According to the NYT,

The Chinese government plans to rechannel vast rivers of water from the Yangtze basin to the thirsty north, over three pathways of nearly 1,000 miles each at an official price tag of $58 billion. The eastern, coastal route is technically simple, though it will require 13 pumping stations, which will consume large amounts of electricity to lift water from near the mouth of the Yangtze to the higher north.
The main challenge is pollution. The route cuts across many of the world's most soiled river basins. Some scientists are quietly asking how the coastal route can ever affordably deliver water that will be safe enough even for industry, let alone drinking.

Perhaps toughest of all, in a country where no good patch of land lies idle, is how to provide for those like Mr. Zhang and his family who will be moved. One resident is quoted as saying "We never see a cent of the resettlement money. All these city, county, town and village officials stuff the money into their own pockets."