Fallen Leaf Lake is a mountain lake located near Lake Tahoe in El Dorado County, California. It was formed by glaciers that traveled northward during the last ice age, carving out the lake's oval shape. If the glacier had continued north it would be part of Lake Tahoe. The lake has one main tributary, Glen Alpine Creek, which provides more water in the spring from snowmelt. Various coniferous trees like incense cedar grow around the lake. Wildlife such as bobcats and the native Lahontan cutthroat trout also live in the area. However, the trout population has been negatively impacted by the introduction of non-native species.