MM is located in the hydraulically complex Pasig River – Laguna Lake – Manila Bay watershed,
which includes more than thirty tributaries within the urban area. Manila Bay is a pollution
hotspot in the East Asia Seas region (Map 1). Laguna Lake, located in the south of Metro
Manila, receives significant water pollution from MM region. Paradoxically, it is also a crucial
raw water source for the MM region. The Pasig River provides an important two-way hydraulic
connection between Manila Bay and Laguna Lake, and because of this interconnection, the Pasig
River serves as a conduit to transfer pollutants and salinity between Manila Bay, the Laguna
Lake, and other urban watercourses.