CHAPTER IX. THE CROTON WATERSHED. THE Croton River (see Plate 54) lies entirely in the State of New York. It is formed by three branches (known respectively as the East, the Middle, and the West Branch), which rise in the southern part of Dutchess County, flow in a southerly direction through Putnam County, and unite near its south boundary. across Westchester County to the Hudson about 30 miles from the city of New York. Titicus, Cross, Kisco, and Muscoot rivers. The river continues in a southwesterly course River, into which it empties at Croton Point, The principal tributaries of the Croton are the The watershed of the Croton, extending about 33 miles north and south and 11 miles east and west, lies almost entirely in the State of New York, only a small portion being in Connecticut. Its area amounts to about 339 square miles above the Old Croton Dam, and to 360 square miles above the New Croton Dam, now being constructed. is very hilly. Its surface soil is composed principally of sand and gravel. and peat are found in a few localities, but only to a very limited extent. tion consists generally of gneiss. Strata of limestone, some micaceous and talcose slates, veins of granite, serpentine, and iron ore occur in a few places. The watershed Clay, hardpan, The rock forma The monthly and annual amount of rainfall in the Croton watershed from 1870-1895 are given in the table on page 309. The average annual amount for this period was 48.38 inches, the minimum and maximum being respectively 38.52 and 63.51 inches. During the driest year of the above period an amount of water equivalent to 15 inches over the whole watershed (700,000 U. S. gallons per square mile) flowed off in the Croton River. If this amount of rainfall were collected for the whole drainage area above the New Croton Dam (360.44 square miles) and stored without any loss, it would furnish an average supply of 250,000,000 gallons per day. Thirty-one lakes and ponds, fed by streams or springs, are contained in the Croton watershed. Many of them have been utilized as natural storage-basins by cutting down their outlets and building dams across the same. A cast iron outlet-pipe, controlled by a stop-cock, passes through each of these dams. The amount of available storage in the artificial and natural basins in the Croton watershed, prior to the commencement of the new works, is given in the report of Isaac Newton, Chief Engineer Croton Aqueduct, dated January 30, 1882, as follows: H ARTIFICIAL AND NATURAL STORAGE IN THE CROTON BASIN, JANUARY 1, 1882. U. S. Gallons. 2,727,000,000 4,004,000,000 575,000,000 565,000,000 165,000,000 380,000,000 200,000,000 50,000,000 170,000,000 105,000,000 100,000,000 75,000,000 60,000,000 230,000,000 110,000,000 25,000,000 Boyd's Corners reservoir..... Lake Mahopac Lake Gleneida *. Lake Gilead * Lake Waccabuc.. Lake Tonetta.... Barrett's Pond*.... China Pond. White Pond..... Pine Pond..... Long Pond.. Peach Pond.... Cross Pond.... Haine's Pond........... .. as yet. * Total gallons.... 9,541,000,000 NOTE.—The lakes and ponds marked * are now (1895) owned by the city. Water is drawn from the others by special agreement. The total amount of storage water obtained from the above sources during the dry years 1880 and 1881 was as follows: Total storage drawn in 1880.... Total storage drawn in 1881.... Name. East Branch reservoir Since Mr. Newton wrote his report the storage in the Croton basin has been largely increased by the construction of the East Branch and Titicus reservoirs. Other storage basins are being constructed by the Aqueduct Commission and the Department of Public Works. The new reservoirs which have been completed since January 1, 1882, or are in course of construction are given in the following table: NEW RESERVOIRS IN THE CROTON BASIN. 8,520,000,000 U. S. gallons 8,605,000,000 44 66 44 64 66 Dept. Pub. Works Capacity. US Gaons. 9.028,000,000 7,000,000,000 9.000.000.000 32.000.000.000 7.000.000,000 Total new storage.. NOTE.-The capacities of the reservoirs, with the exception of the first, are only approximately known 64,028,000,000 The location of all the new and old reservoirs, lakes, and ponds in the Croton basin are shown on Plate 54. When the new reservoirs have all been completed the total amount of available storage in the Croton basin will amount to 72,633,000,000 U. S. gallons. Mr. A. Fteley, Chief Engineer of the Aqueduct Commission, states, in his report on the construction of the new works from 1887-1895, that a storage of 70,000,000,000 gallons will insure a daily supply of 280,000,000 gallons. When the old Croton water-works were constructed (1837-1842) the watershed of the Croton River was but sparsely inhabited. Tests of the water made when it was first introduced and others of later date are given on page 285. The deterioration of the quality of the water, shown by these tests, is due to the increase of population in the watershed. In 1888 the population on the watershed draining into Croton Lake was estimated at about 20,000, distributed in 1879 houses in the town of Brewster, in small villages and on farms. The number of domestic animals (cows, horses, pigs, and sheep) on this part of the watershed was estimated at 12,243. As the Croton water was being much polluted by manufacturing wastes, the drainage from manure-heaps, pigsties, etc., the Board of Health of the State of New York had a careful sanitary survey made of the watershed of the Croton in 1888, and framed the rules and regulations given on page 277 for protecting the purity of the water-supply of New York. For some years these regulations were not enforced. In March 1893 the Legislature passed “An Act to provide for the sanitary protection of the sources of the water-supply of the City of New York" (chapter 189 of the Laws of 1893, known as the Webster Act), which enables the Department of Public Works of New York to condemn all property adjacent to any stream, pond, or reservoir, used for the city's water-supply. With the power given by this Act energetic measures were taken at once by the Department of Public Works and by the Aqueduct Commissioners to remove all sources of pollution from the Croton watershed. To protect the water-supply in the future the city is acquiring gradually a margin of about 300 feet around all reservoirs and along all streams emptying into the same. CHAPTER X. RESERVOIRS CONSTRUCTED BY THE AQUEDUCT COMMISSION. THE original plans of the Department of Public Works for an increased supply of water from the Croton watershed involved the construction of a large storage reservoir, which was to be formed by building a high masonry dam across the Croton River near the Quaker Bridge (see page 109). The storage thus obtained was to be increased subsequently, if required, by the construction of smaller reservoirs on the branches and affluents of the Croton. Owing to the opposition to the building of the Quaker Bridge Dam which was made by some citizens at the public hearings, the construction of the proposed reservoir was not begun simultaneously with the building of the new aqueduct, as originally intended. The result was that some delay occurred before any additional storage was obtained. While the question of constructing the Quaker Bridge Dam remained undecided, the pressing necessity of obtaining additional storage caused the Aqueduct Commissioners and the Department of Public Works to commence the construction of the four smaller reservoirs known as the East Branch, Titicus, Carmel, and Amawalk reservoirs. The plans for these reservoirs, with the exception of the one at Amawalk which is being constructed by the Department of Public Works, were all prepared by the engineer of the Aqueduct Commission. The designs were based upon the same general principles. Where the water to be impounded was to have considerable depth, the central part of the dam was constructed of masonry, provided a rock foundation could be obtained at a reasonable expense. The overflow-weirs were in all cases built of masonry and were made sufficiently wide to pass safely in 24 hours a quantity of water equivalent to not less than 6 inches of water over the whole drainage-area of the respective reservoirs. The bulk of the masonry consists of rubble made of stone quarried in the vicinity of the dams. In some cases the facing-stone was brought from a distance. As no clay or material suitable for puddle-walls could be found near the reservoir, earthen dams, when used, were always provided with a core-wall of rubble masonry, founded on rock, hardpan, or compact earth. The East Branch Reservoir (known as the Double Reservoir I; see Plate 54), constructed near the town of Brewster, Putnam County, N. Y., consists of the following two basins: The two reservoirs have about equal storage capacity, but their watersheds differ very much in area. In order to equalize the supply received by each, the two basins were connected by a tunnel 10 feet in diameter and 1778 feet long. The tunnel was excavated entirely in rock and was lined with brickwork, backed by rubble masonry. (see Plate 111). The Sodom reservoir (see Plate 112) was formed by constructing: Ist. A masonry dam, 500 feet long, across the east branch of the Croton River. 2d. An earthen dam with rubble core-wall, 600 feet long, on a ridge parallel with the river and about 75 feet above it. 3d. A masonry overflow-weir, 500 feet long and about 8 feet high. The earthen dam starts from the east abutment of the masonry dam and is in front of this structure and nearly perpendicular thereto. The overflow-weir forms a continuation of the earthen dam. The masonry dam was constructed according to the profile shown in Plate 114. Its principal dimensions are: Before the construction of the dam was commenced, the river was diverted from its old. bed in the following manner: A crib dam was built across the stream, about 80 feet above the site of the dam. The water, thus turned from its ordinary course, was conducted by a canal, excavated into the west hill, to a point about 500 feet below the dam. The east branch of the Croton River is generally an insignificant stream, but during freshets its flow amounts, at times, to 250,000 cubic feet per minute. To give sufficient protection to the work the diversion canal was made 26 feet wide and 15 feet deep, dimensions which subsequent experience fully justified. The river being turned from its course, the easterly half of the dam and the gate-house near the centre of the structure were first built to a height of 25-30 feet above the dischargepipes. During the dry season of 1889 the water was turned into these pipes, and the remaining part of the dam was then constructed. The dam was founded entirely on rock, with the exception of a small portion on the west side, which was above the water-line. The rock bottom was found to be partially disintegrated and fissured. All unsound portions were removed by barring or by light blasts. Before the masonry was laid, the foundation was swept with wire stable-brooms and washed clean with streams from hose-pipes. The pockets in the rock were then filled with concrete or rubble (the latter being generally used) and the foundation "levelled up." A large quantity of water found its way through the loose rock above the foundation. and, in some cases, through seams in the rock bottom. When the water came from the bottom, the small streams, in which it issued, were led to small wells, about two feet in |