‘Whole-of-community approach’, stricter policy implementation sought; Water quality of Laguna Lake’s tributaries continue to deteriorate − LLDA data

By Shane Rachel C. Del Rosario

Laguna de Bay is the country’s largest lake and major source of potable water. But despite its major role in providing livelihood and food to its surrounding cities and amidst the presence of laws and ordinances aiming to protect the water body, waste pollution continues as its biggest threat.

Several studies and data from the Laguna Lake Development Authority (LLDA) shows deteriorating water quality of the lake due to waste pollution.

Established in 1996, LLDA is a quasi-environmental agency that is responsible for the development, preservation, and sustainability of Laguna de Bay and its tributary rivers.

The agency has continuously implemented its water quality monitoring program by conducting monthly assessments which deal with measuring the lake and its tributary rivers’ concentration levels in parameters such as biochemical oxygen demand (BOD), dissolved oxygen (DO), total coliform, nitrate, and pH levels.

They follow the guidelines set by the Department of Environment and Natural Resources (DENR) for classifying water bodies, determining time trends and evaluating stages of deterioration or enhancement in water quality. The data also serves as a basis for establishing initiatives that would prevent, control, or lessen water pollution.

Laguna Lake has 15 monitoring stations and 36 tributary rivers, with a total of 31 shoreline municipalities from Region IV-A CALABARZON and the National Capital Region. These undergo monthly water sampling and are regularly monitored by the LLDA.

These tributary rivers are as vital as the lake’s monitoring stations. They are small streams which flow towards the lake, thus, its condition also affects the overall water quality of Laguna de Bay.

Deteriorating water quality

Using the 2012-2022 annual average reports from LLDA, the water quality of the tributary rivers were analyzed. These include primary parameters such as the BOD, DO, total coliform, nitrate, and pH levels.

In line with the guidelines set by the DENR, each parameter has a corresponding value which sets its water body classification. The classification ranges from Classes A, B, C, and D.

*Note: no data available for Station 8U, 17U, 19U, 22B, 24U, 27 in 2012 and 2013; 20 in 2014; 22C in 2012-2015; 28 from 2012-2017 and 2019; 29 from 2012-2020; and 30 from 2012-2021.

BOD is the amount of oxygen consumed by bacteria and other microorganisms for the decomposition of organic matter, thus, higher BOD indicates lower water quality.

Tributary rivers such as Marikina River (Station 1), Bagumbayan River (Station 2), Buli Creek (Station 3), Mangangate River (Station 4), Tunasan River (Station 5), San Pedro River (Station 6), Biñan River (Station 7), Sta. Rosa River Downstream and Midstream (Station 8 and 8M), Cabuyao River (Station 9), San Cristobal River (Station 10), Manggahan Floodway (Station 25), and Sapang Baho (Station 26) have consistently failed DENR’s water quality guidelines, though Marikina and Sapang Baho River have seen a notable decreasing trend since 2021.

*Note: no data available for Station 8U, 17U, 19U, 22C, 24U, 27 in 2012 and 2013; 20 in 2014; 22B in 2012-2016; 28 from 2012-2017 and 2020-2022; 29 and 30.

DO refers to the amount of oxygen dissolved in the water. Low values ranging from less than two milligrams per liter indicates eutrophication for freshwater lakes. Eutrophication is a phenomenon wherein excess nutrients are present in a water body which can often lead to algal blooms, thus making it difficult for aquatic organisms to survive.

Marikina River (Station 1), Bagumbayan River (Station 2), Buli Creek (Station 3), Mangangate River (Station 4), Tunasan River (Station 5), San Pedro River (Station 6), Cabuyao River (Station 9), San Cristobal River (Station 10), and Sapang Baho River (Station 26) have consistently failed the water quality guidelines for DO while Biñan River, Sta. Rosa River Downstream and Upstream, and the Manggahan Floodway have also decreased its value for DO, thus also failing to meet the given standards in 2022.

*Note: no data available for Station 1 in 2012-2019; 17U, 19U, 22C, 24U, 27 in 2012 and 2013; 20 in 2014-2015; 22B in 2012-2015; 28 from 2012-2017 and 2020-2022; 29 from 2012-2020 and 30 from 2012-2021.

Nitrate levels, when excessive, can lead to excessive growth of algae in water bodies. All tributaries, from 2012 to 2022, were able to comply with the Class A-C guidelines set by the DENR.

*Note: no data available for Station 7 in 2020; 8U,17U, 19U, 22C, 24U, 27 in 2012-2013; 20 in 2014-2015; 22B in 2012-2015; 28 from 2012-2017; 29 from 2012-2020; and 30 from 2012-2021.

Another water quality indicator is phosphate levels. Phosphates play an important role in stimulating the growth of phytoplankton and aquatic plants which serve as food for fish. Excessive amounts, however, would result in over-fertilization of the receiving waters.

As seen in the graph, all tributary rivers consistently failed to meet the water quality guidelines for Classes A to D.

*Note: no data available for Station 7 in 2020; Stations 17-27 from 2012-2019; 28 from 2012-2017; 29 from 2012-2020; and 30 from 2012-2021.

pH levels in water indicate its quality and safety for human consumption. Water with high pH levels may be corrosive and can cause damage to pipes. This can also cause lead and other metals to leach in the water, making it more harmful for humans. Meanwhile, for marine life, unusual levels and changes could disrupt species’ survival and affect their growth and reproductive abilities.

From the years 2012 to 2022, data from LLDA says that all tributary rivers complied with the water quality guidelines for Classes A, B, and C.

*Note: no data available for Station 20 in 2014; Station 22C in 2012-2014; Station 27 in 2012-2013; 28 from 2012-2016; 29 from 2012-2020; and 30 from 2012-2021.

Total coliform levels measure the concentration of bacteria found in the soil, as well as in human and animal waste. It is also a primary indicator of the potability or suitability of water for drinking. All tributary rivers consistently failed the guidelines for Classes A to D.

Urbanization vis-a-vis water quality, pollution

LLDA cites population expansion and urbanization as two of the contributing factors and threats to Laguna Lake’s water quality and ecology.

Water quality parameters such as BOD, DO, and total coliform concentrations indicate levels of waste loadings near the lake as well as its quality. Tributary rivers which consistently fail the guidelines for classes A, B, C, and D are distressed and are found to be in deteriorating condition.

Laguna Lake Tributary Rivers and monitoring stations map. From Laguna Lake Development Authority

These tributaries, including the Bagumbayan River, Tunasan River, and Sapang Baho which failed water quality guidelines on BOD, DO, and total coliform, are situated on the west portion of the lake. They are also found in cities such as Taguig, Marikina, and the municipality of Cainta where built-up area has significantly increased over the years.

A study conducted by Tanchuling and Osorio (2020), stated that Sapang Baho, which was regarded as a pollution hotspot by the LLDA in 2021, is located in an urban area with household communities who directly dump their wastes in the river as well as with the Tunasan River in Muntinlupa. These were proven with the fragments that they collected in the water bodies, which were composed of polyethylene plastics. Polyethylene plastics are the most commonly produced consumer plastic, primarily used for plastic bags and other packaging materials.

Similarly, Diola et al (2020), in their study, reported that Sapang Baho serves as a receptacle for mismanaged wastes and as a tributary river, transports large quantities of microplastics in Laguna de Bay. The researchers also assume that residents near the area directly dispose of domestic wastewater in the said water body.

Lax policies, implementation

In their April 2023 Solid Waste Management Program Performance Audit Report, COA states that the country’s waste generation continues to rise as population, rapid economic growth, and industrialization increase.

More than 20 years after the passage of the Ecological Solid Waste Management Act, solid waste generation in the country has increased from 9.07 million metric tons in 2000 and 16.63 million metric tons in 2022. The agency attributes the situation to the “frail enforcement and compliance with the law due to political, financial, and technical limitations of the local government units”.

In 2018, the Commission on Audit (COA) flagged the municipality of Cainta for failing to practice proper segregation of solid waste due to their lack of strict implementation of the Solid Waste Management Act as well as their Municipal Ordinance No. 2016-03.

Moreover, COA found that the local government failed to establish fully functional Materials Recovery Facilities in all barangays of the municipality, citing lack of proper monitoring by their Municipal Solid Waste Management Board.

LLDA’s laxity in the implementation of its policies units’ waste management initiatives were also seen to contribute to the said problem.

In 2020, the COA flagged the LLDA for failing to collect P144.2 million pesos from industries caught dumping dirty water in the lake. According to the LLDA Memorandum Circular No. 2017-05, an industry is responsible for paying a fee of P5.00 per kilogram if their water discharge is within the effluent standards set by DENR, such as 30 milligram per liter. Otherwise, they are obliged to pay P30.00 per kilogram.

But the LLDA failed to implement this. COA cited an unnamed business establishment whose registered BOD component went as high as 81 milligrams per liter but the LLDA only collected P5.00 per kilogram.

It was also found that until June 2018, the LLDA only collected the fee based on the industry’s self-declared BOD. However, after a reassessment of the discharge from July 1, 2018 to June 30, 2019, it was found that the establishment misdeclared their loading, and yet the agency charged no penalty.

Even in 2022, the COA’s audit report for the agency still cited failure in imposing daily penalty charges to establishments or industries discharging wastewater. Inconsistencies were found in determining the cessation date, and subsequent wastewater collection and inspections take more than a year to five years from the previous collection of samples thus failing to conduct timely interventions for water pollution.

‘Whole-of-community approach’

To resolve these, COA recommends conducting “conscientious monitoring” of the establishments in the Laguna Lake region, as well as conducting regular and timely monitoring of all establishments’ wastewater discharge.

Meanwhile, a provincial environment officer says that a “whole-of-community approach” is also vital in controlling pollution of Laguna de Bay.

“It is everyone’s responsibility to manage the environment, not just the government. People in (the community) are top generators of wastes that have contributed to the pollution of Laguna de Bay,” Marlon Tobias of the Laguna Provincial Environment and Natural Resources Office told the Philippine Information Agency.

With local government units managing the tributary rivers and with urbanization as an unstoppable phenomenon, LLDA, the government, and communities are enjoined to establish actions and initiatives that would help rehabilitate and curb pollution in one of the country’s vital water bodies.


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