Nutrient and suspended solid loads in the Laguna de Bay, Philippines

The Laguna de Bay is the largest lake in the Philippines and is situated 15 km southeast of the centre of Metropolitan Manila. The population of the capital region is growing out of proportion, especially in the watershed area of the lake. This development is endangering the resource Laguna de Bay due to the increasing discharge of nutrient and suspended solid loads from the drainage basin into the lake. During the EU-funded project “Laguna de Bay, Philippines: An Ecosystem Approach for Sustainable Management” a monitoring campaign on selected tributary rivers was conducted. Based on the results of this monitoring and an analysis of census data, the total annual loads were estimated at about 8000 t N, 2300 t P and 160,000 t TSS. The occurrence of the typhoon “Loleng” in the research area during the monitoring campaign made it possible to state that about 25% of the annual load is drained during such a weather situation.