Revival of a Sao Paulo River.

• Author: Holston, Mark
• Position: Upfront

ONE OF THE FIRST sights visitors to Sao Paulo, Brazil, encounter is not a pretty one. At initial glance, the stagnant waters of the Tiete River have all the earmarks of an open sewer. What was once a naturally meandering watercourse has today been confined to a channel imprisoned by two of the city's major thoroughfares. The river's banks are virtually devoid of any natural vegetation, and its fetid waters are clogged with human waste; poisoned with runoff from industrial sites; choked with pesticides, sediment, and chemicals; and littered with refuse. According to scientists, the badly degraded river is all but ecologically dead. It is not only an eyesore, but also the source of public-health concerns. Outbreaks of hepatitis have been common among communities that border the waterway.

Since the founding of Sao Paulo in 1554, the Tiete and the city's other river, the Pinheiros, have been the primary source of water for the city's residents. Today, the vast majority of the metropolis's estimated twenty million inhabitants depend on water supplied by these two sources for their daily needs, while water taken from wells that tap the region's shallow aquifers supply the rest. Efforts to provide safe drinking water to the city's residents have become an increasingly daunting task, exacerbated by Sao Paulo's rapid population growth.

Guaru, the city's primary water treatment plant and South America's largest such facility, processes nearly eight thousand gallons of water a second, adding chlorine and fluoride to the over 700 million gallons of water it treats daily. However, a city of Sao Paulo's size should have the capacity to provide almost twice that amount. Wastewater produced by over three-quarters of the city's residents flows directly into the Tiete, adding to pollution woes. At the same time, the region's heavily tapped groundwater resources are being significantly depleted--the water table is sinking over thirteen feet per year.

Serious efforts have been under way since the early 1990s to clean up the Tiete. Today, they are picking up pace. Over $1.1 billion, including loans from the Inter-American Development Bank and locally generated matching funds, has been put into action. Engineering projects to control the introduction of human waste into the river and educational efforts to...