In the past, 23 endemic fish species inhabited the Laguna Lake, including the monetary-valued white goby (Glossogobius giurus), grunt (Therapon plumbeus) and catfish (Arius manilensis).
Today, only six varieties of fish thrive in its waters.
Also at one time, the lake had 13 kinds of aquatic plants growing above the water. Now only the lowly kangkong and the resilient water lily have survived the heavily polluted waters of the dying lake.
In the late 1970s, the lake’s depth was measured seven meters. Today, it has gone down to 2.5 meters.
“From all indications, Laguna Lake is destined to become another classic case of the ‘tragedy of the Commons,’” wrote Celso Roque in a foreword for Laguna de Bay: Problems and Options.
Rodolfo Tingzon, when he was still a Laguna representative, shared the same view. “Laguna de Bay represents the most tragic example of environmental degradation in this country,” he deplored.
There is no updated inventory of lakes in the country at present. However, during the recent Second National Congress on Philippine Lakes convened by the Philippine Council for Aquatic and Marine Research and Development (PCAMRD) and the Southeast Asian Regional Center for Graduate Study and Research in Agriculture (SEARCA), some 216 lakes have been identified.
“Data on Philippine lakes are fragmented,” Dr. Pablo P. Ocampo of the University of the Philippines Limnological Research Station told the participants of the congress. “We hope to start a data base with PlaNet.”
He was referring to the Philippines Lakes Network first conceived in 2003 during the first congress.
Lakes are large, inland body of fresh or salty standing water. The basins are formed by many geological processes, such as buckling of stratified rock into large folds, displacement of large masses of rock by faults, and blocking of valleys by landslides.
The source of lake water is atmospheric precipitation that reaches the lake directly and by means of springs, brooks, and rivers. Lakes form and disappear over the course of varying lengths of geologic time.
They may evaporate, as the climate become more arid, or they may fill up with sediment, leaving a bog of swamp in their place.
In arid regions, where precipitation is slight and evaporation great, lake levels rise and fall with the seasons and sometimes dry up for long periods.
In lakes where evaporation prevents the water from overflowing the basin rims, substances dissolved in the water become concentrated.
In the Philippines, the biggest freshwater lake is Laguna de Bay (covers an area of 90,000 hectares). It is closely followed by Lanao Lake (34,7000 hectares), then Taal Lake (23,400 hectares), and Lake Mainit (14,000 hectares).
Laguna de Bay, Southeast Asia’s second largest lake (after Indonesia’s Lake Toba), borders Metro Manila and is bounded by Rizal province in the north and by Laguna province in the south.
Once part of Manila Bay, the lake was formed through volcanic activity some 25,000 years ago, according to the Philippine Institute of Volcanology and Seismology. Its only outlet is to the Pasig River.
Lake Lanao, the largest in Mindanao, is located in Lanao del Sur. Bordered by 19 municipalities, including Marawi City, it is supplied by six river tributaries.
Sloping gradually towards the southern end where the deepest portion of 112 meters is found, the lake is shallowest at the northern end where the Agus River, its outlet, is located.
Lake Taal, 56 kilometers south of Manila, occupies the crater of an extinct volcano. It is drained by the Pansipit River, which flows south and empties into Balayan Bay near Lemery.
Volcano Island, an uninhabited island, likes in Lake Taal; on the island is Taal Volcano, an active volcano that also has a lake in its crater.
Lake Mainit, in Mindanao, is one of the largest crater lakes in the country. It has 29 tributaries but is drained solely by the Kalinawan River.
The lake undergoes significant flooding on an annual basis resulting in considerable damage to surrounding agricultural lands and communities, and an impediment to the livelihood of local residents.
One of the most important roles of lakes is as source of water for direct human consumption, agriculture, industrial use, and hydropower. Lake Lanao, for instance, is a major source of hydropower.
Another value of lakes: they help control floods. Tonle Sap, the great Lake of Cambodia, is fed in the rainy season by water and sediment from the Mekong River draining the mountainous area of Thailand, Laos and the Chinese border.
As such, the lake – by retaining flood flows – maintains a constant flow regime downstream into Vietnam, preserves water quality there and enhances biological productivity for both the aquatic life of the river and for the human communities in the region.
Lakes are also key components in the landscape that surrounds them. They provide diversity and a focal point for viewing the landscape.
As American author Henry David Thoreau wrote in his Walden: “A lake is the landscape’s most beautiful and expressive feature. It is the earth’s eye; looking into which the beholder measures the depth of his own nature.”
In some instances, lakes are values for their religious importance. Lake Lanao, for instance, is used by the Maranaos for religious practices.
But despite all their uses and significance, lakes are in deep trouble. “Lake ecosystems are threatened by over exploitation, pollution, the proliferation of aquaculture and fisheries structure, the introduction of exotic invasive species, solid and domestic waste,” said Dr. Manuel Bravo of the Ecosystems Research and Development Bureau, a line agency of the Department of Environment and Natural Resources.
Many lakes in the country are shrinking. Take the case of Laguna Lake. As a result of land-use changes (deforestation, quarry activities, urban expansion), about four million tons of suspended solids enter the lake annually, leading to an average net accretion of 0.5 centimeter per year, according to a report from the World Bank.
Deforestation has been cited as one of the primary culprits of siltation in Laguna Lake. “Soil erosion from deforested areas is the main contributor of sediment to the lake,” surmised Dr. Rafael D. Guerrero III, former PCAMRD director.
Lake ecosystems, and the fauna and flora they contain, normally evolve slowly over time. The sudden introduction of new species can quickly upset an ecosystem that has been stable for centuries or even millennia.
“The introduction of tilapia in Lake Buhi and Lake Bato had greatly affected the endemic fish to a point where its population has been drastically reduced,” the Department of Agriculture in Region IV reports.
The decline of the cyprinid flock in Lake is also noteworthy. The introduction of white goby has been implicated in the depletion of most of its cyprinids.
During the second lakes congress, participants agree that now is the time to save the dying lakes of the country.
As PCAMRD Director Cesario Pagdilao suggests, “Momentum is building up in adopting basin-wide approaches for lake management. Land and water ecosystems are interconnected and that an integrated governance mechanism is needed for their management.”
Integrated lake basin management recognizes that lakes and their basins are single mutually dependent ecosystems.
“The sustainable protection, rehabilitation and management of lake and river basins, underlying aquifers, flood plains and associated biodiversity is a crucial concern if we are to reduce the vulnerabilities of the population dependent on these resources,” Pagdilao said.
