File:The future water supply of San Francisco; a report to the Honorable the secretary of the interior and the Advisory board of engineers of the United States army (1912) (14750152466).jpg

Identifier: cu31924004975805 (find matches)
Title: The future water supply of San Francisco; a report to the Honorable the secretary of the interior and the Advisory board of engineers of the United States army
Year: 1912 (1910s)
Authors: Spring Valley water company, San Francisco
Subjects: Water-supply
Publisher: (San Francisco, Printed by the Rincon publishing company
Contributing Library: Cornell University Library
Digitizing Sponsor: MSN

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ped willbe gathered by conduits which lead to the mainconduit from Pleasanton to Sunol and thenceto San Francisco. Sunol Gravels Are Very Deep. The Sunol Underground Gravel Reservoir hasbeen briefly discussed under Storage, inthis report. Dr. Branner states that, similar to the Liv-ermore gravels, the Sunol gravels are of greatdepth. Recent borings show that these gravels arevery much deeper than Ave previously believed. So far, only approximately the upper 20 feethave been drawn upon, their function being toserve as an enormous filter through which thesurface water of the Alameda System passes,before being conveyed to San Francisco. Obviously none of the great storage lyingbelow the filter galleries, and Avhich Nature hasprovided for us, can be utilized without pump-ing. But by this method the gravels may bedepleted, and the basin serve to conserve thefloods and the surplus waters from the Calaverasand San Antonio Surface Reservoir, and theLivermore Underground Reservoir. Consequent-
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80- CONSERVATIVE YIELD OF ALAMEDA SYSTEM 135 M. G. D. 81 ly, this becomes a purely storage reservoir, fromwhich filtered water will still be drawn. Sunol Gravels Will Safely YieldOver 11 M.G.D. Plate 27 shows a mass diagram of the summa-tion of seasonal run-off of the Sunol drainage,together with the surplus water from other reser-voirs, as determined in the preceding pages ofthis report. From this diagram we see that the period oflow flow which tests the reservoir most severelyis between the seasons 1897-98 and 1905-06. With a storage of 10,000 M. G., as shown here-tofore, and starting with a full reservoirin the season of 1889-90, a safe gross yield of11.36 M. G. D. may be made upon the reservoirwith the following result: From 1889-90 to 1892-93, the draft will beslightly in excess of the inflow. From the sea-son 1892-93 to 1894-95 considerable waste willoccur each season. In the season 1895-96 thedraft and inflow are about equal. In the season1896-97 there is again waste. From the

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