WATER SUPPLY OF SAN JOSE CAL.
THE principal source of water supply of San Jose. Cal., is found in various mountain streams, fed by strong springs well up on the sides of the Santa Cruz mountains. The main stream is on Los Gatos creek, which has its source on the western slope of Loma Prieta, the highest peak of the hills, visible far out at sea and a most conspicuous object from all portions of Santa Clara valley and from the elevations of the coast range, from Mount Diablo southwards for many miles. From the eastern and southeastern slopes of this peak the I.lagas and Uvas creeks arise and flow southeasterly, entering the ocean at last through the Pajaro river.
The main dam by which the waters of this creek are diverted is situated between Alma and Wrights, and a flume, carried along the sides of the Los Gatoscanyon, conveys the water to the first reservoir, situated on the heights above the city of Los Gatos. This flume is covered, and some parts of the original structure have been replaced with iron pipe, twenty-eight inches in diameter, in places where this conduit appears to be of advantage. About three miles above Alma, towards the west, and at an elevation of something like 1 400 feet above the sea, a site was found where it was comparatively easy to construct two reservoirs, having an area of over thirty acres; and to these the waters of a fine stream are conducted in winter, which fills the storage basins.
Whcn these reservoirs are filled by the winter flow, the more moderate spring and summer supply just about makes good the loss by evaporation until July or August, when the gates are opened and the escaping water goes tumbling down the rocky and gravely bed of a mountain stream for a couple of miles, dashing over cascades in foam and spray, and filtering through beds of clean washed gravel, when it is gathered into a large iron pipe and carried, pure from its aeration and filtering, to the main flume running along the canyon
Still farther up the mountain is situated the Lake Ranch reservoir, of some thirty-six acres, whose two dams retain a hotly of water of about 150,000 000 gallons. This is utilized in the same manner as is the water of the twin reservoirs, only the natural channel is longer before it is gathered up and piped into ‘he great main.
In order to utilize this water still further, it is being piped into a gravel leservoir, through which it is filtered—thus furnishing pure, clear water in winter when the main stream may be temporarily roiled by a great storm. Another side stream furnishes an abundant flow of clear water on like occasions in winter Another impounding reservoir is being constructed, fir up, near the head ot the main stream, above Wrights, where will be stored an additional supply that would otherwise go to waste. This reservoir will have the same capacity as the Lake Ranch reservoir, and on the same tract, owned by the company, are two additional sites of equal capacity. Water has been stored in, and used from this reservoir for the past two years, with increased capacity each year.
The water from the Los Gatos reservoir is conducted through an iron conduit and gives about 200 feet of pressure, to turn the wheels of the Los Gatos ice factory—thus being again aerated in the most perfect manner. As the water leaves these wheels, which run night and day, it is piped into the Seven Mile reservoir, having a capacity of 7.5110,000 gallons. Here it settles and deposits any sediment which it may have carried down the mountain, and it is then conducted down the Cambrian reservoir, which is the main distributing reservoir of the city of San Jose. From this point it is carried in two lines of pipe, entering San Jose at its highest southern point, and making almost a complete circuit of the city. Retween the last named reservoir and San Jose is located an extensive pumping plant from deep wells, which may be used in case of emergency; but so far this plant has been confined only to periodical trials to prove that it is in working order. At each of the reservoirs a trusty man is stationed, on the alert night and day, to see that all is well. If a storm arises and muddy water makes its appearance, it is not allowed to enter. Waste weirs are watched and supply and delivery gates adjusted to the circumstances. A telephone wire connects the San Jose office with all the men in charge of reservoirs, so that they are in constant communication with the superintendent. To guard against accident the company has constructed a pumping plant, having a capacity larger than the demands of the city of San Jose. That, as is well known, lies within the artesian bel’, and there are several underlying strata bearing abundant water. The water company owns a rather broad strip of land bordering on the creek on which it has bored twelve artesian wells of various depths from 180 to 1,180 feet, so as to tap the various underlying water courses.
Each of these wells forces water slightly above the surface; but all are connected by large pipes which centre in an immense cistern, fifty feet in depth and twenty feet in diameter, made of brick and cement and covere d by a protecting build ing. This water is distributed by a Holly pumping engine having a capacity of from 5.000 000 to 6.000.000 gallons daily. This is required to be used only in case of accident to some flume or reservoir, or if repairs are required to the same, or if there should be severe storms which may cause the mountain supply to become roily. It can also be employed to supplement the gravity system in time of severe drought or an enormous conflagration. The pump house also contains another pump of 2,000,000 gallons daily capacity, both of which are kept in constantly perfect condition. Water rates are under municipal contiol, as is usual in the case of water companies and have always been satisfactory to the residents of the city.