LAGUNA DE BAY (LAKE BAY)

Water-hyacinth(Eich hornia crassipes)and fishing boats


Photo: K. oya

A. LOCATION

• Luzon, the Philippines.
• 14:02-14:05N, 121:00-121:05E; 1.8 m above sea level.

B. DESCRIPTION

Laguna de Bay (Lake Bay) is often erroneously called the "Laguna Lake". It is the largest lake in the Philippines. On the lake, there are an island, Talim, and two peninsulas jutting out a long way from the north coast. The lake is considered to have once been a branch of Manila Bay but later became separated from the bay by volcanic deposits and the upheaval of land. Water flows out from the northwestern end of the lake to Manila Bay. Since, the difference of water level between the lake and the sea is so small, the adverse tides occur frequently during the dry season from January to April.
Vast paddy fields, sugar cane fields and coconut plantations spread over the alluvial plain around the lake. Cash products like vegetables, fruits and poultry are also raised for consumption in neighboring big cities as Manila and Quezon City. The Laguna Lake Development Authority established in 1970 is mainly responsible for promoting development and conservation works in the lake and its drainage basin (Q1).

C. PHYSICAL DIMENSIONS (1)

Surface area [km2]	ca. 900
Volume [km3]	ca. 3.2
Maximum depth [m]	7.3
Mean depth [m]	2.8
Water level	Regulated
Length of shoreline [km]	ca. 220
Catchment area [km2]	ca. 3,820

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL (1)

• Sketch map: Fig. ASI-13-01.
• Number of outflowing rivers and channels (name): 1 (Pasig R.).

D2 CLIMATIC (2)

• Climatic data at Manila

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Ann.
Mean temp. [deg C]*1	25.0	25.5	26.8	28.3	28.6	27.9	27.1	27.0	26.9	26.7	25.9	25.2	26.7
Precipitation [mm]*2	23	11	17	32	128	253	414	437	353	195	138	68	2,069

*1 61-year mean. *2 30-year mean.

• Number of hours of bright sunshine (1931-1960): 2,103 hr yr-1.
• Solar radiation (1986): 22.5 MJ m-2 day-1.

Fig. ASI-13-01
Sketch map of the lake (1).

• Water temperature [deg C](3)

Station 1, 1976
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.5	24.6	24.6	26.5	28.2	30.3	28.6	30.6	29.2	30.0	30.2	28.4	25.6
2.0	24.4	25.0	26.3	28.1	29.6	28.3	30.2	28.9	29.0	29.8	28.3	25.4

Fig. ASI-13-02
Vertical distribution of water temperature (1).

• Freezing period: None.
• Mixing type: Polymictic.
• Notes on water mixing and thermocline formation
  As a shallow lake, it is normally well-mixed and the thermocline formation is not seasonal but diurnal.

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](1)

Station 1, 1976
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	0.1	0.2	0.1	0.2	0.6	0.3	-	0.6	0.7	0.5	0.5	0.3

E2 pH: Fig. ASI-13-03.

Fig. ASI-13-03
pH (mean for whole lake), 1973-1977 (1).

E4 DO [mg l-1]: Fig. ASI-13-04 and 05.

Fig. ASI-13-04
DO at 0.5 m depth (mean for whole lake)(1).

Fig. ASI-13-05
Vertical distribution of DO (1).

E5 COD* [mg l-1](Q2)

Determined by K2Cr2O7 method.

1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	9.90	-	32.72	14.25	16.72	22.01	14.31	12.38	7.57	10.12	5.27	-

* Whole lake average.

E7 NITROGEN CONCENTRATION

• NO3-N: Fig. ASI-13-06.

Fig. ASI-13-06
NO3-N (mean for whole lake, 1973-1977)(1).

• Total-N [mg l-1]*(Q2)

1984
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	-	-	1.25	0.96	0.746	1.34	0.72	0.94	0.80	0.499	0.78	-

* Mean for whole lake.

E8 PHOSPHORUS CONCENTRATION

• Inorg-P [micro g l-1]

Fig. ASI-13-07
Inorg-P (average for whole lake, 1973-1977)(1).

E9 CHLORIDE CONCENTRATION [mg l-1](Q2)

1984
Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
-	-	50.76	44.27	75.40	164.66	88.07	85.86	82.77	11.91	76.71	-

F. BIOLOGICAL FEATURES (1)

F1 FLORA

• Floating macrophytes: Eichhornia crassipes.
• Submerged macrophytes
  Vallisneria gigantea, Najas graminea, Hydrilla verticillata.
• Phytoplankton
  Microcystis, Anabaena, Oscillatoria, Closterium, Scenedesmus, Melosira, Stephanodiscus.

F2 FAUNA

• Zooplankton
  Cyclops, Diaptomus, Lernaea cyprinacea, Bosmina, Diaphanosoma, Moina, Keratella, Brachionus, Filinia.
• Benthos: Branchiura, Limnodrilus, Tubifex.
• Fish
  Therapon plumbeus, Glossogobius giurus, Chanos chanos, Megalops cyprinoides, Anabas testudeneus, Hemiramphus sp., Mugil sp.

F3 PRIMARY PRODUCTION RATE [g C m-2 day-1]

1. May-September 1977: 4.4-12.0.

F4 BIOMASS: Fig. ASI-13-08, 09 and 10.

Fig. ASI-13-08
Phytoplankton biomass (average for whole lake, 1973-1977)(1).

Fig. ASI-13-09
Population density of total zooplankton (average for whole lake, 1973- 1977)(1).

Fig. ASI-13-10
Population density of total benthos (average for whole lake, 1973-1977)(1).

F5 FISHERY PRODUCTS (Q1)

• Annual fish catch [metric tons]
  120,000.

F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS (Q2)

Notable increase of Tilapia spp. Significant increase of pathogenic microorganisms along shoreline.

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (Q1, Q2)

	Area [km2]	[%}
Natural landscape
Woody vegetation	908.6	23.8
Herbaceous vegetation	617.0	16.2
Swamp	25.3	0.7
Others	12.9	0.3
Agricultural land	1,984.6	52.0
Residential area	248.3	6.5
Total	3,796.7	99.4

• Main kinds of crops
  Rice, maize, sugarcane, other diversified crops and coconuts.
• Levels of fertilizer application on crop fields: Moderate.
• Trends of change in land use in recent years
  Extensive urbanization especially on western side.

G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE (1, 4)

1975
	No. of persons engaged	Main products or major industries
Primary industry
Agriculture	109,065	Rice, maize, vegetable, fruits
Fisheries	32,828	Milkfish, white goby, therapon
Forestry	2,943
Secondary industry
Manufacturing	376,457	Textile, garment
Mining	5,612
Tertiary industry	951,487

G3 POPULATION IN THE CATCHMENT AREA (Q1)

1980
	Population	density [km-2]	Major cities(population)
Total	2,381,300	712.7	San Pablo (99,000),Calamba, Los Banos

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (Q1)

Source of water, navigation and transportation, sightseeing and tourism, recreation (swimming and sport-fishing) and fisheries.

H2 THE LAKE AS WATER RESOURCE (Q1)

1977
	Use rate [m3 sec-1]
Industrial	8.91
Power plant	46.30

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I2 TOXIC CONTAMINATION (Q2): No information.

I3 EUTROPHICATION

• Nuisance caused by eutrophication: Unusual bloom of Microcystis.
• Nitrogen and phosphorus loadings to the lake [t yr-1](5)

1976
Sources	Industrial	Domestic	Agricultural	Livestock	Others	Total
T-N	190	1,400	772	1,132	448	3,942
T-P	40	197	172	453	80	942

• Supplementary notes (Q2)
  Algal blooms in the 70's not as serious in the 80's, perhaps due to intensive aquaculture which harvests N and P from the lake.

I4 ACIDIFICATION

• Extent of damage (Q2): Not serious.

J. WASTEWATER TREATMENTS

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA (Q2)

f) Severe pollution with no wastewater treatment plants in the immediate vicinity of the lake.

J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF NUTRIENT LOADS (Q2)

	[%]
Non-point sources
Agricultural, natural and
dispersed settlements	60
Point sources
Municipal	25
Industrial	15
Total	100%

J3 SANITARY FACILITIES AND SEWERAGE (Q2)

• Percentage of municipal population in the catchment area provided with
  adequate sanitary facilities (on-site treatment systems) or public sewerage: None.
• Percentage of rural population with adequate sanitary facilities (on-site treatment systems): None.
• Municipal wastewater treatment systems
  No. of tertiary treatment systems: None. No. of secondary treatment systems: None. Primary treatment systems: Individual septic tanks among upper and middle class households; none for lower class households.
• Industrial wastewater treatment systems
  No. of industrial wastewater treatment systems: 40-140 (activated sludge, biogas works, sedimentation ponds, oxidation ponds).

K. IMPROVEMENT WORKS IN THE LAKE

Occasional cleaning of tributaries polluted by settlements.

L. DEVELOPMENT PLANS

Napindan Hydraulic Control Structure in operation since 1985 by MPWH. Manggahan Floodway 80% completed. MPWH Lake Zoning and Management Plan, ongoing implementation by LLDA.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED

1. National Pollution Control Decree, P. D.984 (1976): National Pollution Control Commission.

M2 INSTITUTIONAL MEASURES

1. Laguna Lake Development Authority (1966, as amended by P. D. 813 in 1975), Univ. of Life Complex, Pasig, Metro Manila

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES

1. Institute of Chemistry, University of the Philippines at Los Banos (UPLB)
2. Institute of Biological Sciences-Limnological Research Station, UPLB
3. SEAFDEC, Binangonan Station

N. SOURCES OF DATA

17. Questionnaire filled by Dr. Teodoro B. Baquilat, Laguna Lake Development Authority, Manila.
17. Questionnaire filled by Dr. Marlito Lanzona Cardinas, Institute of Chemistry, University of the Philippines at Los Banos.
1. World Health Organization & Laguna Lake Development Authority(1978) Final Report, Comprehensive Water Quality Management Program Laguna de Bay, Vol.1 (Summary Report). 231 pp. Laguna Lake Development Authority. Manila.
2. Muller, M. J. (1982) Selected Climatic Data for a Global Set of Standard Stations for Vegetation Science. 306 pp. Dr. W. Junk Publishers, the Hague.
3. World Health Organization & Laguna Lake Development Authority (l978) Final Report. Comprehensive Water Quality Management Program Laguna de Bay, Vol. 7 (Limnology of Laguna de Bay), Appendix 2. 370 pp. Laguna Lake Development Authority, Manila.
4. National Census and Statistics Office (l975) Integrated Census of the Population and its Economic Activities. Manila.
5. Fernandez, A. L. (1981) Fundamental Study on Multiobjective Water Resources Planning. 238 pp. In partial fulfillment of the requirements for Master's degree in engineering, Osaka University, Osaka.
6. Annual Report. College of Engineering and Agro-industrial Technology, Vol. 24 (1982) Department of Agrometeorology University of the Philippines at Los Banos, College Laguna.
7. Annual Report, College of Arts and Sciences, Vol. 28 (1986) Institute of Chemistry, Department of Analytical and Environmental Chemistry, University of the Philippines at Los Banos, College Laguna.