Yosemite Nature Notes - Episode 7 - Tuolumne River


Uploaded by yosemitenationalpark on 07.12.2009

Transcript:
[Music]
Well, Yosemite National Park
is home to these two amazing watersheds;
the Tuolumne River watershed to the north
and the Merced River watershed in the south fork
of the Merced to the south.
Those two major watersheds really do form
the basis for the boundary of Yosemite National Park.
We're sitting at the top of the Tuolumne River watershed,
and basically what that means is,
there is a drainage divide of peaks of 11,000 to 13,000 feet,
and basically when precipitation in the form of rain
or snow falls on this side of the drainage divide,
it all coalesces in the form of the Tuolumne River.
Indeed, most of the Tuolumne watershed
kind of is a large catcher's mitt,
with the river being fairly close
to the southern edge of the watershed
and having the majority of the watershed from the north.
The Upper Tuolumne, particularly the Lyell Fork,
is fed by two of the largest glaciers
left on the western side of the Sierra Nevada
and those are the Lyell and McClure Glaciers.
The Lyell Glacier is positioned beneath Mount Lyell,
which is the highest point in Yosemite National Park;
it's just over 13,000 feet tall.
And to get to the Lyell Glacier,
it's about a 12-mile hike
up the Lyell Fork of the Tuolumne River,
through a big broad U-shaped Canyon,
and then up some steep slabs,
and then you clamber over the loose rocky moraine.
Most of the Lyell Glacier is visible behind me here;
the west lobe is the larger of the two.
And we're looking at what's left really of the Lyell Glacier.
Those glaciers have decreased dramatically
over the last century in size and volume,
and the concern or interest there is that
they are the primary water source for the Lyell Fork.
So once the snow melts off each summer,
the flow in the Lyell Fork
is sustained almost exclusively
by melting of the Lyell and McClure Glacier.
So it cascades through rest of Lyell Canyon.
There are places where you can't even hear the river,
you're walking right next to it
and the water is just like glass carving its way
through this beautiful incredible grassy meadows
and into Tuolumne Meadows, where it's joined by the Dana Fork,
its sister fork,
which originates off the shoulder of Mount Dana.
So these two amazing forks converge
right in Tuolumne Meadows
and they flow and meander peacefully through the landscape
until they start to tumble down
incredible granite escarpments.
Hiking down the Tuolumne River from Tuolumne Meadows
is certainly a great spring to early summer hike,
because the river just totally dominates
your experience of the place,
because it is the feature.
When you hike down that area,
it's just granite as far as the eye can see,
an amazing granite canyon that leads down to
what's known as the Grand Canyon of the Tuolumne River.
It's not a canyon as you would think of
in terms of the Grand Canyon of the Colorado,
but in terms of relief, the relief is pretty much the same,
it's about a vertical mile in the area of Pate Valley
and still 3,000-4,000 feet downstream at Poopenaut Valley,
and all the way down to Don Pedro.
The Tuolumne River drainage is one of my primary patrol areas
within Yosemite Wilderness.
We're at about 5,500 feet today in elevation,
it's a warm June day,
and very few clouds in the sky, although that may change
based upon previous days in our trip.
So one of the reasons why the lower stretches
of the Tuolumne River
are much more dramatic than the higher elevations
is because of all the side streams
that flow into the Tuolumne River.
Just along with this hike, there is Morrison Creek,
Rodgers Creek, Register Creek, Return Creek,
not to mention all of the unnamed streams
that are flowing into the river.
Some are bridged, like Return Creek and Rodgers Creek,
some you just have to take your boots off
put on your river crossing shoes for the stream crossings.
The Tuolumne River eventually
flows into Hetch Hetchy Reservoir, O'Shaughnessy Dam
collects water for millions of residents of the Bay Area.
Well, the City of San Francisco is certainly interested
in the Tuolumne watersheds starting in the 1880s.
They recognized this one as delivering
particularly good water
that was already protected within the National Park.
In 1913, the Raker Act was passed
and that permitted the City
to construct two reservoirs in the park;
the first one being Lake Eleanor
and then ultimately the construction of
Hetch Hetchy Reservoir and O'Shaughnessy Dam
completed first in 1923
and then raised and completed again in 1938.
It was a valley that many compared to
Yosemite Valley itself
and no one would think today of putting a dam
on the Merced River and damming Yosemite Valley.
You know, one of the lessons learned from Hetch Hetchy
was that dams in a national park,
where we are preserving these resources
for future generations,
that typically dams just don't belong here.
The dam on the Tuolumne River at Hetch Hetchy,
I think in a lot of ways ensured that
dams on other rivers might not happen.
The river ultimately benefits millions of people,
there is certainly three to four million people
visiting Yosemite National Park,
and a fair proportion of them of course
come to Tuolumne Meadows
and experience the river in its natural state,
but then several million more are benefiting from the river,
because of its water supply delivered
to the Bay Area residents.
I think about the river coming right off of that glacier and
knowing what the river turns into and what it means to
so many people who come here and enjoy it.
You know, looking at this canyon and how huge it is
and the amount of water coming down this river,
it makes you feel small,
and I think that's one of the reasons
why people come to places like this,
is that it kind of puts things in perspective for them.
This has been a place where people come back to
for thousands and thousands of years,
it draws people back,
and if you come and dip your toes in the water,
it will draw you back too.