amount of garbage goes uncollected and is often disposed of in the region’s rivers and lakes (FUSP, 2002b).

The situation for industrial solid waste is worse. Environmental problems have accumulated over the last few decades in water source protection areas, a result of industrial occupation that is either irregular or which occurred before the water source protection legislation came into effect or before the adoption of legal parameters to control soil and water pollution by industrial effluents.

In a recent study of Greater São Paulo’s 39 municipalities, only 9 declared that they regulate the disposal of industrial waste, while 26 declared that they do not and 4 municipalities did not respond (FUSP, 2001).

**Water quality** . According to the water quality information produced by the state environment agency (CETESB), the principal rivers, including the Tietê, present reasonable water quality conditions in the upstream portion of the basin, with adequate levels of dissolved oxygen. However, in the downstream portion, from the border of São Paulo municipality onwards, these rivers are classified as of extremely low quality (FUSP, 2002a and 2002b).

The quality of the Guarapiranga reservoir continues to worsen, even with the launching of the pollution control program (Guarapiranga Project) in 1992, conducted in partnership with the World Bank. The Billings Reservoir has shown “good” to “excellent” ratings in terms of organic pollution since 1992, when the transfer of the heavily polluted water from the Pinheiros River by the electricity company was restricted. However, there are still concerns about eutrophization and about the presence of some heavy metals, such as lead. In the Alto-Tietê System, the reservoirs have good water quality conditions, but in the upstream part of the basin some have begun to show an increase in phosphorus and heavy metal ratings.

**Urban Flooding.** Land use in the São Paulo metropolitan region has followed a pattern of densification and verticalization resulting in increased impermeability of soils. The result has been that urban areas are both the causes of increased flooding and its main victims. The Alto-Tietê Water Resources Plan located 72 critical points during the floods of 1998-1999. Other critical sites are spread through the region, along the Tietê River itself as well as along its tributaries. Urbanization has led to the impermeability of 37% of land within the basin, further aggravating the situation. Like water source protection, this is a problem whose control depends on land-use planning. This is, however, a municipal responsibility, outside the control of water resources policy (a state attribution). Since 1998, a Macro-Drainage Plan for the Alto-Tietê basin —seeking to diagnose existing and expected problems and to devise solutions from a technical, economic, and environmental perspective— has been under preparation.

**Growing urban demand and inter-basin transfers.** So-called “relative water scarcity” (when water is abundant in quantity but inadequate in quality) led the Alto-Tietê basin to import water from neighboring basins in the 1970s. The water diverted from the Piracicaba and Capivari basins to the Guarapiranga System is currently responsible for half of the total water supplied in Greater São Paulo. However, a major conflict has emerged over recent years because the Piracicaba basin has undergone rapid population and economic growth, increasing significantly its own demand for water as well as the

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