The Mojave River drained into Lake Manix, with the formation of the lake reflecting increased precipitation in the San Bernardino Mountains. Local arroyos also drained into the lake. It has been estimated that runoff had to increase by a factor of about ten to form Lake Manix. Lake Manix contained over of water, possibly as much as . Water levels in the lake frequently fluctuated by . It formerly was the Mojave River's terminal lake, and received about of sediment. The Coyote Basin was not permanently coupled to the main lake body; its relatively large surface area and consequently high evaporation would have stabilized lake levels when it was connected to Lake Manix proper.