The River Torrens, particularly its lower reaches, had become badly polluted following European settlement in 1836.Land clearance lead to increased runoff and erosion, with major flood events occurring in 1917 and 1933.An artificial channel, Breakout Creek, was completed in 1937, diverting floodwaters directly to the sea, and opening up areas of the western suburbs to housing development, particularly after World War II.Rapid expansion of housing in the eastern suburbs also took place at this time. Awareness of the risk of increased runoff leading to further flooding events lead to various proposals for flood mitigation in the 1950s and 1960s, including converting the river to a concrete-lined channel, or an underground storm-water pipe below a major highway.