Seven Lakes of San Pablo

The Seven Lakes of San Pablo (Filipino: Pitong Lawa ng San Pablo) are seven crater lakes scattered around the City of San Pablo, in the province of Laguna, Philippines.

The seven lakes of the city are:

The lakes are maars or low-profile volcanic craters located in the San Pablo Volcanic Field. They are among the 200 small monogenetic volcanoes found along the Macolod Corridor, a rift zone between Mount Makiling and Mount Banahaw, which is part of the larger Southwestern Luzon Volcanic Field,. These craters are formed by phreatomagmatic eruptions, an eruption where ground water comes in contact with hot magma pushing up near the Earth's surface.

In a recent rocks and sediment analysis or petrographic study on the lakes and adjoining rivers in San Pablo, sulfate concentrations were considerably higher than the naturally occurring sulfates from volcanism. Samples were taken from other areas underlain with similar volcanic rocks from the old eruptions (e.g. Taal volcano) like Indang, in the province of Cavite and the La Mesa Watershed, the water supply reservoir for Metropolitan Manila. The analyses indicated that the elevated level of sulfates were not related to volcanism but anthropogenic or man-made, and among the causes are sewage, fertilizers, herbicides, pesticides etc.

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