In 1902, the Aswan Low Dam was completed on the Nile River by the British. This threatened to submerge many ancient landmarks, including the temple complex of Philae. The height of the dam was raised twice, from 1907–1912 and from 1929–1934, and the island of Philae was nearly always flooded. In fact, the only times that the complex was not underwater was when the dam's sluices were open from July to October. It was proposed that the temples be relocated, piece by piece, to nearby islands, such as Bigeh or Elephantine. However, the temples' foundations and other architectural supporting structures were strengthened instead. Although the buildings were physically secure, the island's attractive vegetation and the colors of the temples' reliefs were washed away. Also, the bricks of the Philae temples soon became encrusted with silt and other debris carried by the Nile.

The temples had been practically intact since the ancient days, but with each inundation the situation worsened and in the 1960s the island was submerged up to a third of the buildings all year round. In 1960 UNESCO started a project to try to save the buildings on the island from the destructive effect of the ever-increasing waters of the Nile. First, building three dams and creating a separate lake with lower water levels was considered.[26] First of all, a large coffer dam was built, constructed of two rows of steel plates between which a 1 million cubic metres (35 million cubic feet) of sand was tipped. Any water that seeped through was pumped away.