One Hundred Year Flood

Fifteen years ago, in the winter of 1996-97, Yosemite Valley had a 100-year flood, and the damage was great enough to the road and the infrastructure that the valley was closed for months.  When I could get in, I hiked the length of the valley, from the east end to the west, surveying the damage.

The bridge crossing Tenaya Creek above Mirror Meadow is down, washed away like most of the other footbridges in this area.  I reach the other side by stepping across boulders in the stream.  The trail that went along the river bank is gone.

In many places the water is red-orange, indicating the presence of iron.  There is an actual "Iron Spring" below the lower pool of Mirror Lake that colors the water there, but this coloring is new since the flood and starts just below where Snow Creek joins in.  The pine trees in the middle section of Tenaya's landscape are dying out, whether this is due to the change in the river's route, damage from the flood, the new presence of iron in the water, an infestation of insects made possible by the environmental changes, or all of the above.  It's an example of how changing one element in nature creates a ripple effect throughout the ecosystem.

The new stream route flows over clean, white granite.  The accumulated detritus of decades, as well as the soil that built up over the years, have been swept away by the flood.  Trees that used to line the river bank now stand in the middle of a beach of white granite sand.

The riverbed going into Mirror Meadow has been altered from a quiet, pastoral scene to something that resembles the torn-up delta below Yosemite Falls.  Furrows have been dug through its broad plain, and boulders line the new river banks, pushed to the side by the surging water.  Footbridges that managed to stay intact now have no trails leading to them or from.

Below Mirror Meadow the river bank eroded away to such an extent that the main metal footbridge across collapsed into the flood and was swept away.  At this end of the valley, the flood took shortcuts over bends in the river and swept away the Upper and Lower River Campgrounds.

In the middle of the valley, the meadows are buried under a foot of granite sand and look like a wasteland.  The place on the river bank where I used to sit and listen to the water ouzel play in the water and watch the colors of the sunset spread across the sky are gone.  The cabins below the Lodge were destroyed.

At the Cathedral beach area down by El Capitan, the flood shifted the river 150 feet away, leaving a massive gravel sandbar behind.  On the bend, a large section of the forest was eroded away by the power of the water, and trees were tossed into the woods like unwanted toys.

At Valley View in the west end, where the canyon walls come together and the river leaves the valley, the rushing water compressed.  Everything being carried along in the water battered the trunks of the trees, taking out chunks of bark.  Further down the canyon, the river washed out the river road.