is a lake located in the Chiba Prefecture of Japan, northeast of Tokyo.
Lake Tega is located entirely in the northwest of Chiba Prefecture, on the main island of Japan: Honshà «. As the crow flies, it is about north of Tokyo Bay, and north East of Tokyo Metropolitan Area.
Lake Tega has a total area of for a perimeter of . Its average depth is and its maximum depth of . It has the distinction of being composed of two bodies of water: Lake (main) Tega and Lake Shimotega, a watercourse of the watershed of the Tone River.