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Yosemite Nature Notes - 7 - Tuolumne River

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[Music]
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Well, Yosemite National Park
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is home to these two amazing watersheds;
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the Tuolumne River watershed to the north
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and the Merced River watershed in the south fork
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of the Merced to the south.
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Those two major watersheds really do form
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the basis for the boundary of Yosemite National Park.
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We're sitting at the top of the Tuolumne River watershed,
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and basically what that means is,
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there is a drainage divide of peaks of 11,000 to 13,000 feet,
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and basically when precipitation in the form of rain
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or snow falls on this side of the drainage divide,
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it all coalesces in the form of the Tuolumne River.
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Indeed, most of the Tuolumne watershed
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kind of is a large catcher's mitt,
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with the river being fairly close
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to the southern edge of the watershed
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and having the majority of the watershed from the north.
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The Upper Tuolumne, particularly the Lyell Fork,
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is fed by two of the largest glaciers
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left on the western side of the Sierra Nevada
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and those are the Lyell and McClure Glaciers.
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The Lyell Glacier is positioned beneath Mount Lyell,
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which is the highest point in Yosemite National Park;
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it's just over 13,000 feet tall.
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And to get to the Lyell Glacier,
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it's about a 12-mile hike
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up the Lyell Fork of the Tuolumne River,
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through a big broad U-shaped Canyon,
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and then up some steep slabs,
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and then you clamber over the loose rocky moraine.
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Most of the Lyell Glacier is visible behind me here;
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the west lobe is the larger of the two.
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And we're looking at what's left really of the Lyell Glacier.
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Those glaciers have decreased dramatically
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over the last century in size and volume,
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and the concern or interest there is that
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they are the primary water source for the Lyell Fork.
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So once the snow melts off each summer,
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the flow in the Lyell Fork
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is sustained almost exclusively
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by melting of the Lyell and McClure Glacier.
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So it cascades through rest of Lyell Canyon.
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There are places where you can't even hear the river,
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you're walking right next to it
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and the water is just like glass carving its way
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through this beautiful incredible grassy meadows
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and into Tuolumne Meadows, where it's joined by the Dana Fork,
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its sister fork,
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