As a kid on the Nepean i remember when we had floods almost annually. I recall them being Spring/Autumn events, and they would block the lower entrance to Camden as the bridge there went under, meaning traffic chaos on the Macarthur bridge, and the dream of school being shut until it subsided.
Re Burragorang, is it actually at 90%? I make it a bit lower than that, with Nepean/Avon being chockers, giving us a cumulative for the Sydney catchments of around 87%:http://www.iliveinsydney.com/water/damstats.php
Still, more than capable of filling up if the predictions for the next week come true.
Also, BOM has issued a severe warning a few mins ago:http://www.bom.gov.au/nsw/warnings/severe.shtml