 The construction was first proposed in 1989 but did not begin until 2002.The roller-compacted concrete backup dam was required by the federal government as a mechanism for preventing flooding if an earthquake of similar magnitude to the 1886 Charleston earthquake was to occur again in South Carolina.It was projected that large parts of the Columbia, SC metropolitan region (encompassing around 135,000 people) would have been in the flood region if the original dam was damaged.