Sec. 4. As used in this chapter, "shoreline or water line" means:
(1) if the water level has been legally established, the line formed on the bank or shore by the water surface at the legally established average normal level; or
(2) if the water level has not been legally established, the line formed by the water surface at the average level as determined by:
(A) existing water level records; or
(B) if water level records are not available, the action of the water that has marked upon the soil of the bed of the lake a character distinct from that of the bank with respect to vegetation as well as the nature of the soil.