Without quoting directly from the text give me a summary of how turist visit the falls even if they are used for hydroelectric power production.

The Marmore Falls are used as a hydroelectric power plant, but to allow people to enjoy the spectacular water flow, the gates are periodically opened to present the full-sized river rushing into the void. 

The tourists can visit the falls on a fixed schedule (12:00 to 13:00, 16:00 to 17:00 plus additional times on holidays) following paths that allow them to reach the top of the falls.