La Mesa Watershed Reservation

La Mesa Watershed Reservation
Name	La Mesa Watershed Reservation
Location	Philippines, Metro Manila, Rizal
Area	2,659 hectares
Established	1938
Governing body	Metropolitan Waterworks and Sewerage System

La Mesa Watershed Reservation The La Mesa Watershed Reservation is a critical protected area supplying potable water to Metro Manila and surrounding provinces, managed as a municipal watershed and urban forest reserve. It functions as a drinking water source, flood buffer, and biodiversity refuge within the Greater Manila Area, and interfaces with numerous agencies, local governments, and civil society organizations.

Overview

The reservation was designated to protect the catchment for the Angat Dam, Ipo Dam, and the Metro Manila water system, and is administered by the Metropolitan Waterworks and Sewerage System (MWSS) with operational links to the Government of the Philippines, Department of Environment and Natural Resources, and local government units in Quezon City and Caloocan. The area intersects administrative boundaries near Rizal (province) and is proximate to infrastructure nodes like the Commonwealth Avenue, Nlex Harbor Link, and Lopez Avenue transport corridors. Stakeholders include the Philippine Atmospheric, Geophysical and Astronomical Services Administration, academic institutions such as the University of the Philippines Diliman and Ateneo de Manila University, and environmental NGOs like Haribon Foundation and WWF Philippines.

Geography and Hydrology

The watershed occupies upland terrain in northeastern Metro Manila and western Rizal, forming part of the larger Angat River catchment that feeds into the Ipo Dam and the Ipo–Angat water supply system. Topography includes low-gradient valleys, ridgelines, and the La Mesa Dam reservoir, which connects via conduits and aqueducts to treatment plants operated by Maynilad Water Services and Manila Water. Hydrological processes are influenced by the Pacific typhoon belt, seasonal monsoon patterns monitored by PAGASA, and land use changes in adjacent barangays. Hydrometry, sedimentation, and watershed yield assessments have been subjects of study by the Philippine Institute of Volcanology and Seismology and university hydrology departments.

History and Development

The area was declared a watershed reserve during the Commonwealth period and expanded under postwar reconstruction initiatives tied to urbanization in Manila and suburban growth in Quezon City. Major historical events affecting the watershed include infrastructure projects from the American colonial period, postwar population influxes associated with the Hukbalahap Rebellion aftermath, and policy shifts under administrations such as those of Presidents Manuel L. Quezon, Ramon Magsaysay, and Ferdinand Marcos. Legal instruments like proclamations and executive orders from the Office of the President of the Philippines have defined boundaries and regulations; litigation and advocacy involving courts such as the Supreme Court of the Philippines have influenced tenure and land use. Partnerships with international donors and agencies including the Asian Development Bank, World Bank, and bilateral programs from Japan International Cooperation Agency have supported watershed management projects.

Ecology and Biodiversity

The reservation contains remnant lowland and montane forest patches supporting species recorded by the Department of Environment and Natural Resources and conservation groups. Flora includes native dipterocarps, endemic understory plants, and riparian vegetation cataloged by university herbarium programs. Fauna inventories report populations of resident and migratory birds monitored by the BirdLife International partner organizations, small mammals studied by the National Museum of the Philippines, and amphibians and reptiles surveyed by academic herpetologists from Ateneo de Manila University. The area serves as an urban biodiversity island similar to other metropolitan green spaces like La Mesa Eco Park and provides habitat connectivity to nearby green corridors such as the Marikina Valley and the Manila Bay-to-riverine systems.

Management and Conservation Efforts

Management is coordinated among the Metropolitan Waterworks and Sewerage System, the Department of Environment and Natural Resources, the Quezon City Local Government, and civil society coalitions including the Kalikasan People’s Network for the Environment and local community associations. Conservation measures have included reforestation, sediment control works funded by multilateral development banks, enforcement operations with the Philippine National Police and local barangay officials, and community-based livelihood programs supported by NGOs and the United Nations Development Programme. Monitoring uses remote sensing and GIS tools developed with universities and agencies like the Philippine Space Agency and the National Mapping and Resource Information Authority.

Recreation and Public Use

Designated recreation areas such as parts of the La Mesa Eco Park provide public access for environmental education, hiking, birdwatching, and organized events coordinated with tourism offices like the Department of Tourism and civic groups. Visitor management balances public recreation with source-water protection through permit systems administered by MWSS, partnerships with educational institutions (e.g., field courses from the University of the Philippines), and programming by NGOs such as Haribon Foundation and urban forestry initiatives linked to the Arbor Day Foundation-type campaigns.

Threats and Challenges

The watershed faces pressures from illegal logging, informal settlements in adjacent barangays, land conversion tied to urban sprawl in Quezon City and nearby municipalities, pollution from runoff and domestic waste, and climate change-driven variability tied to stronger typhoons tracked by PAGASA. Institutional challenges include inter-agency coordination across entities like the Department of Interior and Local Government and MWSS, enforcement limitations within the Philippine legal system, and funding constraints that affect long-term restoration. Conservation responses involve litigation by environmental advocates, policy instruments enacted by the Office of the President of the Philippines, and international climate adaptation financing from multilateral partners.

Category:Protected areas of the Philippines Category:Watersheds of the Philippines