RESERVOIRS AND DAMS.
STORAGE RESERVOIRS.
Sources of Water-Supply.—Running
streams, melting snows and rains are the sources from which the
mining districts derive their water-supply. The altitudes of the
gravel deposits, two hundred to fifty-five hundred feet above the
sea-level, necessitate the bringing of the water from still greater
elevations nearer the sources of the streams. The supply from these
streams is not always sufficient. Towards the end of winter and during
the spring months, while the mountains are still covered with deep
snow, rains and temperate weather cause sudden and rapid thawing, and
enormous volumes of water are then discharged from the many water-sheds
on the west flank of the Sierra Nevada into the Great Valley of
California, and freshets are of quite common occurrence. To make this
supply of water available, storage reservoirs have been constructed by
some of the large hydraulic-mining companies.
The dry season in California is from May to November, but the streams do not run dry until the middle of June or July.
Requirements for Sites.—The
principal storage reservoirs in the State are situated at elevations of
five thousand to seven thousand feet above the sea-level. The location
of a proper site for a storage reservoir is of paramount importance.
In selecting a site especial attention must be paid to the following
points:
(i) A proper elevation.
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