Under a 1950 U.S.-Canada treaty the majority of the Niagara River is diverted to massive hydroelectric complexes. To hide the aesthetic impact of turning Niagara Falls into an energy waterscape, and retain tourism, the waterfall was physically reshaped and shrunk, and remedial works were built to control water flows and hydropower diversions. To achieve this, hydraulic engineers from the U.S. Army Corps of Engineers and Ontario Hydro relied on hydraulic models of Niagara Falls. Using an envirotech approach, I show how these physical hydraulic models were an integral part of the disguised design approach to remaking Niagara Falls, and I use this Niagara case study to critically explore the evolution of hydraulic modeling in early Cold War North America. The river and waterfall were transformed into a hybrid envirotechnical system, a submerged infrastructure that relied not only on steel and concrete, but also water, ice, and weeds.