Laguna De Bay's Current Problems

Current Problems

Being at the heart of the country’s urban and industrial center, Laguna de Bay is threatened by inevitable price of progress- rapid population growth, land conversion, water pollution, and over fishing.

Rapid population growth

Land conversion

Proliferation of exotic species

Water pollution

Population Trends

1995

LEGEND:

2005

As of 2005, the estimated population in the Laguna de Bay Region is about 13.2 million. It is projected that the population in the lake region will grow at a rate of 2.25 percent per year. The western portion or those areas near Metro Manila will continue to become denser than the eastern portion.

However, the direction of population growth shows that population spreads from Metro Manila towards the towns and cities of Rizal, Laguna, Cavite, and Batangas. There will be a gradual expansion of population towards the eastern and southwestern portion. Moreover, population in the shoreland is likewise increasing. The highest population is projected to occur in Metro Manila and the provinces of Cavite, and Rizal.

1995

LEGEND:

2005

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Land Conversion

The total land area of the Laguna de Bay watershed is approximately 2, 920 sq. km. A major transformation was noted in the region in 1996-2000. During this period, 25 percent of areas for commercial and non-commercial forest and 67 percent for agriculture were greatly reduced to five percent and 52 percent, respectively, as the lake region became more industrialized.

Built-up and industrial areas now account for 29 percent of the total land area. Open unproductive grasslands also grew from eight to 14 percent during the same period. These changes in land use and land cover indicate the occurrence of deforestation which could lead to soil erosion and impair the hydrology of the basin.


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Landsat images (above) showing basic land cover changes in a span of nine years.

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Proliferation of Exotic Species

In the recent years, exotic species of plants and aquatic organisms were introduced into the sub-basins that, in turn, have reached the lake basin. Invasive exotic species compete with native species for food and space.

The Thai catfish Clarias batrachus, displaced the native catfish Clarias macrocephalus, and the golden apple snail Pomacea canaliculata displaced the native snail Pila luzonica.

Janitor fish, a favorite of aquarium hobbyist, became a pest as fishermen complain that the janitor fish not only gobble up the algae in the lake depriving other fish of food, they also destroy fishing nets with their sharp fins.

The Bureau of Animal Industry found that it is high in protein and EMB-DENR said that it may be considered as a component of fish meal.

Collaborative work is now being understaken by the Bureau of Fisheries and Aquatic Resources, Bureau of Animal Fisheries, EMB, University of the Philippines Los Baños and LLDA to understand the biology and assess the ecological impacts of its increasing population.

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Water Pollution

Results of the 1994-2004 water quality monitoring indicated that four out of 15 (27%) rivers draining into the lake are highly polluted in terms of biological oxygen demand (BOD) and dissolved oxygen (DO).

These rivers include San Pedro and San Cristobal in Laguna; Tunasan, Marikina, and Mangangate in Metro Manila; and Sapang Baho in Rizal.

Biochemical oxygen demand (BOD) is a measure of the quantity of oxygen used by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter. Hence, high BOD level implies high presence of microorganisms brought about by pollution.

All the 15 rivers monitored exhibit high fecal contamination exposing to health risk about 2.7 million population.

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