Laguna de Bay is the largest lake of the Philippines covering a surface of 900 sq. km stretching over the provinces Rizal and Laguna. Larger cities located in the vincinity are Manila, Quezon and San Pablo. Laguna de Bay is fed by 21 rivers; its catchment area comprises about 3.820 sq. km. The only outflow of the lake which is, on average, 2.8 m deep, is the Pasig River.

The rivers flowing into Laguna de Bay serve as a refuse heaps for 60 % of the 8 million people living around the lake. Untreated sewage is another cause of pollution. Highly problematic is also intensive fishing and the large number of fish farms in this region. In 1993 already, the Laguna Lake Development Authority has presented a plan for a controlled economical and social development of the region with the main objective to maintain the quality of life for both - man and ecosystems.