An overview of important watershed management issues in rapidly urbanizing metropolitan areas with reference to the Laguna de Bay Region.
Presented at the Workshop on Water, Energy and Environmental Technologies, Philippine Center for Sustainable Development and Environmental Technologies, Manila, Philippines, 10-11 November, 1997.
Author: Michael D. Lee Ph.D.
Introduction
This paper has been prepared for presentation at the inaugural workshop of the newly formed Philippine Center for Sustainable Development and Environmental Technologies (PCSDET). Its objective is to discuss some of the important issues that relate to the management of the Laguna de Bay freshwater lake located on the eastern edge of Metropolitan Manila. It provides some suggestions as to the emphasis that PCSDET activities could take based on a preliminary review of existing issues and was prepared to encourage discussion about the Laguna de Bay and watershed management opportunities and challenges as part of a workshop break-out session on water quality management and water quality assessment.
Physical and environmental context
With its total surface area of about 900 sq. km, Laguna de Bay is the second largest inland body of water in Southeast Asia and the system of watersheds contributing runoff and groundwater to the Lake is complex. A total of 21 tributaries drain into the lake out of six different provinces and a total of 60 municipalities which contain the growing cities of Pasay, San Pablo, Tagaytay, Kalookan, Quezon and Manila (Bacallan, 1997) among others. The total area of the watershed is around 3,820 sq. km and has been significantly modified by land-use change. Back in the early 1980s, agricultural land occupied 52% of the watershed area and urban land 6.5%, proportions that have gone up considerably since then (ILEC, no date). According to the 1995 Laguna de Bay master plan (LLDA, 1995), 1992 urban land-use had grown to occupy 29% of the watershed, agriculture remains at around 52% and the forested area has shrunk to around 5%. This is explained by the fact that much urban expansion on the lowlands has been on rice field areas whereas at the same time, upland forests have been lost to agriculture. The population lives in both large and small settlements widely distributed throughout the catchment area, but with many concentrated on the lowland lake fringe.
Climate conditions in the watershed are highly variable, with a long term average rainfall of around 2,000 mm a year, with four very dry months from December through March, averaging at around 30mm per month, and a distinct rainy season peaking in June-July when monthly rainfall will be over 400mm. This peaky distribution leads to periods of heavy runoff and erosion within the watershed in which suspended and disolved solids and natural and man-made chemicals can be washed in large quantities into streams and rivers or flushed down into groundwater and into the lake. Periodically there are droughts in which the lake level can drop several meters and pollution concentrations can increase markedly. A key issue is the impacts of the first-flush of the early monsoon rains on the lake. These rains, coming after a relatively long dry period and at a time where the land lies most vulnerable to erosion and to the removal of accumulated organic material and sediments to the lake, probably contributes a proportionally high amount of the non-point loading.
The lake itself has a wide range of uses: as a source of water for industry and public supply, navigation and transportation, sightseeing and tourism, recreation (public swimming and sport-fishing) and fisheries. Laguna de Bay is also one of the principal sources of freshwater recharge feeding the Manila Bay aquifer system and the Greater Manila Area (Munasinghe, 1992). The Laguna de Bay is an important fishery for the region, producing some 120,000 metric tons per year, principally Milkfish, White Goby and Therapon (ILEC, no date). Monitoring data has showed that there has been a significant increase of pathogenic microorganisms along the shoreline as population levels in the watershed have grown. This microbial contamination is of particular health concern to fish eaters and bathers in the lake.
Government officials have indicated that it had long been in the minds of planners to use the Laguna de Bay as a future source of drinking water for Manila sometime within the next 30 years (Padolina, personal communication), but that this time was rapidly arriving. Laguna de Bay is currently functioning as a very large, very shallow aerobic wastewater oxidation system for the degradation of oxygen demanding biological waste and as a large sink for organic and inorganic chemicals produced by the industry and urban settlements crowding onto the lakeshore and lowland surrounds. If efforts are not made to coordinate use of the land and control waste generating activities, then by the time the lake is needed for water supply, it could easily become a very large septic system, choked by water hyacinth and algal scum, and largely dead or dying in some of its more highly polluted and hydrologically static sections.
Over 1,500 separate industrial operations can be found in the watershed with many agroindustries, particularly food processing plants, chemical plants and metal works. There is a growing trend to establish government science and light industry parks and tax-free industrial zones in the various watersheds. Data from the Laguna Lake Development Authority (LLDA) suggest that the majority of these facilities drain their wastewater directly to the lake or its tributaries, contributing considerable physical, chemical and biological point pollution to the overall contaminant loading. This is typical for urban areas in developing countries where rapid settlement growth overwhelms systems that were originally developed in colonial times and have not been adequately extended or expanded to match the population increases that have occurred.
According to figures quoted in Bacallan (1997), the pollution loading of Laguna de Bay is fairly evenly divided between agricultural, domestic and industrial sources, each of which contribute between 30 and 40% of the total. Estimates made in the early 1980s indicated that the relative loading of nitrogen and phosphorous in the Lake from point and non-point sources was as follows: non-point sources (agricultural, natural and dispersed settlements) 60%, municipal sewage collection system point sources 25%, industrial waste point sources 15% (ILEC, 1997).
How the balance between these sources of pollution has changed over the last ten or 15 years is unclear at this time. Clearly industrial and urban growth has accelerated around the Lake but also there apparently has been significant growth in the number of towns and the farming population in the upland areas of the watershed to the north and east. Data from the 1980s (Cruz, 1996) showed increasing trends of reverse migration out of Greater Manila and from the lowlands up into the upland areas where encroachment has been occurring onto public land previously dedicated to forestry. Up to 2 million people made this transition nationwide in the first half of the 1980s, often onto relatively steep slopes, aggravating problems of soil erosion and nutrient loss into streams and rivers. Upland population growth is accompanied by construction of unpaved rural roads, a major source of sediment-laden runoff during monsoon storms. Similarly, in the lowlands, urban and industrial expansion is accompanied by major infrastructure projects such as super-highways. For instance, it was announced in June that work would shortly begin on a new four-lane expressway along Laguna de Bay's perimeter shoreline which will likely further spur development along the Lake margins between San Pedro and Taytay along its 33 kilometer length. These developments become important pollution sources for the Laguna de Bay and would need to be addressed as part of any watershed management plan.
Watershed management for Laguna de Bay
As is typical for most large watersheds on the fringe of rapidly expanding urban areas in developing countries, the Laguna de Bay watersheds present a broad range of environmental management challenges. The watersheds are land areas on which multiple resource needs are satisfied – farming, forestry, industrial, commercial, residential and recreational. From the point of view of the environmental aquatic system that the Laguna de Bay represents, many of these resource uses are detrimental to the health of the lake and its potential future use as a municipal water source. At the same time that the land around the lake has become more intensively used and the Lake subject to greater loading of pollutants, the Lake itself and its water quality is becoming all the more valuable and important to protect because there appear to be few alternative water sources available to meet the needs of the Manila going into the 21st century.
Watershed management means addressing two important but fundamentally different modes of pollution – concentrated point pollution and dispersed, broad-based non-point pollution. For example, in the United States, emphasis in urbanized watersheds has historically been on point source control. Since the Water Pollution Control Act of 1948, the US government has been investing considerable amounts of public funds to try and protect the lake and river systems of the United States from the deleterious impacts of water pollution. In the early decades of this act and its subsequent amendments as the Clean Water Act of 1977, US environmental authorities have used permits for discharging point waste and implemented incentive programs for the installation of wastewater treatment systems. These efforts have been very successful in regulating and reducing the levels of contaminants entering US water bodies. However, they have not gone far enough. The 1994 national water quality inventory shows that nearly 40% of surveyed waters in the US remain too polluted for fishing, swimming and other uses. The leading causes of impairment found in the survey include silt, sewage, disease-causing bacteria, fertilizer, toxic metals, oil and grease, the majority of which come from non-point sources within the watersheds of the river or lake systems in question.
It would appear that similar to the US model, the Philippine government has already made important steps to protect the Laguna de Bay from point pollution. The 1995 master plan for sustainable development in the Laguna de Bay Region contains two sub-programs on watershed management and environmental management that provide for water quality monitoring programs on the lake and its tributaries and the implementation of pollution control programs which include the adoption of waste minimization measures by companies, the installation of common wastewater treatment facilities, and the use of biotechnology in pollution control.
Key elements of this point pollution program include:
However, there are still very few on-site treatment systems or public sewerage in the urban areas and very low levels of coverage of sanitation facilities in the rural areas. Where sewer connections exist, they simply provide for a collection and disposal system into the Lake and its tributary rivers rather than a treatment system, the receiving bodies themselves acting like large oxidation systems for the degradation of oxygen demanding organic waste and the gradual destruction of pathogenic organisms. Most of the households around the lake have private septic tank systems but many rural homes do not have even the most basic latrines. In the urbanized areas, graywater is often discharged directly into open ditches running through the communities, moving water and urban runoff directly to the lake. In many cases, septic tanks are allowed to fill and overflow to those same ditches. This particularly occurs during the rainy season where lake levels and groundwater levels are high and little movement of septic tank leachate will occur into the substrate.
The model of water source protection in the United States has been changing recently however, a trend that the Philippines could usefully follow with respect to Laguna de Bay. As of around 1992, the US EPA has moved away from its emphasis on point source pollution control toward a new "Watershed Management Approach" to water quality protection. This approach requires the development at each State level of systematic, five-year programs for point and non-point pollution control and for the reporting of compliance with Clean Water Act and Safe Drinking Water Act regulations using the watershed as a planning unit.
Future watershed management issues
Within the Laguna de Bay watersheds, as with any other, particular emphasis and concern must be placed on the upstream-downstream relationships between land and water resource users. Numerous examples have shown that actors in the contributing watersheds usually have little direct interest or incentives in preserving the quality of the rivers or lakes downstream. This is because they derive little benefit from downstream improvements that result. EPA documents in the US stress that watershed management is the process of planning and working toward an environmentally and economically healthy watershed that benefits all with a stake in it. However, in reality, not all watershed management plans can expect to benefit every party – at the most with many plans the objective should really only be to not unfairly burden or disadvantage any party too much in the process, which would lead to resistance against taking actions. It is unrealistic to expect that every individual or institution would benefit from protecting the Laguna de Bay. While the Greater Manila society as a whole may be better off, there will need to be sacrifices made in terms of individuals and corporations forgoing some personal or collective benefits within a particular watershed to protect downstream property values or lake uses.
There will be many conflicts of interest in the Laguna de Bay catchment area because it is so big. It makes sense, therefore, for the PCSDET to start small and build some early successes working with individual pairings of upstream and downstream actors. This suggests the need to concentrate on a small number of tributaries initially rather than tackle the whole 3,820 sq. km all at once. It is important that those involved with the watershed management activities have a clear view of what the goals are and a clear understanding of the limitations facing managers. Resources are likely to be scarce and matters of enforcement weak which places a premium on simple and cheap technologies and maximum cooperation and willingness to act on behalf of the polluters responsible for watershed deterioration. Watershed management planning for the lake needs to go through an initial period of prioritization, some kind of ranking of water quality concerns and secondly a period of targeting, based on available resources, deciding where to allocate money and effort relative to those priority concerns. Ranking requires clear criteria to be developed which will need to be a mix of environmental concerns (e.g. water quality criteria) and political and social criteria (what do people actually care about). PCSDET staff have indicated that initial watershed efforts may focus on only one of the tributaries contributing to the Laguna de Bay. In particular, it has been suggested that the river that passes through the upscale Ayala neighborhood on route to the Lake be chosen because cleaning this up is a high priority to many of Manila’s VIPs who have homes there and industry is keen to comply with pollution controls. Clearly this may not be the most polluted section of the lake or the tributary which contributes the greatest loading of contaminants to the Lake as a whole, but perpaps makes sense initially if it will help mobilize sufficient resources to develop a pilot project that will show that successful point and non-point pollution management can be achieved in this type of environment.
Whichever tributary is selected for initial management attention, there is a clear and urgent need to develop a list of management alternatives, each of which should be evaluated as to their advantages and disadvantages:
A key rule of thumb to be used in determining watershed management objectives and activities is the assessment of the costs of letting contamination continue versus the costs of preventing it. Of critical importance are the pollutants that prevent or hamper certain productive uses of the water, especially fisheries, industrial uses and municipal uses, with drinking water being at the top of the cleanliness scale. When prioritizing watersheds and watershed activities, not only the character of the watershed itself must be considered but also what it does to the section of the Laguna de Bay into which it discharges. The lake is clearly not homogeneous and different sections will have certain characteristics of mixing, patterns of sedimentation, and capacities for assimilation of the contaminants entering into it through its particular tributary. Thus different sections of the Laguna may be targeted for different uses (e.g. local water supply or higher density of fishery production). It may take several years before scientists and planners can fully understand the surface and subsurface dynamics of the whole watershed draining to the Laguna de Bay however, this should not be an excuse for inaction.
Some appropriate watershed responsibilities for the PCSDET
If the new Philippine Center for Sustainable Development and Environmental Technologies wants to live up to its name, there perhaps isn’t a better or more challenging topic than that of how Manila can continue to meet the water supply needs of its population during the coming millenium. The protection of the Laguna de Bay through watershed management would be just one of the issues that would need to be analysed in this context along with groundwater conjunctive use projects, water conservation technologies and programs, and so forth. It is by no means clear that the lake should be considered as a source of drinking water, given the range and type of pollution and the physical characteristics of the lake. It may also be true that there are other more easily protected sources of water for Manila that could benefit more from investment of scarce resources in their protection more critically than the Laguna de Bay. Regardless, the lake’s very important principal use as a fishery resource means that its watersheds should be systematically managed and is clearly sufficient reason to establish a more comprehensive approach to sustainable pollution control.
Watershed management is all about balancing competing resource interests and in particular, resolving the conflicts between upstream and downstream users of land and the aquatic resources that are affected by their actions. With this firmly in mind, the PCSDET would need to work with the LLDA to usefully, but not exclusively, focus on the following areas:
The center can promote the bigger picture for watershed management to prevent the type of point-source dominated, piecemeal approach to the environment that characterized the early efforts in US environmental aquatic protection, specifically through:
The center can take a lead role in identifying, prioritizing and resolving the important conflicts pertaining to sustainable resource use in the watershed of the Laguna de Bay by working with government departments, communities and the private sector on such issues as:
The center can bring to bear expertise and technologies that have already been developed and used in other watersheds to address similar issues (for example, industrial contamination of California-Mexico border rivers by Mexican assembly plants):
The PCSDET can help the watershed management and lake protection process through assisting in the development of a good Geographic Information System for some or all of the 21 watersheds. One of the fundamentals for an effective watershed management program is a good data set that includes such important elements as:
This data will be very important in identifying high-risk zones and priorities for action. PCSDET can be active in the development and management of a comprehensive Geographic Information System together with faculty from California institutions and De La Salle which each have facilities to analyze remote sensing and produce appropriate map-based analysis of key issues. This is programmed as a future activity in the LLDA master plan but it is unclear whether they have the resources to do so.
The Laguna Lake Development Authority will be a key partner in any watershed activities carried out by the center. The Laguna Lake Development Authority has been in place since 1966 and since 1975 has been given the primary responsibility to promote 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. All watershed activities must be closely coordinated with the LLDA but also the multiplicity of government and non-government agencies that are active in the development of, exploitation of and protection of the Laguna de Bay region. The PCSDET can act as a forum which can regularly bring key parties together who are working for the protection of the Laguna de Bay. It should, however, be sensitive to turf issues and not seek to take on powers or responsibilities that are the province of other institutions, particularly the LLDA and the University of the Philippines at Los Baños.
To function effectively, PCSDET will require secure funding over the coming years. In the short to medium term, it should approach the US EPA for funds to conduct a pilot project to apply and test their Watershed Protection Approach model for statewide point and non-point pollution prevention in the Philippines within the Laguna de Bay watersheds. Funds could be mobilized through California EPA or perhaps the US AEP program of USAID. The center should also approach private sector entities such as the new Ayala-Bechtel-United Utilities consortium for financial asistance, particularly to look at issues of municipal sewage discharge to the Laguna Lake from their service territory and options for more effective wastewater treatment. The Ayala consortium will likely have a vested interest in the outcomes of PCSDET efforts to protect potential future sources of drinking water for capital development and the long-term, sustainable improvement in water supply and sanitation. Other creative partnerships could be developed on issues such as solid waste management, where US companies such as Waste Management Inc or BFI might finance studies or pilot projects that could be carried out through the center and facilitated by California EPA and the US AEP.
Given the size of the watersheds, it is important that as PCSDET gets further into any project to protect the Lake region that it establish a local office or center to act as an appropriate home base for scientific and technical actions. Particularly when it comes to watershed management, spending time in the watersheds will be of great importance, a factor that will be made logistically difficult from a base near downtown Manila. It is suggested that PCSDET arrange to establish some space in the LLDA facility in Laguna province and carry out many of its activities there.
References
J.J. Bacallan, 1997. The race to protect the Laguna de Bay Region. Business and Environment. World Bank. Jan-Feb issue.
Cruz M.C.J., 1996. Population Growth and Land Use Changes in the Philippines. In Rampal S. and Sinding S.W, eds., Population Growth and Environmental Issues, Praeger, 63-71.
David W. P., 1988. Soil and Water Conservation Planning: Policy Issues and Recommendations. Journal of Philippine Development. 15(1): 47-84.
International Lake Environment Committee Foundation for Sustainable Management of World Lakes and Reservoirs. Kusasu, Japan. Lake Database: Laguna de Bay Web-Page: http://www.biwa.or.jp/ilec/database/asi/asi-13.html
Laguna Lake Development Authority, 1995. The Laguna de Bay Master Plan. Final report.
Munasinghe M., 1992. Water Supply and Environmental Management: Developing World Applications. Westview Press.
Padolina (personal communication). Remarks made by Secretary Padolina of the Philippine Department of Science and Technology at the inauguration of the Philippine Center for Sustainable Development and Environmental Technology, November 8, 1997.