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By Henrylito D. Tacio,
Special Correspondent
LOS BAÑOS, Laguna — When viewed from higher
ground, Laguna Lake — Southeast Asia’s second largest (after
Indonesia’s Lake Toba) — seems like a large basin of silver,
sparkling in the sun, placid, and thinning at the edges.
Recent reports have claimed the famous lake and source of livelihood
for thousands of families, is biologically dead.
But scientists and government officials say
there’s life in Laguna Lake yet. In fact, it is being eyed as a
vital source of Metro Manila’s drinking water. “Laguna Lake is
very much alive,” says an official from the Laguna Lake
Development Authority (LLDA), an agency of the Department of
Environment and Natural Resources (DENR), which maintains
jurisdiction over the lake.
A lake is considered dead, he explained, if it
can no longer sustain aquatic life. But the lake still
continues to provide fish such as bangus, tilapia, kanduli, and biya.
The fact that the lake and its tributaries are
located in the country’s center of urban and industrial
development is a big factor. After all, Laguna Lake straddles
Metro Manila, the whole of Laguna and Rizal, and parts of Batangas,
Cavite and Quezon.
“This makes the lake a major supplier of water
for the provinces that compose the
Cavite-Laguna-Batangas-Rizal-Quezon (Calabarzon) area,” Rivera
writes in her paper, which was presented during the National
Symposium and Awarding Ceremonies for Outstanding Achievements in
Agriculture and Resources Research and Development.
Traditionally, Laguna Lake has been used for the
functions of aquaculture, irrigation, transportation, recreation,
cooling water for machine used in power generation, domestic
cleaning and drinking, and other industrial purposes. But too many
uses are also a bad thing.
“Industrialization poses its own demerits in
connection with the quality upkeep of the lake,” Rivera notes.
The lake, she warns, has become a sink for the waste generated by
the industries located along its periphery.”
This concern has been echoed by the DENR’s
first ever “Philippine Environmental Quality Report.” It
said: “Development pressures like population growth,
industrialization, urbanization and resources utilization are taking
their toll on this important water resource.”
Central role
The Laguna Lake has an estimated area of 90,000
hectares. It has an average depth of 2.8 meters and a
shoreline of 220 kilometers long. The lake has a watershed
area of about 382,000 hectares.
The lake has 21 river tributaries that drain
into it. The Pagsanjan River contributes 35 percent of the
total freshwater that flows into the lake while the Sta. Cruz River
contributes 15 percent. Napindan River is the lake’s only
connection to the historic Pasig River.
Pasig River is the lake’s sole outlet, passing
through a great part of Metro Manila and into the mouth of Manila
Bay. In the dry season (from November to April), when the lake
level is below sea level at 10.5 meters during high tide, backflow
of the Pasig River occurs. In the wet season (from May to
October), the annual mean high water elevation of the lake is 2.5
meters.
“Laguna Lake is a multi-purpose aquatic
resource,” says Dr. Rafael Guerrero III, executive director of the
Philippine Council for Aquatic and Marine Research and Development (PCAMRD).
“The lake is important for its fisheries and as a transport route.
Its water is also used for cooling of industrial plants and
irrigation.”
Toxic waste
Unfortunately, Laguna Lake also serves as a
virtual “catch basin” for the effluents originating from
domestic, agricultural and industrial sources. Every year,
Metro Manila and surrounding provinces and municipalities produce
about 2,000 cubic meters of solvent wastes and 22,000 tons of heavy
metals, including infectious wastes, biological sludges, lubricants,
and intractable wastes. This is according to a study
commissioned by the government for the Toxic and Hazardous Waste
Management Project, funded by the Commission of European
Communities.
The survey found out that toxic and hazardous
waste come mostly from softdrinks, 16 percent; petroleum refineries,
13 percent; office and computing machinery, 11 percent; basic
industrial chemicals, 11 percent; fruit and vegetable canning, eight
percent; malt liquor and malt burning, seven percent; fossil fuel
power plants, six percent; ready-to-wear clothing, five percent;
soaps, perfumes, and cosmetics, four percent; distillation of
spirits, three percent; paints, varnishes, and lacquers, two
percent; and distribution of agricultural chemicals, one percent.
Destruction
Marine species living in the lake are not spared
from destruction. In the past, the lake had 13 kinds of
aquatic plants growing above the water. Now only the lowly
kangkong and the resilient water hyacinth (erroneously called as
water lily) have survived the heavily polluted water of the Laguna
Lake. All bottom-dwelling or rooted plants are generally gone.
Deforestation has also contributed to the dying state of Laguna
Lake. In the late 1970s, the lake’s depth was measured seven
meters. Today, it has gone down to 2.7 meters or even less.
“Soil erosion from deforested areas mainly
contributes to sedimentation of the lake,” Dr. Guerrero laments.
“From all indications, Laguna Lake is destined
to become another classic case of ‘the tragedy of the
commons,’” Celso Roque wrote in a foreword for Laguna de Bay
Problems and Options.
Former Laguna Rep. Rodolfo Tingzon had the same
view: “Laguna Lake represents the most tragic example of the
environmental degradation in this country.”
Conclusion
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