India, May 10 -- The river has a name older than memory. Before the Bhagirathi shifted its course, before the Hooghly was widened by silt and monsoon into the channel that defines Kolkata today, there was the Adi Ganga-the Primal Ganga-an ancient distributary flowing southward through what is now the heart of South Kolkata. It is said to have been the original sacred waterway, the river by which the Ganges first reached the sea. Pilgrims bathed in it, merchants sailed it, and the first Bengali settlements that would grow into a commercial colossus were planted on its banks. Today the Adi Ganga is a shadow of itself-choked with effluent, reduced to a trickle in many stretches, its ghats crumbling, its sacredness dishonoured. But its fate i...