 It was gradually formed by deposit of soil and sand from the San Diego River.The sandbar was used to dump materials from dredging of San Diego Bay for US Navy requirements in World War II which required a deepening of the harbor channel, further building it up.In the late 1940s The San Diego Harbor Commission undertook a dredging program that provided a new entrance to the yacht basin, and the dredged material was used to connect Shelter Island with Point Loma, and to further raise the island 14 feet above low tide; then another project raised it 7 feet above high tide.