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|Yellowstone National Park (9)|
Yellowstone and Other Lakes
Yellowstone Lake One of the most exceptional features of the park is Yellowstone Lake, located in the central portion of the park. Yellowstone Lake is extremely large, covering 136 square miles. It is in fact the largest lake in the world at its elevation, which is 7,733 feet, and one of the largest 100 lakes anywhere. It is so large that the lake actually creates its own weather. The lake also contains 7 named islands.
The size of the lake is very impressive. It is approximately 20 x 14 miles, with more than 110 miles of shoreline, much of which is rocky and wilderness. It fills part of the caldera which resulted from the catastrophic eruption, filling in the basin in the southeast part of the caldera between the caldera's east rim and flows of rhyolite on the west. As the caldera floor rose it caused the lake to backfill the old river canyon which ran across the rim. The magma chamber beneath this art of Yellowstone continues to cause the caldera floor to rise 1 inch per year, and may on occasion trigger earthquakes.
The lake is quite deep as well, averaging 137-139 feet and reaching 339-430 feet at its deepest point. It takes about 10 or 11 years for all of the water in the lake to completely replace itself.
The water in the lake is very cold and clear. The water at the bottom of the lake remains a chilly 42 degrees year around. However, explorations of the lake bottom have revealed vents spouting boiling water and deep fissures there.
Yellowstone Lake, as large as it is presently, was in ancient times more than twice its present size. 10,000 years ago the lake was 270 feet higher when glaciers dammed the river downstream. It is currently fed by 125 tributary streams.
Yellowstone Lake is famous for its cutthroat trout fishing. Cutthrout trout, named for the red slash visible under their gills, are one of two native fish in the park, which also includes Arctic greyling. In addition to fishing, commercial boating on the lake was begun in 1889.
Yellowstone Lake freezes over in the winter. Ice begins to form in October, but December 25 is the "average" day when the lake is completely frozen over. In winter, the ice which covers the lake may average 3 feet thick. This ice has generally completely disappeared sometime between May 16 and June 11. The fishing season on the lake begins on June 15.
Water flows out of Yellowstone Lake into the Yellowstone River through the Grand Canyon of the Yellowstone to the north. It joins the Missouri River, then the Mississippi, and eventually ends up in the Gulf of Mexico.
The West Thumb section of Yellowstone Lake fills in the collapsed caldera of a crater from an eruption 150-200,000 years ago, subsequent to the great Yellowstone eruption. As such it is the deepest part of Yellowstone Lake. Its name comes from the fact that early explorers of the area felt that the lake resembled an outstretched hand, and this section of the lake looked like the thumb of that hand. The section is closed enough from the rest of the lake that it is almost a separate lake.
Other Lakes Yellowstone Lake is by far the largest body of water in he park but there are also more than 200 lakes. Isa Lake, named after a Cincinnati tourist and shown below, is a small but unique body of water. It sits directly on the Continental Divide at an altitude of 8,261 feet, and the water in the lake may drain via one of two outlets, one which leads to the Atlantic Ocean or another which leads to the Pacific Ocean. It is sometimes called "Two Ocean Lake."
A divide is a topographic boundary which divides adjacent drainage basins or watersheds. The Continental Divide, a major feature of the American west, meanders through the park.
Shoshone Lake is found in the extreme southern section of the park. In the picture below, taken from the vicinity of Shoshone Point, it can be seen just above the center of the picture. Shoshone Lake is the second largest lake in the park, and is the largest lake in the lower 48 states without road access. The Grand Tetons can also be seen to the south from Shoshone Point. Water from Shoshone Lake drains to the Pacific Ocean through the Snake River system to the south. There is also a geyser basin on the shore of the lake.
Lewis Lake is the third largest lake in Yellowstone National Park. It is 108 feet deep. It is actually connected to Shoshone Lake (above) by a narrow channel. Its water thus also drains to the Pacific via the Snake River. Like Shoshone Lake, Lewis Lake fills basins formed between adjacent flows of lava from a volcanic eruption.
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