The School Street Hydroelectric Project is located on the Mohawk River at Cohoes Falls. This area around Troy and Cohoes, NY, where the Mohawk drains into the Hudson River, was one of the most important industrial centers in 19th century America. Such industrial development drew largely on the ingenuity of American inventors who developed new processes for making iron and shirt collars and textiles and more. However, it also drew upon the ability to generate vast amounts of power. In the mid-19th century, the Cohoes Company used the falls of the Mohawk to create a remarkable multi-level canal system that powered a vast array of factories in Cohoes. Most of this canal system is no longer visible. The biggest remaining artifact is the upper gatehouse that controlled the flow of water into the power canal above Cohoes Falls. The original machinery to open and close the gates, from 1866, remained in the upper gatehouse until 2009. I had the chance to carry out the HAER photographs of these remarkable machines before their removal.
Upper Gatehouse interior
When I was working as the Senior Cultural Resources Specialist with Kleinschmidt Associates, I did quite a lot of work at the School Street Hydroelectric Project in Cohoes. Kleinschmidt was coordinating the application for the new FERC license, and I handled all of the cultural resources issues. This was a very large undertaking, given all of the layers of history within the Project boundary–Cohoes Falls was vital to the history of the Haudenosaunee (Iroquois) Nation, and provided an enormous challenge to the builders of the Erie Canal in 1817, which bypassed the falls on the south bank of the Mohawk River; using this tradition of canals, the Cohoes Company created a vast industrial complex on the downstream side of Cohoes Falls, using an innovative series of multi-level canals that provided multiple sources of power; the modern hydroelectric powerhouse then was built in 1922, using many components of the original Cohoes Company’s canals.
Perhaps the most vital element in the Section 106 process at School Street was the fact that the remaining components of the Cohoes Company within the hydroelectric project contribute to the Harmony Mills National Historic Landmark district. These included the dam across the Mohawk River, the upper gatehouse that was at the southern end of the dam and controlled the flow of water into the power canal, and the power canal itself. The upper gatehouse, together with the dam, was built in 1866, and was constructed of brick. The dam forced the water of the Mohawk River into a forebay immediately above the upper gatehouse. The water then passed into the power canal through a series of eight gate openings, each of which was controlled by a slide gate made of timber. The timber gate could be raised or lowered vertically using a gate operator that featured two cone-shaped gears that, when brought together, worked by friction rather than by toothed gears. An 1885 study by the U.S. Census of the Water Power of the United States provided a thorough description of these gate operators:
The machinery for raising and lowering the gates is very easily operated and satisfactory in working. The turbine . . .is at the river end of the bulkhead, and operates three lines of shafting; one of these, 2 ¼ inches in diameter, runs in at right angles to the stream and connects with the head-gates; the other two run in either direction parallel to the stream and connect with the waste-gates. Each gate has attached to it two vertical iron posts with racks. Opposite one post of each gate is a pair of beveled friction-wheels revolving in parallel vertical planes; a third wheel, revolving in a plane at right angles to these, can by a small hand-wheel be brought in contact with either accordingly as it is desired to raise or to lower the gates.
This was an innovative system developed by William Worthen, a Civil Engineer who created a similar system of gate operators for the Shelton Dam across the Housatonic River in Connecticut. A plaque in the upper gatehouse testifies to Worthen’s role as the engineer for the redevelopment of the Cohoes Company’s dam and gatehouse in 1866.
The Cohoes Power and Light Company first built a hydroelectric powerhouse on the Mohawk River downstream of Cohoes Falls in 1911, using the Cohoes Company’s power canal system. Cohoes Power and Light then built the current powerhouse, located immediately below the base of the falls, in 1922. The new powerhouse used vastly larger amounts of water to generate electricity, and the new company enlarged the power canal to provide this increased water supply. In order to do so, they also needed a larger upper gatehouse. Instead of building a enlarged gatehouse, they simply added a section onto the existing upper gatehouse; the contrast between the two buildings is startlingly obvious.
The new, 1922 section of the upper gatehouse featured three gate openings, each controlled by a tainter gate. Each gate in the new section was controlled by a larger lift structure that was powered by hydraulics. The original 1922 hydraulic tank and pump remained in the upper gatehouse.
The School Street Hydroelectric Project is owned and operated by what is now Brookfield Renewable Energy. FERC issued a new license to Brookfield in 2007 to operate the School Street Project. Kleinschmidt had worked with Brookfield to prepare the license application, and continued to work with Brookfield to implement the terms of the license. These terms included replacing the original 1866 and 1922 gate operating machinery with modern equipment. Since the gate operating machinery contributed to the significance of the National Historic Landmark district, it had to be documented according to the standards of HAER, with the products going to the National Park Service for approval, and eventual curation at the Library of Congress. The exterior of the upper gatehouse had been documented for HAER in 1970, with an addendum in 1985 for a portion of the upper gatehouse that was removed. I was honored to carry out the documentation of the machinery in 2007, as a second addendum. The NPS finally approved the documentation package in October 2009. Here is a copy of the historic narrative that was approved by the NPS:
In the summer of 2009, after I had left Kleinschmidt and was working for myself, I had the opportunity to visit School Street when the power canal was dewatered. It was an odd thing, to walk along the bed of the power canal which normally was under some 20 feet of water, but it provided a fascinating view of the canal and of the downstream face of the upper gatehouse. I have included some photographs from that trek in the gallery above.
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