches where the river and its tributaries have incised themselves into tight gorges . The Snake River watershed includes parts of Yellowstone National Park, Grand Teton National Park, Hells Canyon National Recreation Area, and many other national and state parks . </P>

Does the snake river flow into the columbia river