Complex sentence: When all the mills closed in the wake of the Great Depression, city leaders ignored the potential of the falls for tourism and leased the flow rights to a series of power companies including Niagara Mohawk and Orion Power.
Split into simpler sentences: When all the mills closed in the wake of the Great Depression, city leaders neglected the potential of the falls for tourism. They leased the flow rights to a series of power companies, including Niagara Mohawk and Orion Power.