There are giant artificial lakes on both sides of the Niagara Gorge, just downstream for Niagara Falls. Both are essentially giant batteries, ready to generate electricity when needed.
One belongs to the New York Power Authority. The other belongs to Ontario Power Generation.
The Ontario plant is just coming back into service after a massive rehabilitation of the 750-acre lake near the Lewiston-Queenston Bridge.
"We had to take all the water out of the reservoir. About 20 billion liters of water came out," said Ontario Power spokesperson Neal Kelly.
"We installed some new liners and then, of course, there was targeted grout injections just to strengthen the reservoir's integrity and we did that to ensure the highest level of safety for our employees and the surrounding community."
The project cost $60 million (Canadian). The reservoir, which was under repair for 10 months, serves as the water supply for the Sir Adam Beck power plant.
"Ours was built in 1957. The one in Lewiston, NY that New York Power Authority has was built some time in the 1960s and it is slightly larger," Kelly explained.
"It is the same thing. They, like us, pump up water in night time when demand is low and then release it to run through the generators during the day when demand is high."
Both plants are important in the power grid for the American Northeast and the Province of Ontario and its neighbors because electricity moves back and forth across the border constantly.