WELL, THAT WAS EASY:

The Rebirth of Prague's Vltava River: After decades of neglect and abuse, the picturesque river flowing through the Czech capital is being developed for residential and recreational use (Lucie Kavanova, 7/28/10, Business Week)

Jan Valek, laboratory director at the Prague office of Povodi Vltavy, a state river management company that has monitored the quality of the Vltava since the 1960s, said, "Under communism, the water was intensely polluted by heavy industry, which wasn't helped by the city's inefficient water treatment plants."

Meanwhile, the government was pouring money into tall, nondescript apartment complexes on the outskirts of the city and, along with subsequent governments, neglecting to invest in adequate flood protection. There was less and less reason to think of the Vltava as anything other than a channel for effluent or a barrier to be crossed on a bridge.

After 1989, that slowly began to change.

In the 1990s, the city made a major investment into a new water treatment system. That and the phase-out of heavy industry led to a dramatic improvement in water quality, although progress has slowed recently. "Lately, the improvement has not been that fast. I think we've hit our technological limit," Valek said. Still, he added, the Vltava is safe for swimming, and fishermen say new species are returning to the river.