| Laguna de Bay | |
|---|---|
| Landsat photo | |
| Location | CALABARZON and Metro Manila |
| Lake type | Crater Lake (theorized)/ Rift Lake |
| Primary inflows | 21 tributaries |
| Primary outflows | Pasig River (via Napindan Channel) |
| Basin countries | Philippines |
| Max. length | 41 km (25 mi) |
| Max. width | 36 km (22 mi) |
| Surface area | about 911 km2 (352 sq mi) |
| Average depth | 2.8 m (9 ft 2 in) |
| Max. depth | 20 m (66 ft) (Diablo pass) |
| Shore length1 | 220 km (140 mi) |
| Surface elevation | less 2 m (6 ft 7 in) |
| Islands | Talim Island, Wonder Island |
| Settlements | Metropolitan Manila and the Provinces of Laguna and Rizal |
| 1 Shore length is not a well-defined measure. | |
Laguna de Bay (Filipino: Lawa ng Bay; English: Lake of Bay) is the largest lake in the Philippines and the third largest freshwater lake in Southeast Asia (in terms of surface area) after Tonle Sap in Cambodia and Lake Toba in Sumatra, Indonesia. It is on the island of Luzon between the provinces of Laguna to the south and Rizal to the north. Metro Manila lies on its western shore. Its surface area is about 911 square kilometres (352 sq mi) with an average depth of only about 2.8 metres (9 ft 2 in) and elevation of about 1 metre (3 ft 3 in) above sea level. The lake is shaped like a stylized 'W', with two peninsulas jutting out from the northern shore. Between these peninsulas, the middle lobe fills the large volcanic Laguna Caldera. Laguna de Bay drains to Manila Bay via the Pasig River. The lake is one of the primary sources of freshwater fish in the country.
There is a large island in the lake, Talim Island, which is under the jurisdiction of the towns of Binangonan and Cardona in Rizal province.
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"Laguna de Bay" is the Old Spanish term for "Lake of Bay". "Laguna" is the Spanish word for "Lake", and Bay (pronounced as bä'ï) is a town in Laguna province, along the south shore of the lake.
In the pre-Hispanic era, the lake was known as "Puliran Kasumuran" (Laguna Copperplate Inscription. 900 AD), and later by "Pulilan" (Vocabulario de Lengua Tagala.1613. Pila, Laguna).
The middle part of Laguna de Bay between Mt. Sembrano and Talim island, is the Laguna Caldera) believed to have been formed by two major volcanic eruptions, around 1 million and 27,000-29,000 years ago. Remnants of its volcanic history are shown by the presence of maars at the southern end of Talim Island and a solfataric field in Jala Jala.[1]
Laguna de Bay is a large shallow freshwater body in the heart of Luzon Island with an aggregate area of about 911 square kilometres (352 sq mi) and a shoreline of 220 kilometres (140 mi). It is considered to be the third largest inland body of water in Southeast Asia. Laguna de Bay is bordered by the province of Laguna in the east, west and southwest, the province of Rizal in the north to northeast, and Metropolitan Manila in the northwest. The southern and eastern portions of Metro Manila occupy a huge portion of its watershed. The lake has an average depth of 2.8 metres (9 ft 2 in) and its excess water is discharged through the Pasig River.[2][3]
The lake is fed by 45,000 square kilometres (17,000 sq mi) of catchment areas and its 21 major tributaries. Among these are the Pagsanjan River which is the source of 35% of the Lake's water, the Sta. Cruz River which is the source of 15% of the Lake's water, the Balanak River, the Marikina River, the Mangangate River, the Tunasan River, the San Pedro River, the Cabuyao River, the San Cristobal River, the San Juan River, the Bay, Calo and Maitem rivers in Bay, the Molawin, Dampalit river, Dampalit, and Pele river, Pele rivers in Los Baños, the Pangil River, the Tanay River, the Morong River, the Siniloan River, and the Sapang Baho River.[4] [5]
The lake is a multipurpose resource. It is a navigation lane for passenger boats, source of water for a nearby hydroelectric power plant, food support for the growing duck industry, aquaculture, recreation, fishery, flood control, source of irrigation water and a "virtual" cistern for domestic, agricultural, and industrial effluents.[2] Because of its importance in the development of the Laguna de Bay Region, unlike in other lakes in the country, its water quality and general condition are closely monitored.[6] This important water resource has been greatly affected by development pressures like population growth, rapid industrialization, and resources allocation.[7]
In order to reduce the flooding along the Pasig River during the rainy season, peak water flows of the Marikina River are diverted through the Manggahan Floodway to Laguna de Bay which then serves as a temporary reservoir.[8] In case the water level on the lake is higher than the Marikina River, the floodway can also reverse the flow.
Government data showed that about 60% of the estimated 8.4 million people residing in the Laguna de Bay Region discharge their solid and liquid wastes indirectly to the lake through its tributaries. A large percentage of these wastes are mainly agricultural while the rest are either domestic or industrial[9] According to DENR (1997), domestic and industrial wastes contribute almost equally at 30% each. Meanwhile, agricultural wastes take up the remaining 40%. In a recent sensitivity waste load model ran by the Laguna Lake Development Authority's (LLDA) Integrated Water Resources Management (IWRM) division, it revealed that 70% of biochemical oxygen demand (BOD) loadings came from households, 19% from industries, and 11% came from land run-off or erosion (LLDA, 2005).
As far as industries and factories are concerned, there are about 1,481 and increase is expected.[3] Of the said figure, about 695 have wastewater treatment facilities. Despite this, the lake is absorbing huge amounts of pollution from these industries in the forms of discharges of industrial cooling water, toxic spills from barges and transport operations, and hazardous chemicals like lead, mercury, aluminum and cyanide.[10] Based from the said figure, 65% are classified as “pollutive” industries.
The hastened agricultural modernization throughout the region took its toll on the lake. This paved the way for massive and intensified use of chemical based fertilizers and pesticides whose residues eventually find their way to the lake basin. These chemicals induce rapid algal growth in the area that depleted oxygen levels in the water. Hence, oxygen available to the lake is being used up thereby depleting the available oxygen for the fish, causing massive fish kills.[11]
As far as domestic wastes are concerned, around 10% of the 4,100 metric tons of waste generated by residents of Metro Manila are dumped into the lake. As reported by the now defunct Metropolitan Manila Waterworks and Sewerage System (MWSS), only 15% of the residents in the area have an effective waste disposal system. Moreover, around 85% of the families living along the shoreline do not have toilets.[7][11]
Because of the problems facing and threatening the potential of the lake, the then-President Ferdinand Marcos signed into law Republic Act (RA) 4850, otherwise known as the law creating LLDA. The LLDA is the main agency tasked to oversee the programs that aimed to develop and protect Laguna Lake. Though it started as a mere quasi–government agency with regulatory and proprietary functions, its charter was strengthened by Presidential Decree (PD) 817 in 1975 and by Executive Order (EO) 927 in 1983 to include environmental protection and jurisdiction over the surface waters of the lake basin. In 1993, by virtue of the devolution, the administrative supervision of the LLDA was transferred to the DENR by EO 149.[12]
On January 29, 2008, the Mamamayan Para sa Pagpapanatili ng Pagpapaunlad ng Lawa ng Laguna (Mapagpala) accused the Laguna Lake Development Authority (LLDA) of the deterioration of Laguna Lake due to multiplication of fish pens beyond the allowable limit.[13]
To realize the objectives of the creation of LLDA, the agency implemented policies to curb the possibility of stressing the lake’s assimilative capacity. The most recent policy was the Environmental User Fee System (EUFS). The EUFS was implemented by virtue of LLDA Board Resolution 22 in 1996. The objective of the policy was to “…(reduce) the pollution loading in to the Laguna de Bay by enjoining all discharges of liquid wastes to internalize the cost of environmental degradation…”. Formally, the said board resolution aptly defined the EUFS as a “market–based” policy instrument aimed at reducing the pollution loading in the lake. As such, companies found to have unusually high concentration of pollutants in their emissions, need to pay fines or lake “user–fees”.
The system encourages companies to invest in and operate pollution prevention and/or abatement systems in their establishment. Applying the "polluter pays principle", the system effects direct accountability for damage inflicted on the integrity of the Laguna de Bay region thereby encouraging individuals and business establishments to internalize into their decision-making process the environmental impacts of their day-to-day activities. The EUFS covers all enterprises in the administrative jurisdiction of LLDA that discharge wastewater in the Laguna de Bay system. These include commercial and industrial establishments; agro-based industries and establishments (such as swine farms and slaughterhouses); clustered dwellings (i.e., residential subdivisions); and domestic households[14]
Under the EUFS, a firm is required to secure a discharge permit which is renewed annually at the LLDA. The discharge permit effectively allows the firm to discharge its wastewater to the lake or through its main tributaries. The discharge permit gives the establishment a legal right to dispose their waste water in the Laguna de Bay region. Wastewater is basically sewage, storm water, and water used around the community, including firms.
Domestic wastewater includes black water, or wastewater from toilets, and gray water, which is wastewater from all sources except toilets. Black water and gray water have different characteristics, but both contain pollutants and disease-causing agents that require monitoring. Nondomestic wastewater is generated by offices, businesses, department stores, restaurants, schools, hospitals, farms, manufacturers, and other commercial, industrial, and institutional entities. Storm water is a nonresidential source and carries trash and other pollutants from streets, as well as pesticides and fertilizers from yards and fields.[15]
According to the Clean Water Act of 2004, the DENR (through the LLDA) shall
“implement a wastewater charge system in all management areas including the Laguna Lake region and Regional Industrial Centers through the collection of wastewater charges/fees. The system shall be established on the basis of payment to the government for discharging wastewater into the water bodies. Wastewater charges shall be established taking into consideration the following: a) to provide strong economic inducement for polluters to modify their production or management processes or to invest in pollution control technology in order to reduce the amount of water pollutants generated; b) to cover the cost of administering water quality management or improvement programs, including the cost of administering the discharge permitting and water pollution charge system; c) reflect damages caused by water pollution on the surrounding environment, including the cost of rehabilitation; d) type of pollutant; e) classification of the receiving water body; and f) other special attributes of the water body.”
The technical aspect regarding the quality of wastewater is given in DENR Administrative Order 1990-35. The order defines the critical water parameters’ value versus the classification of the body of water (e.g., lake or river). Discharge permits are issued by the LLDA only if the wastewater being discharged complied with the said order.
The EUF is paid for the amount of pollution that is discharged into the tributary rivers in the Laguna de Bay region. It is composed of a fixed fee and a variable fee. The fixed fee covers the administrative cost implementing the Environmental Users Fee System and is based on the volume of wastewater that is discharged.
According to LLDA Board Resolution 33, as amended, the fixed fee is different for those firms that discharge wastewater without or with heavy metals.
Wastewater without heavy metals:
| Fee | Volume of Wastewater Discharge |
|---|---|
| PhP 24,000 | More than 150 m3 per day |
| PhP 16,000 | Between 30 and 150 m3 per day |
| PhP 8,000 | Less than 30 m3 per day |
Wastewater with heavy metals:
| Fee | Volume of Wastewater Discharge |
|---|---|
| PhP 12,000 | Less than 150 m3 per day |
| PhP 24,000 | More than 150 m3 per day |
The fixed fee also depends on the volume of wastewater discharged. For a firm that discharges wastewater without heavy metals, the fee is PhP 24,000 if the discharge is more than 150 m3 per day, PhP 16,000 if the discharge is between 30 to 150 m3 per day, and PhP 8,000 if the discharge volume is less than 30 m3 per day. Those firms that discharge wastewater with heavy metals pay higher fixed fees. The fee is PhP 12,000 for a firm that discharge less than 150 m3 of wastewater with heavy metals per day and PhP 24,000 if the discharge is more than 150 m3 per day.
The variable fee is calculated with the reference to the biochemical oxygen demand (BOD5) loading as well as to the volume and concentration of the wastewater being discharged. According to the same policy, the variable fees is PhP 30 per kilogram of total BOD5 when the BOD5 concentration is less than 50 milligrams per liter and PhP 30 per kilogram of total BOD5 when the BOD5 concentration is greater that 50 milligrams per liter.
Laguna lake has had a significant impact on the cultures of the communities that grew up around its shores, ranging from folk medicine to architecture.
For example, the traditional cure for a child constantly experiencing nose bleed in Victoria, Laguna is to have the child submerge his or her head in the lake water at daybreak.[16]
When nipa huts were more common, huts made in the lake area were constructed out of bamboo that would first be cured in the waters of Laguna Lake.[17]
Some experts on the evolution of local mythologies suggest that the legend of Mariang Makiling may have started out as that of the Lady (Ba'i) of Laguna de Bay, before the legend was transmuted to Mount Makiling.[18]
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