Board of Water Supply. Old Croton Aqueduct; High Bridge. View looking southwest. The flow of the Old Croton Aqueduct is carried across the Harlem River on an imposing structure known as High Bridge which is located about opposite 174th Street, Manhattan. Pipes are placed in the upper part of the structure to carry the flow of the aqueduct. The cost of this bridge was about 1,000,000 dollars. A few hundred feet to the north of this bridge, the waters of the New Croton Aqueduct flow through a tunnel constructed about 300 feet below the surface of the river. The tunnel construction is the modern economical type. At the west end of the bridge is seen the High Bridge Tower with the High Bridge Reservoir at its base. The reservoir was put into service in 1870 and the tank in the tower in 1872. the reservoir, the water surface of which is 218 feet above level, is used as an equalizing basin for the intermediate distribution service, the water for which is obtained from the Croton low service pumped at 179th Street and 98th Street stations. The tower is used as an equalizing pipe for the high service, the water being pumped at 179th Street station, the tower overflow being at an elevation of 336 feet. May 12, 1916.