Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay
|Above: panorama of the Tuolumne River Canyon.
Left and below: the Tuolumne River Canyon below Hetch Hetchy Valley.
|Left and below: Scenes on the Hetch Hetchy road.|
|Left and below: Tuolumne River Canyon just below the dam.|
|Left and below: O'Shaugnessy Dam. The dam was built to supply water to San Francisco. The dam is small and not easily visible from even a short distance away. That's the idea. A dam is supposed to be small.|
|So why wasn't the dam built at the narrow gorge in the distance? Probably because a low dam would have backed water up only a short distance and a dam capable of impounding a large volume of water would have been very high. Note that the actual dam above is resting on a quite high bedrock step and the valley drops steeply below the dam.|
Construction of the dam and flooding of the reservoir was a bitter defeat for California conservationists in the 1920's, but I really can't look at this and see an environmental disaster. The watershed is well protected and there is no boating and fishing in the lake (the boat belongs to the water authority.)
|Left and below: O' Shaugnessy Dam.|
|A tunnel beyond the dam leads to hiking trails|
|Granodiorite intruded by dikes.|
|Insignia of the water authority.|
|This is bear country. You can drive here but anyone camping here needs a wilderness permit. And food must be stored in bear-proof containers (cars are emphatically not bear-proof).|
Created 14 July 2003, Last Update 07 June 2020