Central California - May/June 2009

Yosemite National Park - Hetch Hetchy Reservoir

Hetch Hetchy Reservoir is located in the northern part of Yosemite NP. Completed in 1923, the reservoir supplies 80+% of San Francisco's drinking water via the Hetch Hetchy Aqueduct. The water is not filtered, so boating and swimming are prohibited. Fishing is allowed, but only from the shoreline.

The Hetch Hetchy Valley, which the reservoir claimed, was at one time as beautiful as Yosemite Valley. In fact, this is the only reservoir built on National Park lands. John Muir, a naturalist and contemporary of Ansel Adams, fought bitterly against the construction of the dam and reservoir. And to this day there are groups fighting to remove the dam and restore the valley to its natural state. But at  $10+ billion to remove the dam and construct replacement water resources, I doubt things will change anytime soon.

	The reservoir from an overlook along Hetch Hetchy Road. Here we see O'Shaughnessy Dam and a lower cascade of Wapama Falls.
	They were dumping a lot water out of the reservoir, I have to assume due to the spring thaw. Here we see the discharge from the face of the dam. Note the small amount of water flowing along the rocks just right of center. This is a spillway discharge channel. The spillway gates were nearly closed, I assume being held in reserve in case more discharge is required.
	Another shot of the discharge from the dam face. This time-exposure was taken with the ND3.0 filter. Note the gap in the rocks near the bottom of the image. This is the spillway channel. While it may not look it, this gap is about 20ft wide. Also note at the far end of the dam there is a tunnel. This allows access the several hiking trails on the north side of the reservoir.
	Another discharge just downstream from the base of the dam. Here the water flows out of a large conduit and sprays across the Tuolumne River, rebounding off the rocks on the opposite side. The volume of water flowing was truly amazing. I have to wonder how this has eroded the rocks over time, and how long that cliff face will last.
	A closer shot of the lower cascade of Wapama Falls. There must be more to these falls since several sources list their height at around 1300ft. The falls we see here is nowhere near that high, maybe 200ft max. The rest of the cascades must be hidden here in the indentation of the cliff.

	San Francisco Yosemite Valley Yosemite Waterfalls Hetch Hetchy Reservoir Tioga Pass Road 1 Tioga Pass Road 2 Mammoth Lakes – Fire… Mammoth Lakes – ... and Ice South on US395 Moonrise at the Golden Gate
<Prev	Central California 2008 Home	Next>
	alhann.com
All images copyright ©2009 by Al Hann All rights reserved