Although saltwater occasionally enters Laguna de Bay, experts claimed that the lake is still a freshwater lake. Its watershed covers 15 cities and 46 municipalities within Metro Manila and five nearby provinces.  Learn more about Laguna de Bay’s physical features, biological features, and geographical jurisdiction.

Laguna de Bay is the largest brackish water lake in the Philippines with a total surface area of 900 km². This is followed by Lake Lanao in Mindanao with a total surface area of 34, 700 hectares. Watershed is like a basin cut into halves. It starts from the highest ridge of the mountain where the rain falls and ends to the lake where the rain water drains.

The bathymetry figure above shows the graphical representation of the depth, and volume of water that the Laguna de Bay can contain. The lake's total volume appears to be diminishing at a rate of 3.3 X 106 M³/year. Silt-sized particles predominate in the surface sediments of Laguna de Ba'i.  However, clay-sized particles are abundant in the West Bay.

Depth

Unlike most of the Philippines lakes, Laguna de Bay is relatively shallow with an average depth of 2.5 m. But there is one spot where the lake is 20 m deep, the Diablo Pass. One can easily surmise why it was named that way.

Biodiversity in the Watershed

Laguna de Bay is home for various species of plants and animals. Did you know that about 48 percent of flowering plants and ferns endemic to the Philippines are found within the lake basin? Mt. Makiling, located between the provinces of Batangas and Laguna, has rich biodiversity with more than 2,000 species of flowering plants and ferns, 381 species of vertebrates including 45 species of reptiles, 22 species of amphibians, and 181 species of birds. Also, Mt. Banahaw, located in the province of Quezon, has high endemicity with 66-76 percent of the plants and animals endemic to the area.

Aquatic Biodiversity

The Laguna de Bay Region covers Metro Manila and other five neighboring provinces - Laguna, Rizal, Batangas, Cavite, and Quezon. All cities and municipalities located in Laguna and Rizal are part of the watershed.