Laguna de Bay, the largest lake in the Philippines, is just hundreds of meters away from the University of the Philippines Open University (UPOU) grounds. If you are standing on the side of the road going to the Makiling Forest via PCARRD road, you will be able to see the lake.
Laguna de Bay, or Laguna Lake, is situated east of Manila, between the provinces of Rizal to the north and Laguna to the south. Its total area is 911.7 km2, with a surface elevation of 2.0 m and is 41 km long. Looking from an aerial perspective, it is shaped like a stylized “W”. At the middle of the lake is Talim Island.
Its water drains to Manila Bay via the Pasig River. Laguna Lake has 21 tributaries, and among them the Dampalit and Pele Rivers in Los Banos, the Bay, Calo and Maitim Rivers in Bay, the Pagsanjan River (source of 35 percent of lake water) and the Santa Cruz River, which accounts for 15 percent of the water from the lake.
The lake has many uses. It serves as a temporary reservoir of water coming from Marikina River thru the Manggahan Floodway. Passenger boats traverse through the lake since the Spanish time. It also serves as source of water for the Kalayaan Pumped Storage Power Plant, an aquaculture area, and a source of fish, irrigation water, and food for the growing duck industry. It is also a tourist spot.
With its many uses, the lake is facing environment issues that are being addressed up to the present. Data shows that 60 percent of the estimated 8.4 million people staying around the Laguna de Bay dumped their solid and liquid wastes indirectly to the lake through its 21 tributaries. Of the total wastes going into the lake, 40 percent comes from agricultural wastes, 30 percent from domestic wastes and 30 percent from industrial wastes.
The Laguna Lake Development Authority (LLDA) reported results of 2005 sensitivity waste load model: 70 percent of biochemical oxygen demand (BOD) loadings come from households, 19 percent from industries and 11 percent from land run-off or erosion. Around 10 percent of the 4,100 metric tons of wastes generated by Metro Manila residents are dumped into the lake as well.