Good afternoon John,
I think the reasons for Steve Bracks' resignation are fairly obvious. The Victorian government's opposition and apparent high court challenge over the federal government's plan to take control of the Murray Darling river system is ridiculous, there is a precedent which will allow the federal government to forcefully take control of the river system, and the high court challenge will only delay the inevitable, waste a whole heap of taxpayers money, and make Bracks look like a goose when Victoria loses the challenge.
Steve Bracks, after the opposition he has put up to the plan, can't really back down and give the river to the federal government, but he knows the fallout from losing the court case will be disastrous for him. Much like Bob Carr did to Morris Iemma, Steve Bracks is getting out while he's on top, and leaving the mess to his successor.
Enjoy your weekend,