Complex sentence: The last time the dam had been improved upon was in 1988 and after a recent investigation, there was now a need to conduct preventative maintenance and upgrade of the flood retention protection to safeguard the dam and the residential properties below.
Split into simpler sentences: The last time the dam had been improved upon was in 1988. After a recent investigation, there was now a need to conduct preventative maintenance and upgrade of the flood retention protection to safeguard the dam and the residential properties below.