Lava Lake was formed as a result of lava flows creating a dam along its east shoreline. Lava Lake is relatively old as evidenced by the extrusive vegetation occurring in the shallow areas. Rushes, waterlilies and other emergent plants are especially evident on the west and northern perimeter. Another indication of the lake’s aging is the 4 to 5 feet deep layer of muck located on the lake bottom as reported by divers.
Subsurface springs provide the primary inflow to Lava Lake. The springs are located in the northeast corner of the lake at a depth of 20 to 30 feet. Water temperatures from the inflow vary between 45° to 60° F. There are no permanent surface streams entering the lake, however, intermittent seeps do enter the lake from Wire Meadow. Lava Lake connects with Little Lava Lake only occasionally during periods of spring high water. The outlet channel is located in the southeast corner of the lake. Water level fluctuates an average of approximately 2.5 feet annually with maximum pool occurring in late summer. Timing of the peak pool level is consistent with flow levels typical of springs in the area.
For boat launch information see Lava Lake Boating Site, and Lava Lake Resort.