Can the Hawkesbury River Ever be Fully Tamed?

For most Sydneysiders, the Hawkesbury River with its principal tributary the Nepean was thought of as a placid scenic recreational waterway, flanking Sydney on its distant west at the foothills of the Blue Mountains and looping around Sydney’s northern shoulders at Broken Bay before flowing into the Tasman. This image of peaceful tranquility was shattered in March as a result of exceptionally heavy rainfalls over four days in the Greater Sydney region—400 to 600 millimetres (sixteen to twenty-four inches) almost half the usual yearly rainfall. This rain triggered an overflow on the spillway of the Warragamba Dam, leading to flooding down the length of the Hawkesbury flood plains. The flood levels reportedly reached 12.5 metres at the historic township of Windsor, deep enough to drown the recently constructed road bridge but below the 14.2-metre level of November 1961, a year after the completion of the Warragamba Dam.

The March inundation led to speculation that the floods…