In the Metropolitan Water District of Bos ton are several other corporations and the sup ply is metrcd for different uses.
New York City obtains its water supply from six different sources. Those are with their respective available daily yields: (1) The Croton watersheds with 336,000,000 gallons; (2) The Bronx and Bryan watershed with 18,000,000 gallons; (.” the Esopus watershed with 250,000,000 gallons to be augmented by the Schoharic Creek addition of 250,000,000 gal lons; (4) the Long Island watersheds com prising the Ridgewood and other systems, and Including Queens on reserve) with 150,000,000 gallons; (5) the Staten Island watershed, in reserve, with 12,000,000 gallons, and (6) private water companies with 34,000,000 gallons. The foregoing amounts, except that from Schoharie Creek, soon to be added, are given in the in structii e paper of Dr. Frank E. Hale, chief chemist of the Department of Water Supply, (as and Electricity. No other modern system has ins o!vect a greater expenditure, except pos si' ly that of London, and none is delivering a greater quantity lin!, ss it be that of Chicago. Ccrainlv its tr,:ility is as pure and wholesome as that of any city in the world. All its catch ment area are under the supervision of sani tary inspectors and its Catskill supply is largely from land, owned and cleared by the city. Escry precaution has been taken to avoid pol lution of the sources, and some of which are in the and slopes of mountains. Physical, chemical, bacterial and microscopical examinations are periodically made of the sources.
Several modem processes of purification in cluding liquid chlorine at several plants are in use They comprise an aerator at the Asbolcan servo. r, a coagulation plant above the kensico reservoir on the Catskill aqueduct, a Dun woodie chlorination plant on the new Croton aqueduct a chlorination plant on the Catskill supply below Kensico reservoir, following aeration, a slow sand filter plant below Oak land Lake in Queens County, whose bacterial ef ficiency is supplemented by liquid chlorine and several slow and several rapid sand filter plants located on various conduits of the minor soarers of supply. One of the latter is at Ratsley Pond. Micro-organisms which are destroyed by treatment with copper sulphate, and iron. have been found in some of the
waters The processes used have been efficient in purifying any waters that have been so in fested.
and other supplies, including about 90.000,000 gallons of ground waters from Long Island.
In 1918 there were daily distributed for all purposes in all the boroughs of Greater Ncw York approximately 000,000,000 gallons, that be ing a little more than the rate of 100 gallons per capita.
The waters of the Schoharie Creek or water shed are to be impound( d in a reservoir at Gil boa dam, and carried in a tunnel 18 miles long under the Shandaken Mountains into the upper reaches of the Esopus Creek and thence into the Ashokan reservoir to double the present (1919) supply. When that improvement is completed there will be 500 million gallons available a day for New York city, from the Catskill and Scho Bacteria in the waters of the several Croton and Catskill aqueducts varied from 17 to 68 per cubic centimeter, but chlorination reduced the number from 46 to 91 per cent. In 1918 storage in the Asbokan reservoir reduced B. roll 99.8 per cent and other bacteria 69 per cent. Several species of Diatom:wee. Cyarsopkycrer, Protozoa and Cresotiris have been localized in the waters of the Ncw York supply.
The Esopus supply is from several streams, whose waters are conducted into the Ashokan reservoir 91 miles northwest of the city and thence are conducted in an aqueduct having a daily capacity of 500,000,000 gallons down the west side and under the Hudson 1,100 feet below its surface (Fig. 2) and up to the Kensico reservoir, thence to the Hill View reservoir with an elevation of 295 feet, which determines the •bead• of the Catskill supply and thence in a tunnel extending down through New York City to the distributing reservoirs in the sev eral boroughs. These receive also the Croton harie watersheds, having an area of 571 square miles. The Ashokan reservoir has an eke'. tion of 587 feet above tide-water and its outlet is 495.5 feet above tide-water. Its capacity is 128 billion gallons. The Gilboa reservoir will have a capacity of 20 billion gallons, and has an elevation of upwards of 1,100 feet above tide water and is 125 miles from New York City.