Even though the lake has a regulating effect, it is subject to water level variations that may exceed 3 m and reflect in the discharge at the outflow. At a short distance from the Petrohué locality, the river flows through the Petrohué Waterfalls.
Even though the lake has a regulating effect on the flow of water, its water levels can fluctuate significantly, exceeding 3 meters, which affects the amount of water discharged from the outlet. The river passes through the Petrohué Waterfalls near this location.