INTRODUCTION

The Laguna Lake Development Authority has been in place since 1966 (Republic Act no. 4850) and since 1975 has been given the primary responsibility to promote the development of the Laguna de Bay region, while providing for environmental management and control, preservation of the quality of life and ecological systems, and the prevention of undue ecological disturbance, deterioration and pollution.

Since the early seventies LLDA has been regularly conducting water quality monitoring of the Laguna de Bay and its tributaries. These routine monitoring activities have been made part of the LLDA program especially when assessing the status of the lake under different circumstances.  

The objectives of the routine LLDA water quality monitoring programs are: 

• To accurately assess the suitability of the lake for all its present and intended beneficial uses;

• To evaluate the impacts of development activities on the lake’s water quality that will serve as important criteria for environmental planning and management.

Routine monitoring programs conducted by LLDA cover different locations, time periods and parameters. However, considering the vast area of Laguna de Bay and the high costs involved, these monitoring programs will inevitably be limited in their coverage, both spatially and temporally.

With the recent set-up of an information system for storage, processing and analysis of environmental data (HYMOS), the presentation of the routine monitoring data can now be automated and further improved. To present the water quality status of the lake and its tributaries on a monthly basis, a Mondriaan-like presentation was developed dubbed the ‘Water Mondriaan’. Its purpose is to provide the policy making body of the authority as well as the various stakeholders through the LLDA website, an immediate and comprehensive overview on selected characteristic water quality parameters at different parts of the water system without suggesting to have detailed spatial information.

The Water Mondriaan is a schematic map of the Laguna de Bay water system, showing the monitoring results in the lake and its tributaries compared with the DENR water quality criteria/water usage & classification for freshwater systems or when absent the LLDA expert opinion. The parameters included, focus on factors of significant ecological, human health and resource use importance or on the processes that are crucial to them:

• oxygen and oxygen demand (%DO, BOD5 and COD)

• bacterial pollution (Total Coliforms, Fecal Coliforms)

• eutrophic level (phosphate, dissolved nitrogen, chlorophyll-a and phytoplankton abundance)

• hazardous substances (oil & grease and on a quarterly basis lead, hexavalent chromium and cadmium)

MONITORING PROGRAMS

Routine monitoring of the water quality of the lake and its tributaries has been in place since 1973. In time, the program has been slightly adjusted regarding spatial and temporal coverage and the number of parameters included. In the figure and table below the present lake and tributary monitoring stations are presented.

* position your cursor over a point to see the location of the station

Assuming that the stations are indicative of their immediate surroundings an overall schematic impression of the water quality status can be obtained. Results will be presented on a monthly basis in a schematized Mondriaan-like representation of the Laguna de Bay as shown in the figure below.

SELECTED PARAMETERS

Oxygen saturation and oxygen demand

The oxygen saturation level indicates the degree of pollution by organic matter, the level of primary production and the level of self purification of the water. The BOD5 expresses the oxygen demand for the biodegradation of organic matter and indicates the risk for low DO saturation levels. Almost 70% of BOD5 loads in the Laguna de Bay are from households and 20% is from industrial origin: the remaining part is from land run-off. COD expresses the total oxygen demand, including the oxidation of all organic matter and reduced inorganic compounds as ammonium. In shallow lakes, excessive BOD5 and COD can cause oxygen depletion and suffocate living resources.

Bacterial pollution

Ideally, a water system should not contain any micro-organisms known to be pathogenic or any bacteria indicative of faecal pollution as it would render the water unsuitable for all sorts of functions. The existence of these micro-organisms can be linked to untreated sewage and sludges, night soil and animal wastes. Exposure to human pathogens via contact with contaminated water or consumption of contaminated shellfish can result in infection and disease. Selected indicator parameters are Total Coliforms and Fecal Coliforms, as these two have been used in the DENR water quality criteria / water usage & classification for freshwater systems.

Eutrophic level

Perhaps the most pressing problem in Laguna de Bay is eutrophication or nutrient enrichment from domestic (some 70 – 80%), agricultural and to a lesser extent from industrial loads. Excessive levels of nutrients such as dissolved nitrogen and phosphate (o-PO4P) increase primary production. At adverse levels, impacts include nuisance algal blooms and oxygen depletion, which suffocate living resources. In addition, total phytoplankton cell counts and chlorophyll-a are presented. The net primary production is also given in relation to the potential fish production in the lake. Phytoplankton refers to microscopic aquatic plants that have a very significant role in aquatic productivity because it provides food and oxygen necessary for the survival of aquatic animals. Chlorophyll-a is the photosynthetic pigment that relates to the total phytoplankton biomass. Phosphate is the only selected parameter that is used in the DENR water quality criteria / water usage & classification for freshwater systems.

Hazardous substances

Hazardous substances, dissolved or suspended in the water column or accumulated in sediments can result in an array of adverse ecological effects. Many of these compounds are suspected carcinogens and/or reproductive toxicants, which can accumulate on the tissue of fish and shellfish, which may then be consumed by humans. The bio-accumulative effects of these compounds on the ecosystem depend on the characteristics of the compound. The three most toxic heavy metals of the LLDA monitoring program were selected: Hexavalent Chromium – Cr(6+), lead - Pb and Cadmium - Cd., all expressed as total concentration in the water phase

Hexavalent chromium is used extensively in metal pickling and plating operations, leather industry as tanning agent and in manufacturing paint and dyes.

Mixed lead and zinc ores account for about 70% of total primary lead production. Lead is also produced from scrap (secondary lead), which accounts for about 35% of the total world lead supply. The largest consumer of lead is the use as an additive in fuels, production of batteries, paints, anti-radiation armour, pesticide formulation, pigments, cable sheeting, alloys and various semi manufacturers.

Cadmium is a trace element in the earth’s crust, which is generally associated with zinc minerals. Cadmium and cadmium compounds are used mainly in nickel / cadmium batteries, as bright yellow pigments in paints and synthetic materials and as stabilizers of synthetic materials. Furthermore, it can be produced as by-product of fertilizer, application and waste-incineration industries.

Oil & grease was selected as it may harm aquatic life by direct contact, by poisoning with various water soluble substances, that may be leached from it or by emulsions which may coat the fish gills or may be swallowed with water and food.

PRESENTATION

The colours in the Water Mondriaan (blue, white, yellow, red, black and grey) represent the specific condition of the water system for a certain period with respect to the selected parameters.

The selected colouring and other details are indicated in the legends, which are specific to each figure. The legends follow the DENR classification for freshwater systems. When classes are described by the same water quality value, they are merged and presented as one colour.

For the other parameters (COD, pathogens, chlorophyll-a, phytoplankton abundance) that cannot be presented through the DENR classification, the legend reflects the LLDA expert opinion and will be expressed in terms of ‘very low’, ‘low’, ‘medium’, ‘high’ and ‘very high’.

The internet provides a powerful tool for sharing and communicating information and will be used to inform the stakeholders on the monthly monitoring results. These results are available through the LLDA website www.llda.gov.ph.

Moreover, in the annual report, which will also be presented on the website, the overview of monthly statements will be incorporated.

SELECTED CLASSIFICATION

The Water Mondriaan has been developed within the Sustainable Development of the Laguna de Bay Environment (SDLBE) project. SDLBE is a project of bilateral co-operation between the Philippines and the Netherlands, supported by a grant from the Netherlands Government for Technical Assistance.