Water Supply of San Francisco
The proposed Hetch Hetchy water supply plan for San Francisco, Cal., as voted on January 10, 1910, and which is now in progress of construction, will cost, it is estimated, in the neighborhood of $45,000,000. The supply will include water from the Tuolumne River and Lake Eleanor, and will eventually amount to some 400,000,000 gallons daily, half of which will go to San Francisco and the other to East Bay cities and San Jose, including the small communities of the Metropolitan District. The initial development is to provide 133,000,000 gallons daily for the use of the Metropolitan District and 67,000,000 gallons for San Francisco. The latest report on the status of the project describes the work done as follows: A railroad 68 miles long has been built from Hetch Hetchy Junction, on the Sierra Railway, 26 miles northeast of Oakdale, to Hetch Hetchy Damsite, at a cost of approximately $2,000,000. A 4,000-HP. hydro-electric power plant has been completed at Early Intake, 12 miles below Hetch Hetchy, which provides electricity for all the construction operations in the mountains. A buttressed arch dam at Lake Eleanor, 64 feet high and 1,200 feet long, has been constructed across the gorge one mile below the lake, which now has a capacity of double the size of Lake Chabot. A power canal in tunnel aqueduct and in flume, 3 miles long, has been built from Cherry River to the power plant. This canal is fed in low periods of water flow by the released water from Lake Eleanor. A power line has been built from Early Intake to Priest, a length of about 20 miles, and electricity is now conducted into all of the larger headings of the tunnel aqueduct, for lighting and construction use. The main tunnel aqueduct has been started from Early Intake to Priest. This tunnel aqueduct will be 10 feet 3 inches in diameter, lined smoothly with concrete, capable of carrying 400,000,000 gallons of water per day. Explorations and preparations have been made for construction of a large dam at Hetch Hetchy, and a low forebay dam at Priest, which will carry three days’ flow of the aqueduct. The Hetch Hetchy dam will be 320 feet above the water surface in the stream and an average of 65 feet below and will store 112,400.000 gallons of water over a territory covering nearly 1,930 acres. A future larger dam at Lake Eleanor will be able to store 93,000,000 gallons of water in a reservoir of 1,143 acres. Generally, all the more difficult portions of the work in the inaccessible mountains have been well started, and money may be spent now at the rate of $6,000,000 per year to complete the project. If this is done, water could be delivered to San Francisco inside of six years.
The preliminary work, when completed, will include: 1. Low dam at Hetch Hetchy; 2. Nineteen miles of 400,000,000 gallons daily capacity pressure aqueduct, 10 feet 3 inches in diameter, with 8 feet fall per mile, from a point at Early Intake, 12 miles below Hetch Hetchy, to Priest reservoir, where a power drop of 1,300 feet would create 66,000 mechanical horsepower; 3. Power drop to Moccasin Creek; 4. Seventeen and one-half miles of 400,000,000 gallons daily capacity aqueduct tunnel, 10 feet 3 inches diameter, from Moccasin Creek to east side San Joaquin Valley; 5. Forty-five miles of 6 feet 10 inch diameter steel pipe across San Joaquin Valley, 133,000,000 gallons daily caapacity; 6. Thirtyone-and one-half miles of 10 feet tunnel through Diablo range to Irvington, 200,000,000 gallons daily capacity; 7. Thirty-one and one-half miles of pipe 6 feet 4 inches in diameter, capacity 67,000,000 gallons daily, and 20 1/2 miles of tunnel, 200,000,000 gallons daily capacity, to San Francisco, making a total length of 156 miles.
The above-described work is being carried out under the direction of M. M. O’Shauglmessy, City Engineer of San Francisco.