Eventually, the caldera cooled. That allowed rain and snow to form a lake. Fumaroles and hot springs remained common and active during this period. Also after some time, the slopes of the lake's caldera rim more or less stabilized. Streams restored a radial drainage pattern on the mountain, and forests began to cover the landscape. It is estimated that it took about 720 years to fill the lake to its present depth of 594 m. Much of this happened during a period when the climate was drier than it is now. Some hydrothermal activity remains along the lake floor. That means that at some time in the future Mazama may erupt once again.