Complex sentence: Construction began in 1955, and although all the elements of the entire scheme were not completed until 1965, water was first supplied in 1960 during the severe drought from 1960 to 1963.
Split into simpler sentences: Construction began in 1955, and although all the elements of the entire scheme were not completed until 1965. Water was first supplied in 1960 during the severe drought from 1960 to 1963.