For the first time since 2019, the water in Lake Tahoe is fully mixed. When a body of water is “mixed,” cold water at the surface sinks all the way to the lake bottom. Water that was previously at the bottom rises to the top. This mixing phenomenon happens about every four or five years in Lake Tahoe. … This comes as a result of a much colder-than-average winter for the Tahoe Basin. Scientists with the UC Davis Tahoe Environmental Research Center track Lake Tahoe’s water temperature each day. They say that right now, the temperature throughout the entire lake is pretty much the same, a sign that the water has indeed mixed from top to bottom.