New Don Pedro Dam
| New Don Pedro Dam | |||||||||
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| Coordinates | 37 ° 42 ′ 3 ″ N , 120 ° 25 ′ 15 ″ W | ||||||||
| Data on the structure | |||||||||
| Construction time: | 1967-1971 | ||||||||
| Height of the barrier structure : | 178 m | ||||||||
| Building volume: | 12 million m³ | ||||||||
| Crown length: | 853 m | ||||||||
| Base width: | 579 m | ||||||||
| Power plant output: | 203 MW | ||||||||
| Data on the reservoir | |||||||||
| Altitude (at congestion destination ) | approx. 253 m | ||||||||
| Water surface | 53 km² | ||||||||
| Storage space | 2504 (2835) million m³ | ||||||||
| Catchment area | 3900 km² | ||||||||
The New Don Pedro Dam ( English Lake Don Pedro, Don Pedro Lake, Don Pedro Reservoir or "Don Pedro Dam") on the Tuolumne River is the fifth largest dam in California . The town of Moccasin is located near the reservoir .
In addition to the new, larger Don Pedro Dam with a rock embankment dam , which was built in 1971, there is also the old dam from 1923 with the Old Don Pedro Dam, a dam wall that is normally dammed.
The reservoir
The reservoir lies at the foot of the Sierra Nevada . It has about 260 kilometers of shoreline, about 42 km of the course of the Tuolumne River, and a water surface of 53 km². The storage space of around 2.5 km³ is fed by a catchment area of 3900 km² . The water is used by the Modesto Irrigation District (MID) and the Turlock Irrigation District (TID) to irrigate many hundreds of square kilometers of agricultural land in the fertile Central Valley . After treatment, some of the water from the MID is also used as drinking water for Modesto . The two irrigation districts and the United States Bureau of Land Management (BLM) own the land to a height of 4.5 meters above the highest water level; therefore there are no private jetties on lake properties. There are only three public access points to the water.
The five largest reservoirs in California, measured by storage space, are:
- 5.61 km³ Lake Shasta
- 4.37 km³ Lake Oroville
- 3.02 km³ Trinity Lake
- 2.99 km³ New Melones Lake
- 2.50 km³ New Don Pedro (corresponds to 2504 million m³; the number is also given as 2835 million)
Because Don Pedro Lake is not part of the Hetch Hetchy Water and Power System , water from this network flows through tunnels under the top of the reservoir. Lake Don Pedro could easily be included in this network, and the efforts of the Restore-Hetch-Hetchy Group to drain the reservoir in the Hetch Hetchy Valley are hopeful for this possibility. The San Francisco Public Utilities Commission (SFPUC), of which Hetch Hetchy Water and Power is a division, has borne 45 percent of the construction costs of the new Don Pedro Dam and therefore has the right to store 0.7 km³ of water in it. However, the rights of the MID and TID are older than those of the SFPUC, and therefore they can use up the stored water for their own purposes in dry periods.
The New Don Pedro Dam
The new New Don Pedro Dam is a 178 meter high earth and stone rubble dam. It is 853 meters long and 579 meters wide at its base. It has a volume of 12 million cubic meters of bulk material, much of which comes from old gold panning heaps on the Tuolumne near La Grange . Construction began in September 1967, the dam was finished on May 28, 1970 and the inauguration was on May 22, 1971. While the TID operates the hydropower plant at the foot of the dam, the MID owns 31.54 percent of the power plant and is therefore allowed to 63 of the 203 Megawatts produced by four generators . The water that leaves the power plant flows four kilometers downstream to the La Grange Dam, where much of it is diverted into irrigation canals. The remainder flows the 84 kilometers to the confluence with the San Joaquin River .
The old dam (Old Don Pedro Dam)
The original Don Pedro Dam, known as the Old Don Pedro Dam since 1971 , is an 86 meter high gravity dam , 305 meters long, five meters at the top and 52 meters wide at the base. It was completed in 1923 at a point (coordinates: 37.7125 N, 120.4020 W) where the Tuolumne River had dug a narrow gorge into the rock, about two kilometers below Don Pedro Bar. The old Lake contained Don Pedro up to 0.358 km³ of water, 14.3 percent of today's capacity. There was only one 15 kilowatt power station, and two more 7.5 kW generators were added in 1926, making the total 30 kilowatts. That is 0.015 percent of today's capacity. The old dam is 2.5 kilometers above the new dam, and because the old wall crown is only 177 meters above sea level, it is now about 76 meters under water when the reservoir is full. A report on the construction of The First Don Pedro is available on the MID website.
See also
- List of the largest dams on earth
- List of the largest reservoirs on earth
- List of the largest hydroelectric plants in the world
- List of dams in the world
Web links
- New Don Pedro Dam in the United States Geological Survey's Geographic Names Information System
- Don Pedro Reservoir in the United States Geological Survey's Geographic Names Information System
- Turlock Irrigation District
- Modesto Irrigation District
- SFPUC: Hetch Hetchy Water and Power ( Memento from August 24, 2005 in the Internet Archive )
- USGS Hydrologic Data
- Lessons from Hetch Hetchy by Richard W. Amero ( Memento from June 30, 2007 in the Internet Archive )
- www.donpedrolake.com
- The First Don Pedro
- Restore Hetch Hetchy