2009 to 2012 Annual Water Quality Report on the Laguna De Bay and Its Tributary Rivers

2009 to 2012 Annual Water Quality Report on the Laguna de Bay and its Tributary Rivers

Department Of Environment And Natural Resources LAGUNA LAKE DEVELOPMENT AUTHORITY Sugar Regulatory Administration (SRA) Compound, North Avenue, Diliman, Quezon City

FOREWORD

This report contains the water quality data on Laguna de Bay (LdB) and its tributary rivers generated by the Environmental Laboratory and Research Division (ELRD) of LLDA, formerly Environmental Quality Management Division (EQMD), from 2009 to 2012 for the LLDA’s Water Quality Monitoring Program which has been on-going since 1973. The results of the assessment of the lake and its tributary rivers’ water quality status during the 4-year monitoring period based on compliance to the Department of Environment and Natural Resources (DENR) Class C Water Quality Criteria as prescribed under DENR Administrative Order (DAO) No.34, Series of 1990, are also presented.

From 2009 to 2011, the five (5) stations monitored in Laguna de Bay were Station I (Central West Bay), Station II (East Bay), Station IV (Central Bay), Station V (Northern West Bay) and Station VIII (South Bay). By 2012, four (4) new monitoring stations were added, namely: Station XV (West Bay- San Pedro), Station XVI (West Bay- Sta Rosa), Station XVII (Central Bay- Fish Sanctuary) and Station XVIII (East Bay- Pagsanjan).

For the monitoring of the Laguna de Bay’s tributaries, LLDA has a total of eighteen (18) stations in 2009 to 2010 that included Marikina, Bagumbayan, Mangangate, Tunasan (Downstream), San Pedro, Cabuyao, San Cristobal, San Juan, Bay, Sta. Cruz, Pagsanjan, Pangil (Downstream), Siniloan, Tanay (Downstream), Morong (Downstream) and Sapang Baho Rivers, Buli Creek, and Manggahan Floodway. To cover the twenty four (24) sub-basins in the Laguna de Bay Region, the monitoring stations in Baras River, Pililla River, Sta. Maria River-Downstream, Pila River, Molawin Creek in Los Baños, Sta. Rosa River-Downstream and Biñan River started in 2011. By 2012, nine (9) additional tributary river stations were monitored located in Mangangate River-Upstream, Tunasan River-Upstream, Sta. Rosa River-Midstream and Upstream, Pangil River-Upstream, Sta. Maria River-Upstream, Jala-jala River, Tanay River- Upstream and Morong River-Upstream. Thus, the number of the water quality monitoring stations at the tributary rivers of LdB in 2012 was thirty four (34).

Throughout the 4-year monitoring period, the water sampling in all lake and tributary river stations was conducted once a month. The analyses of the collected water samples were in accordance with the Standard Methods for the Examination of Water and Wastewater, 21st Edition. 2005. APHA, AWWA, WEF.

This report covers seventeen (17) physico-chemical parameters, three (3) biological parameters, two (2) micro-biological parameters and the results of the lake primary productivity studies. The biological analysis of the water samples in the tributary rivers for phytoplankton counts began only in 2011.

ACKNOWLEDGEMENT

This water quality report on the Laguna de Bay and its tributaries for 2009 to 2012 was prepared by Ireneo G. Bongco (Sr. Science Research Specialist) and Joebeth S. Dalisay (Science Research Specialist II) of the LLDA - Environmental Laboratory and Research Division (ELRD) as part of the LLDA’s Water Quality Monitoring Program.

The support of the following in the preparation and completion of this report is hereby acknowledged:

1. Jocelyn G. Sta. Ana – OIC, ELRD

2. Bileynnie P. Encarnacion – Head, Biology Section - ELRD

3. Dolorita Z. Ravanilla – Head, Chemistry Section – ELRD

4. Marilou D. Cebujano – Head, Microbiology Section – ELRD

Special thanks are also extended to all the technical and support staff of ELRD.

For Public Inquiries, please contact:

Environmental Laboratory and Research Division Tel. No. 286-6143 Laguna Lake Development Authority Department of Environment and Natural Resources Club Manila East, Taytay, Rizal

LAGUNA LAKE AND ITS TRIBUTARY RIVERS SAMPLING STATIONS

iii

LAGUNA LAKE PRIMARY PRODUCTIVITY STUDY SAMPLING STATION

TABLE OF CONTENTS

Page

Foreword i

Acknowledgement ii

Location Map of Laguna Lake and Its Tributary Rivers Sampling Stations iii

Location Map of Laguna Lake Primary Productivity Study Sampling Stations iv

Table of Contents v

List of Tables vii

List of Figures ix

Introduction 1

Physico-chemical Parameters

Alkalinity 2

Ammonia 6

Biochemical Oxygen Demand 10

Calcium Hardness 14

Chemical Oxygen Demand 18

Chloride 22

Dissolved Oxygen 26

Inorganic Phosphate 30

Nitrate 34

Oil and Grease 38

pH 42

Temperature 46

Total Dissolved Solids 50

Page

Total Hardness 54

Total Suspended Solids 58

Transparency 62

Turbidity 64

Biological Parameters

Phytoplankton 68

Zooplankton 72

Benthos 74

Microbiological Parameters

Total Coliform 76

Fecal Coliform 80

Net Primary Productivity of Laguna de Bay 84

Summary 86

Methods of Analysis 87

DENR Administrative Order No.34 88

References 90

LIST OF TABLES

Laguna de Bay and Its Tributary Rivers Page

Physico-chemical Parameters

Alkalinity 2-3

Ammonia 6-7

Biochemical Oxygen Demand 10-11

Calcium Hardness 14-15

Chemical Oxygen Demand 18-19

Chloride 22-23

Dissolved Oxygen 26-27

Inorganic Phosphate 30-31

Nitrate 34-35

Oil and Grease 38-39

pH 42-43

Temperature 46-47

Total Dissolved Solids 50-51

Total Hardness 54-55

Total Suspended Solids 58-59

Transparency 62

Turbidity 64-65

Biological Parameters

Phytoplankton 68-69

Zooplankton 72

Benthos 74

vii

Page

Microbiological Parameters

Total Coliform 76-77

Fecal Coliform 80-81

Net Primary Productivity 84

viii

LIST OF FIGURES

Page

1. Location Map of Laguna de Bay and its Tributary Rivers Sampling Stations iii

2. Location Map of Laguna Lake Primary Productivity Study iv

3. Graphical Presentation

Physico-chemical Parameters

Alkalinity 2 & 4

Ammonia 6 & 8

Biochemical Oxygen Demand 10 & 12

Calcium Hardness 14 & 16

Chemical Oxygen Demand 18 & 20

Chloride 22 & 24

Dissolved Oxygen 26 & 28

Inorganic Phosphate 30 & 32

Nitrate 34 & 36

Oil and Grease 38 & 40

pH 42 & 44

Temperature 46 & 48

Total Dissolved Solids 50 & 52

Total Hardness 54 & 56

Total Suspended Solids 58 & 60

Transparency 62

Turbidity 64 & 66

Page

Biological Parameters

Phytoplankton 68 & 70

Zooplankton 72

Benthos 74

Microbiological Parameters

Total Coliform 76 & 78

Fecal Coliform 80 & 82

Net Primary Productivity 84

INTRODUCTION

Laguna de Bay, with a total surface area of 900 square kilometres (km2), is the biggest lake and one of the most important inland bodies of water in the Philippines. This almost heart-shaped lake, located 13o55‘ to 14o50‘ N latitude and 20o50‘ to 121o45‘ E longitude at 15 kilometers (kms.) southeast of Manila, has three (3) distinct bays, namely: West Bay, Central Bay and East Bay. Its southernmost portion is called the South Bay. Although shallow with an average depth of only 2.5 meters, the lake‘s water holding capacity is estimated at 2.19 billion cubic meters (m3). The lake‘s watershed area of 3,820 square kilometers straddles the whole provinces of Rizal and Laguna, and some towns in Batangas, Cavite, Quezon and cities in Metro Manila. Twenty-one (21) major tributary river systems flow into the lake aside from other relatively small rivers and streams (Tongson, E. T. et al., 2012). The lake‘s only outlet is the Napindan Channel which is connected to Manila Bay via the Pasig River. Seawater backflow has been a natural phenomenon in the lake and it took place in some years in the past. This happens in the lake not every year but occasionally in summer months whenever the lake level is lower than in Manila Bay. As the Pasig River reverses its flow during the entry of saltwater due to the effect of tidal fluctuation in Manila Bay, the salinity of the water in the lake increases.

As a multi use water resource, Laguna Bay is used as source of irrigation water, industrial cooling water, hydroelectric power generation, transport route, source of animal feed, a venue for recreation, source of fish supply and source of domestic water supply. The National Statistics Office (NSO) reported that as of 2007, the total population around the lake was about 14.4 million. To ensure the viability of this vital resource, support is needed from the various lake stakeholders and other parties interested in its sustainable use. Likewise, proper management of the lake and its watershed areas must be intensified and sustained for environmentally sound resources conservation.

From 1975 to 1977, a study was jointly undertaken by the World Health Organization (WHO) and the Laguna Lake Development Authority (LLDA) which included benchmarking of important water parameters and environmental indicators through the conduct of a Comprehensive Water Quality Management Program of Laguna Bay. Realizing the usefulness of having available water quality information on Laguna de Bay and its tributary rivers, LLDA has continuously implemented its water quality monitoring program since the 1970‘s with the following objectives:

1) To accurately assess the suitability of the lake for all its present and intended beneficial uses, and

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

LAGUNA DE BAY Alkalinity, mg CaCO3/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 97 101 82 97 Stn. II (East Bay) 87 91 72 84 Stn. IV (Central Bay) 96 102 84 93 Stn. V (Northern West Bay) 101 104 85 94 Stn. VIII (South Bay) 100 105 86 93 Stn. XV San Pedro (West Bay) * * * 91 Stn. XVI Sta Rosa (West Bay) * * * 89 Stn. XVII Fish Sanctuary (Central Bay) * * * 90 Stn. XVIII Pagsanjan (East Bay) * * * 79

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Depth - Stn. I - composite of 0.5 and 2.0 m. Stn. XV - composite of 0.5 and 2.0 m. Stn. II - composite of 0.5 and 2.0 m. Stn. XVI - composite of 0.5 and 2.0 m. Stn. IV - 0.5 m. Stn. XVII - composite of 0.5 and 2.0 m. Stn. V - 0.5 m. Stn. XVIII - composite of 0.5 and 2.0 m. Stn. VIII - composite of 0.5 and 2.0 m.

Sampling Frequency - Once a month

DENR Class C criterion for Alkalinity - none

B. Graphs

TRIBUTARY RIVERS Alkalinity, mg CaCO3/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 175 167 152 156 2 Bagumbayan River (Taguig) 436 446 282 256 3 Buli Creek (Taguig) 395 415 313 249 Mangangate River 4 (Muntinlupa) -Downstream 363 328 239 182 Mangangate River 4U (Muntinlupa) -Upstream * * * 166 Tunasan River (Muntinlupa) 5 -Downstream 327 362 312 300 Tunasan River (Muntinlupa) 5U -Upstream * * * 193 6 San Pedro River (T2) 307 345 330 290 7 Biñan River * * 253 254 Sta. Rosa River - 8 Downstream * * 297 242 Notes: 8M Sta. Rosa River - Midstream * * * 203 8U Sta. Rosa River - Upstream * * * 171 Sampling Frequency - Once a month 9 Cabuyao River 299 294 289 230 DENR Class C criterion for 10 San Cristobal River (T3) 249 252 252 197 Alkalinity - none 11 San Juan River (T5) 186 148 156 144 12 Molawin Creek (Los Baños) * * 164 187 * No sampling done 13 Bay River (T9) 255 225 222 188 14 Pila River * * 249 252 15 Sta. Cruz River (T6) 109 115 96 127 16 Pagsanjan River (T8) 60 93 42 109 17 Pangil River - Downstream 51 74 49 74 17U Pangil River - Upstream * * * 83 18 Siniloan River 67 86 48 79 Sta. Maria River - 19 Downstream * * 80 87 19U Sta. Maria River - Upstream * * * 85 20 Jala-jala River * * * 81 21 Pililla River * * 112 130 22 Tanay River - Downstream 232 216 187 172 22U Tanay River - Upstream * * * 167 23 Baras River * * 112 132 24 Morong River - Downstream 277 246 217 239 24U Morong River - Upstream * * * 229 Manggahan Floodway 25 (Taytay) 184 182 159 165 26 Sapang Baho River (Cainta) 203 190 170 161

B. Graphs: TRIBUTARY RIVERS Alkalinity 500

450

400

350

300

250 mg/L 200

150

100

0 2009 2010 2011 2012

Year 1 Marikina River 2 Bagumbayan River (Taguig) 3 Buli Creek (Taguig) 4 Mangangate River (Muntinlupa) -Downstream 4U Mangangate River (Muntinlupa) -Upstream 5 Tunasan River (Muntinlupa) -Downstream 5U Tunasan River (Muntinlupa) -Upstream 6 San Pedro River (T2) 7 Biñan River 8 Sta. Rosa River - Downstream 8M Sta. Rosa River - Midstream 8U Sta. Rosa River - Upstream 9 Cabuyao River 10 San Cristobal River (T3) 11 San Juan River (T5) 12 Molawin Creek (Los Baños) 13 Bay River (T9) 14 Pila River 15 Sta. Cruz River (T6) 16 Pagsanjan River (T8) 17 Pangil River - Downstream 17U Pangil River - Upstream 18 Siniloan River 19 Sta. Maria River - Downstream 19U Sta. Maria River - Upstream 20 Jala-jala River 21 Pililla River 22 Tanay River - Downstream 22U Tanay River - Upstream 23 Baras River 24 Morong River - Downstream 24U Morong River - Upstream 25 Manggahan Floodway (Taytay) 26 Sapang Baho River (Cainta)

ALKALINITY

Alkalinity is a measure of the water‘s capacity to neutralize acids and bases thereby maintaining a fairly stable pH. It is also referred to as the acid neutralizing capacity, and sometimes the buffering capacity. Alkalinity of natural waters is due primarily to the presence of weak acid salts although strong bases may also contribute in extreme environments. Bicarbonates represent the major form of alkalinity in natural waters and its source is the partitioning of carbon dioxide (CO2) from the atmosphere and the weathering of carbonate minerals in rocks and soil. Other salts of weak acids, such as borate, silicates, ammonia, phosphates, and organic bases from natural organic matter, may be present in small amounts. Alkalinity is reported as mg/L CaCO3 since most alkalinity is derived from the weathering of carbonate minerals (http://www.whitman.edu/chemistry/edusolns_software/ AlkalinityBackground.pdf). . Alkalinity in natural levels is beneficial to all organisms that depend on water because it helps prevent acidic water (pH < 5) by resisting a change in pH that is harmful to humans, wildlife, and aquatic organisms (http://serc.carleton.edu/sp/mnstep/activities/ 38045.html).

For protection of aquatic life, the buffering capacity should be at least 20 mg/L CaCO3. If alkalinity is naturally low, (less than 20 mg/L) there can be no greater than a 25% reduction in alkalinity (Source: http://www.wilkes.edu/pages/3746.asp). By maintaining at least 20 mg/L CaCO3, the buffering system of the water is preserved which is an important factor to aquatic life since fluctuation of the pH is prevented (LLDA, 1997).

Under DENR Administrative Order (DAO) No. 34, there is no set Class C criterion for alkalinity. From 2009 to 2012, the annual average alkalinity levels in the lake ranged from 82 mg/L CaCO3 (in Stn I - Central West Bay in 2011) to 105 mg/l CaCO3 (in Stn. VIII - South Bay in 2010). In the tributary rivers, the computed annual average alkalinity levels ranged from 42 mg/L CaCO3 (in Stn 16 - Pagsanjan River in 2011) to 446 mg/l CaCO3 (in Stn. 2 – Bagumbayan River in 2010).

LAGUNA DE BAY Ammonia, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 0.044 0.068 0.171 0.162 Stn. II (East Bay) 0.013 0.034 0.038 0.146 Stn. IV (Central Bay) 0.025 0.042 0.060 0.043 Stn. V (Northern West Bay) 0.025 0.055 0.150 0.287 Stn. VIII (South Bay) 0.024 0.032 0.047 0.060 Stn. XV San Pedro (West Bay) * * * 0.045 Stn. XVI Sta Rosa (West Bay) * * * 0.053 Stn. XVII Fish Sanctuary (Central Bay) * * * 0.048 Stn. XVIII Pagsanjan (East Bay) * * * 0.057

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Ammonia - none

B. Graphs

TRIBUTARY RIVERS Ammonia, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 2.71 4.21 2.07 2.85 2 Bagumbayan River (Taguig) 8.25 33.30 5.10 5.53 3 Buli Creek (Taguig) 7.99 23.58 4.84 5.86 Mangangate River 4 (Muntinlupa) -Downstream 5.70 14.90 4.41 3.71 Mangangate River 4U (Muntinlupa) -Upstream * * * 3.81 Tunasan River (Muntinlupa) 5 -Downstream 5.29 6.87 2.74 5.22 Tunasan River (Muntinlupa) 5U -Upstream * * * 1.34 6 San Pedro River (T2) 6.25 10.99 3.79 5.09 7 Biñan River * * 2.71 4.24 Sta. Rosa River - 8 Downstream * * 2.66 2.88 Notes: 8M Sta. Rosa River - Midstream * * * 2.08 8U Sta. Rosa River - Upstream * * * 0.94 Sampling Frequency - Once a month 9 Cabuyao River 2.46 4.63 3.71 4.03 DENR Class C criterion for 10 San Cristobal River (T3) 0.38 0.32 0.26 0.21 Ammonia - none 11 San Juan River (T5) 0.72 0.81 0.74 0.48 12 Molawin Creek (Los Baños) * * 0.19 0.28 * No sampling done 13 Bay River (T9) 0.09 0.10 0.12 0.11 14 Pila River * * 0.13 0.20 15 Sta. Cruz River (T6) 0.21 0.14 0.15 0.27 16 Pagsanjan River (T8) 0.07 0.04 0.09 0.07 17 Pangil River - Downstream 0.06 0.11 0.10 0.13 17U Pangil River - Upstream * * * 0.06 18 Siniloan River 0.71 1.31 0.42 1.00 Sta. Maria River - 19 Downstream * * 0.09 0.24 19U Sta. Maria River - Upstream * * * 0.06 20 Jala-jala River * * * 0.12 21 Pililla River * * 0.32 0.55 22 Tanay River - Downstream 0.53 0.44 0.81 0.40 22U Tanay River - Upstream * * * 0.10 23 Baras River * * 0.81 0.40 24 Morong River - Downstream 2.34 4.45 1.81 2.48 24U Morong River - Upstream * * * 3.16 Manggahan Floodway 25 (Taytay) 2.27 4.35 2.74 3.12 26 Sapang Baho River (Cainta) 3.26 5.61 3.05 3.65

B. Graphs:

TRIBUTARY RIVERS Ammonia

35.00

30.00

25.00

20.00

mg/L 15.00

10.00

5.00

0.00 2009 2010 2011 2012 Year

1 Marikina River 2 Bagumbayan River (Taguig) 3 Buli Creek (Taguig) 4 Mangangate River (Muntinlupa) -Downstream 4U Mangangate River (Muntinlupa) -Upstream 5 Tunasan River (Muntinlupa) -Downstream 5U Tunasan River (Muntinlupa) -Upstream 6 San Pedro River (T2) 7 Biñan River 8 Sta. Rosa River - Downstream 8M Sta. Rosa River - Midstream 8U Sta. Rosa River - Upstream 9 Cabuyao River 10 San Cristobal River (T3) 11 San Juan River (T5) 12 Molawin Creek (Los Baños) 13 Bay River (T9) 14 Pila River 15 Sta. Cruz River (T6) 16 Pagsanjan River (T8) 17 Pangil River - Downstream 17U Pangil River - Upstream 18 Siniloan River 19 Sta. Maria River - Downstream 19U Sta. Maria River - Upstream 20 Jala-jala River 21 Pililla River 22 Tanay River - Downstream 22U Tanay River - Upstream 23 Baras River 24 Morong River - Downstream 24U Morong River - Upstream 25 Manggahan Floodway (Taytay) 26 Sapang Baho River (Cainta)

AMMONIA

Ammonia is a colorless gas with irritating odor. In unpolluted water, trace amounts of ammonia are present from the reduction of atmospheric nitrogen by aquatic microorganisms. Ammonia can be produced naturally from the breakdown of organic matter and is excreted by fish as a nitrogenous waste product. In fish, ammonia is a by- product of protein metabolism and is primarily excreted across the gill membranes, with a small amount excreted in the urine.

Ammonia is a toxic compound that can adversely affect fish health. When dissolved in + surface water, ammonia exists in two forms: NH3 (unionized) and NH4 (ionized). Total ammonia is therefore the sum of the two (2) forms. Ionized ammonia does not easily cross fish gills and is less bioavailable than the unionized form. The unionized form (NH3) can cross from water into fish, and once inside, some converts to the ionized form + (NH4 ), which then causes cellular damage (Francis-Floyd 2009; U.S. EPA, 1989 as cited in http://www.nature.org/cs/groups/webcontent/@web/@alaska/documents/ document/prd_026308.pdf ).The nature and degree of toxicity depends on many factors, including the chemical form of ammonia, the pH and temperature of the water, the length of exposure, and the life stage of the exposed fish. As pH increases, the toxicity of ammonia increases because the relative proportion of unionized ammonia increases. (http://www.nature.org/cs/ groups/ webcontent/@web/@alaska/ documents/document/ prd_026308.pdf).

For the protection of freshwater aquatic life, a level of 0.02 mg/L unionized ammonia (NH3) should not be exceeded (U.S. EPA Environmental Studies Board, 1973 as cited in LLDA, 1997).

DAO 34 has no Class C criterion for ammonia. The highest annual average ammonia concentration in the lake from 2009 to 2012 was in Stn. V – Northern West Bay at 0.287 mg/L in 2012 while the lowest was in Stn. II – East Bay at 0.013 mg/L in 2009.

Among the tributary river stations, Stn. 2 in Bagumbayan River recorded the highest annual average ammonia concentration at 33.30 mg/L in 2010. On the other hand, the lowest annual average ammonia level was obtained in Pagsanjan River in 2010 at 0.04 mg/L. From the computed annual average ammonia concentrations in the tributary rivers from 2009 to 2012, it appeared that those stations with high levels of more than 1 mg/L are mostly located in the West Bay, specifically, Stns. 1, 2, 3, 4, 4U, 5, 5U, 6, 7, 8, 8M, 9, 25 and 26. The other river stations that also yielded relatively high annual average ammonia concentrations were both in Morong River at the Central Bay, namely: Stn. 24 at the downstream from 2009 to 2012, and Stn. 24U at the upstream in 2012.

LAGUNA DE BAY Biochemical Oxygen Demand, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 1 6 3 2 Stn. II (East Bay) 1 5 2 1 Stn. IV (Central Bay) 2 4 2 2 Stn. V (Northern West Bay) 2 5 3 2 Stn. VIII (South Bay) 2 5 2 2 Stn. XV San Pedro (West Bay) * * * 2 Stn. XVI Sta Rosa (West Bay) * * * 2 Stn. XVII Fish Sanctuary (Central Bay) * * * 2 Stn. XVIII Pagsanjan (East Bay) * * * 2

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for BOD - 7.0 mg/l

B. Graphs

LAGUNA DE BAY Biochemical Oxygen Demand (BOD)

mg/l 3

0 2009 2010 2011 2012

Stn. I (Central West Bay) Stn. II (East Bay) Years Stn. IV (Central Bay) Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay) DENR Class C Criterion

TRIBUTARY RIVERS Biochemical Oxygen Demand, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 13 25 12 12 2 Bagumbayan River (Taguig) 60 238 85 64 3 Buli Creek (Taguig) 72 161 136 124 Mangangate River 4 (Muntinlupa) -Downstream 20 42 35 22 Mangangate River 4U (Muntinlupa) -Upstream * * * 11 Tunasan River (Muntinlupa) 5 -Downstream 184 159 129 141 Tunasan River (Muntinlupa) 5U -Upstream * * * 5 6 San Pedro River (T2) 16 18 24 23 7 Biñan River * * 24 21 Sta. Rosa River - 8 Downstream * * 18 16 Notes: 8M Sta. Rosa River - Midstream * * * 14 8U Sta. Rosa River - Upstream * * * 7 Sampling Frequency - Once a month 9 Cabuyao River 11 14 20 17 DENR Class C criterion for BOD - 10 San Cristobal River (T3) 33 78 63 33 7.0 mg/l (for annual average) 11 San Juan River (T5) 9 5 9 4 12 Molawin Creek (Los Baños) * * 4 3 * No sampling done 13 Bay River (T9) 3 4 3 2 14 Pila River * * 3 3 15 Sta. Cruz River (T6) 3 3 3 2 16 Pagsanjan River (T8) 1 3 2 2 17 Pangil River - Downstream 2 5 2 2 17U Pangil River - Upstream * * * 2 18 Siniloan River 3 7 2 3 Sta. Maria River - 19 Downstream * * 3 2 19U Sta. Maria River - Upstream * * * 1 20 Jala-jala River * * * 3 21 Pililla River * * 3 3 22 Tanay River - Downstream 4 4 3 3 22U Tanay River - Upstream * * * 2 23 Baras River * * 6 5 24 Morong River - Downstream 8 13 20 14 24U Morong River - Upstream * * * 15 Manggahan Floodway 25 (Taytay) 7 14 11 11 26 Sapang Baho River (Cainta) 13 17 15 13

B. Graphs:

TRIBUTARY RIVERS Biochemical Oxygen Demand 250

200

150 mg/L 100

0 2009 2010 2011 2012 Year 1 Marikina River 2 Bagumbayan River (Taguig) 3 Buli Creek (Taguig) 4 Mangangate River (Muntinlupa) -Downstream 4U Mangangate River (Muntinlupa) -Upstream 5 Tunasan River (Muntinlupa) -Downstream 5U Tunasan River (Muntinlupa) -Upstream 6 San Pedro River (T2) 7 Biñan River 8 Sta. Rosa River - Downstream 8M Sta. Rosa River - Midstream 8U Sta. Rosa River - Upstream 9 Cabuyao River 10 San Cristobal River (T3) 11 San Juan River (T5) 12 Molawin Creek (Los Baños) 13 Bay River (T9) 14 Pila River 15 Sta. Cruz River (T6) 16 Pagsanjan River (T8) 17 Pangil River - Downstream 17U Pangil River - Upstream 18 Siniloan River 19 Sta. Maria River - Downstream 19U Sta. Maria River - Upstream 20 Jala-jala River 21 Pililla River 22 Tanay River - Downstream 22U Tanay River - Upstream 23 Baras River 24 Morong River - Downstream 24U Morong River - Upstream 25 Manggahan Floodway (Taytay) 26 Sapang Baho River (Cainta) DENR Class C Criterion

BIOCHEMICAL OXYGEN DEMAND

Biological Oxygen Demand (BOD) is the amount of oxygen required by microorganisms for stabilizing biologically decomposable organic matter (carbonaceous) in water under aerobic conditions. The test is used to determine the pollution load of wastewater, the degree of pollution and the efficiency of wastewater treatment methods (http://ces.iisc.ernet.in/energy/monograph1/Methpage1.html). BOD5 is calculated by measuring the amount of dissolved oxygen in a water sample when it is collected, then keeping the sample at 20°C for five days and measuring dissolved oxygen again. The value of the five-day sample is then subtracted from that of the original to get a BOD result in mg/L. High BOD levels can be associated with organic pollution, such as sewage. High levels can also result when nutrient enrichment causes excessive growth and decay of algae and aquatic plants (http://row.nku.edu/index.php?option= com_content&view= article&id= 84&Itemid=74). BOD will not directly harm the aquatic organisms because it is not a pollutant. BOD exerts an indirect effect only when dissolved oxygen of the water is reduced to levels that are unfavorable to aquatic life. (LLDA, 1997).

The DENR Class C water quality criterion for BOD set at 7 mg/L was complied in all of the monitored lake stations from 2009 to 2012 based on the computed annual average BOD concentrations.

The results of the water quality monitoring in the tributary rivers from 2009 to 2012 showed that annual average BOD concentrations ranged from 1 mg/L (noted in Pagsanjan River station in 2009 and in Sta. Maria River – Upstream station in 2012) to 238 mg/L (recorded in Bagumbayan River station in 2010). It was observed that out of the 34 tributary river stations monitored, only 17 stations (Stns. 5u, 8u,12, 13, 14, 15, 16, 17, 17U, 18, 19, 19U, 20, 21, 22, 22U and 23) had all of the BOD annual averages conformed to the DENR Class C criterion. Those stations whose annual average BOD always exceeded the criterion were mostly in the West Bay area, namely: Stns. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 26.

LAGUNA DE BAY Calcium Hardness, mg CaCO3/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 37 62 39 36 Stn. II (East Bay) 33 46 31 31 Stn. IV (Central Bay) 35 58 39 37 Stn. V (Northern West Bay) 42 64 38 43 Stn. VIII (South Bay) 42 49 38 38 Stn. XV San Pedro (West Bay) * * * 47 Stn. XVI Sta Rosa (West Bay) * * * 42 Stn. XVII Fish Sanctuary (Central Bay) * * * 43 Stn. XVIII Pagsanjan (East Bay) * * * 37

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Calcium Hardness - none

B. Graphs

LAGUNA DE BAY Calcium Hardness

65 60 55 50 45

40 /L

3 35 30 25 20

mg CaCO 15 10 5 0 2009 2010 2011 2012

Stn. I (Central West Bay) Stn. II (East Bay)Years Stn. IV (Central Bay) Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay)

Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay)

TRIBUTARY RIVERS Calcium Hardness, mg CaCO3/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 85 90 88 91 2 Bagumbayan River (Taguig) 116 130 89 76 3 Buli Creek (Taguig) 95 99 75 76 Mangangate River 4 (Muntinlupa) -Downstream 90 97 76 73 Mangangate River 4U (Muntinlupa) -Upstream * * * 76 Tunasan River (Muntinlupa) 5 -Downstream 101 86 76 99 Tunasan River (Muntinlupa) 5U -Upstream * * * 82 6 San Pedro River (T2) 93 100 98 104 7 Biñan River * * 87 90 Sta. Rosa River - 8 Downstream * * 99 101 Notes: 8M Sta. Rosa River - Midstream * * * 82 8U Sta. Rosa River - Upstream * * * 77 Sampling Frequency - Once a month 9 Cabuyao River 89 100 98 86 DENR Class C criterion for Calcium 10 San Cristobal River (T3) 87 90 79 97 Hardness - none 11 San Juan River (T5) 85 97 83 91 12 Molawin Creek (Los Baños) * * 70 75 * No sampling done 13 Bay River (T9) 82 82 81 77 14 Pila River * * 42 67 15 Sta. Cruz River (T6) 41 50 34 59 16 Pagsanjan River (T8) 30 42 18 52 17 Pangil River - Downstream 20 36 23 52 17U Pangil River - Upstream * * * 50 18 Siniloan River 24 42 22 42 Sta. Maria River - 19 Downstream * * 45 60 19U Sta. Maria River - Upstream * * * 53 20 Jala-jala River * * * 134 21 Pililla River * * 60 142 22 Tanay River - Downstream 111 90 120 118 22U Tanay River - Upstream * * * 114 23 Baras River * * 60 79 24 Morong River - Downstream 127 111 122 133 24U Morong River - Upstream * * * 131 Manggahan Floodway 25 (Taytay) 82 88 82 89 26 Sapang Baho River (Cainta) 84 90 84 81

B. Graphs:

TRIBUTARY RIVERS Calcium Hardness 160

140

120

100

80 mg/L

CALCIUM HARDNESS

Calcium Hardness is caused by the presence of calcium ions in the water. The presence of calcium in water results from passage through or over deposits of limestone, dolomite, gypsum and such other calcium bearing rocks. Calcium contributes to the total hardness of water and is an important micro-nutrient in aquatic environment needed in large quantities by molluscs and vertebrates. It is measured by EDTA titrimetric method and the results of the analysis is reported in mg CaCO3/L. Small concentration of calcium carbonate prevents corrosion of metal pipes by laying down a protective coating (http://ces.iisc.ernet.in/energy/monograph1/Methpage1.html). Calcium salts can also be readily precipitated from water and high levels of calcium hardness tend to promote scale formation in the water system (http://www.aquaticlife.ca/Parameters/CalciumHardness.asp).

There is no set DENR Class C criterion for calcium hardness. The highest among the annual mean calcium hardness levels in the lake was 64 mg CaCO3/L in 2010 at Stn. V (Northern West Bay) while the lowest was 31 mg CaCO3/L in 2011 and 2012 in Stn. II (East Bay). It was also noted that the year when all of the monitored lake stations obtained their highest annual mean calcium hardness concentrations during the four- year monitoring period was in 2010.

In the tributary rivers, the annual average calcium hardness was highest in Pililla River in 2012 at 142 mg CaCO3/L and lowest at 18 mg CaCO3/L was in Pagsanjan River in 2010.

LAGUNA DE BAY Chemical Oxygen Demand, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 6 41 33 21 Stn. II (East Bay) 22 18 19 18 Stn. IV (Central Bay) 3 25 22 16 Stn. V (Northern West Bay) 4 25 22 18 Stn. VIII (South Bay) 5 21 23 17 Stn. XV San Pedro (West Bay) * * * 18 Stn. XVI Sta Rosa (West Bay) * * * 16 Stn. XVII Fish Sanctuary (Central Bay) * * * 18 Stn. XVIII Pagsanjan (East Bay) * * * 21

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for COD - none

B. Graphs

LAGUNA DE BAY Chemical Oxygen Demand (COD)

40 35

mg/L 20

10 5 0 2009 2010 2011 2012

Stn. I (Central West Bay) Stn. II (East Bay)Years Stn. IV (Central Bay) Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay)

Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay)

TRIBUTARY RIVERS Chemical Oxygen Demand, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 29 35 31 32 2 Bagumbayan River (Taguig) 138 332 169 134 3 Buli Creek (Taguig) 125 361 248 225 Mangangate River 4 (Muntinlupa) -Downstream 84 158 70 75 Mangangate River 4U (Muntinlupa) -Upstream * * * 71 Tunasan River (Muntinlupa) 5 -Downstream 572 227 244 249 Tunasan River (Muntinlupa) 5U -Upstream * * * 40 6 San Pedro River (T2) 75 61 142 62 7 Biñan River * * 42 87 Sta. Rosa River - 8 Downstream * * 44 38 Notes: 8M Sta. Rosa River - Midstream * * * 52 8U Sta. Rosa River - Upstream * * * 45 Sampling Frequency - Once a month 9 Cabuyao River 55 23 46 40 DENR Class C criterion for COD - 10 San Cristobal River (T3) 79 195 133 66 none 11 San Juan River (T5) 51 25 21 29 12 Molawin Creek (Los Baños) * * 16 25 * No sampling done 13 Bay River (T9) 38 21 21 21 14 Pila River * * 15 30 15 Sta. Cruz River (T6) 28 33 9 30 16 Pagsanjan River (T8) 36 97 15 19 17 Pangil River - Downstream 15 17 8 26 17U Pangil River - Upstream * * * 12 18 Siniloan River 30 22 17 21 Sta. Maria River - 19 Downstream * * 16 17 19U Sta. Maria River - Upstream * * * 8 20 Jala-jala River * * * 9 21 Pililla River * * 12 16 22 Tanay River - Downstream 43 28 14 13 22U Tanay River - Upstream * * * 7 23 Baras River * * 24 17 24 Morong River - Downstream 16 38 35 33 24U Morong River - Upstream * * * 50 Manggahan Floodway 25 (Taytay) 22 73 36 34 26 Sapang Baho River (Cainta) 34 37 44 46

B. Graphs:

TRIBUTARY RIVERS Chemical Oxygen Demand 700

600

500

400

mg/L 300

200

100

CHEMICAL OXYGEN DEMAND

The COD is the amount of oxygen which is needed for the oxidation of all organic substances in water in mg/L or g/m3. It is measured by Dichromate Reflux Method. The intrinsic limitation of the test lies in its ability to differentiate between the biologically oxidizable and inert material (http://ces.iisc.ernet.in/energy/monograph1/Methpage1. html). The main use of COD as an indicator of the organic and inorganic matter within water and effluent discharge is it provides information on the quantity of oxygen required to completely oxidize both the organic and inorganic material present in water. There are other tests that are also used to measure the organic content of a water body, such as the biological oxygen demand test. One advantage of the COD test over other tests, such as the BOD test is that it is relatively fast to carry out, for example the BOD test takes place over a five-day incubation period while the COD tests can be carried out in 2 hours; hence provides a much quicker indication of water quality. This property of the test has resulted in a wide range of usage when monitoring and controlling the organic content of industrial waste from effluent systems and the receiving water bodies (http://www.writework.com/essay/determination-chemical-oxygen-demand- cod- river- water-samples).

From 2009 to 2012, the annual average COD levels in the lake ranged from 4 mg/L (in 2009 at Stn. V – Northern West Bay) to 41 mg/L (in 2010 at Stn. I – Central West Bay). The range of annual mean COD concentrations in the tributaries were comparatively higher than in the lake at 7 mg/L in 2011 in Stn. 22U (Tanay River Upstream) and 572 mg/L in 2009 in Stn. 5 (Tunasan River Downstream).

LAGUNA DE BAY Chloride, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 45 342 146 60 Stn. II (East Bay) 36 102 123 41 Stn. IV (Central Bay) 46 220 155 52 Stn. V (Northern West Bay) 44 459 134 48 Stn. VIII (South Bay) 35 99 117 42 Stn. XV San Pedro (West Bay) * * * 52 Stn. XVI Sta Rosa (West Bay) * * * 51 Stn. XVII Fish Sanctuary (Central Bay) * * * 50 Stn. XVIII Pagsanjan (East Bay) * * * 38

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Chloride - 350 mg/L

B. Graphs

LAGUNA DE BAY Chloride

500 450 400 350 300 250

200 mg/L 150 100 50 0 2009 2010 2011 2012 Stn. I (Central West Bay) Stn. II (East Bay) Stn. IV (Central Bay) Years Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay) DENR Class C Criterion

TRIBUTARY RIVERS Chloride, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 29 35 31 32 2 Bagumbayan River (Taguig) 104 148 117 96 3 Buli Creek (Taguig) 87 115 115 75 Mangangate River 4 (Muntinlupa) -Downstream 71 116 117 70 Mangangate River 4U (Muntinlupa) -Upstream * * * 58 Tunasan River (Muntinlupa) 5 -Downstream 71 116 117 70 Tunasan River (Muntinlupa) 5U -Upstream * * * 62 6 San Pedro River (T2) 53 76 71 56 7 Biñan River * * 69 77 Sta. Rosa River - 8 Downstream * * 100 77 Notes: 8M Sta. Rosa River - Midstream * * * 76 8U Sta. Rosa River - Upstream * * * 36 Sampling Frequency - Once a month 9 Cabuyao River 47 56 76 56 DENR Class C criterion for 10 San Cristobal River (T3) 99 118 122 83 Chloride -350 mg/L 11 San Juan River (T5) 39 60 69 57 12 Molawin Creek (Los Baños) * * 42 42 * No sampling done 13 Bay River (T9) 18 26 21 26 14 Pila River * * 15 22 15 Sta. Cruz River (T6) 12 19 16 18 16 Pagsanjan River (T8) 11 17 17 18 17 Pangil River - Downstream 16 14 12 19 17U Pangil River - Upstream * * * 18 18 Siniloan River 13 19 15 24 Sta. Maria River - 19 Downstream * * 15 19 19U Sta. Maria River - Upstream * * * 19 20 Jala-jala River * * * 20 21 Pililla River * * 20 21 22 Tanay River - Downstream 14 18 14 21 22U Tanay River - Upstream * * * 23 23 Baras River * * 34 22 24 Morong River - Downstream 25 36 28 34 24U Morong River - Upstream * * * 34 Manggahan Floodway 25 (Taytay) 34 39 33 35 26 Sapang Baho River (Cainta) 37 46 38 33

B. Graphs:

TRIBUTARY RIVERS Chloride 400

350

300

250

200 mg/L

150

100

CHLORIDE

Chloride, in the form of the Cl– ion, is one of the major inorganic anions, or negative ions, in saltwater and freshwater. It originates from the dissociation of salts, such as sodium chloride or calcium chloride, in water. These salts, and their resulting chloride ions, originate from natural minerals, saltwater intrusion and industrial pollution.

The possible sources of manmade salts that may contribute to elevated chloride concentrations are chlorinated drinking water and sodium-chloride water softeners which often increase chloride levels in wastewater.

In drinking water, the salty taste produced by chloride depends upon the concentration of the chloride ion. Water containing 250 mg/L of chloride may have a detectable salty taste if the chloride came from sodium chloride. The recommended maximum level of chloride in U.S. drinking water is 250 mg/L (http://www.vernier.com/experiments/ wqv/15/chloride_ and_salinity/).

In Laguna de Bay, the intrusion of seawater from Manila Bay via the Pasig River during seawater backflow whenever the lake level drops to elevation 10.5 meters, has been always responsible for the increase in the chloride concentration of the water.

Except in Stn. V (Northern West Bay) in 2010, all of the average chloride concentrations in the lake from 2009 to 2012 were within the DENR Class C criterion of 350 mg/L. Stn. V yielded the highest average chloride level in 2010 at 459 mg/L due to the very high chloride concentration recorded in June in this station at 3,534 mg/L, an indication that there was an intrusion of seawater into the lake from the Pasig River backflow. There were no seawater backflow noted in the lake in 2009, 2011 and 2012 as all of the measured monthly chloride concentrations in Stn. V never exceeded the 350 mg/L Class C criterion.

All of the computed average chloride concentrations in the tributary rivers from 2009 to 2013 were within the Class C criterion for chloride.

LAGUNA DE BAY Dissolved Oxygen, mg/L

C. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 7.8 9.1 7.7 7.6 Stn. II (East Bay) 9.0 8.0 8.2 7.9 Stn. IV (Central Bay) 8.1 8.8 8.5 8.0 Stn. V (Northern West Bay) 8.0 8.6 7.4 7.5 Stn. VIII (South Bay) 8.4 8.0 8.1 8.1 Stn. XV San Pedro (West Bay) * * * 8.2 Stn. XVI Sta Rosa (West Bay) * * * 8.1 Stn. XVII Fish Sanctuary (Central Bay) * * * 7.9 Stn. XVIII Pagsanjan (East Bay) * * * 8.0

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for DO - 5.0 mg/L

B. Graphs

LAGUNA DE BAY Dissolved Oxygen (DO)

10.0 9.0 8.0 7.0 6.0

5.0 mg/L 4.0 3.0 2.0 1.0 0.0 2009 2010 Years 2011 2012 Stn. I (Central West Bay) Stn. II (East Bay) Stn. IV (Central Bay) Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay) DENR Class C Criterion

TRIBUTARY RIVERS Dissolved Oxygen, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 2.9 2.1 1.9 1.9 2 Bagumbayan River (Taguig) 2.5 0.1 0.5 0.3 3 Buli Creek (Taguig) 1.7 0.1 0.1 0.2 Mangangate River 4 (Muntinlupa) -Downstream 1.8 0.1 0.2 1.3 Mangangate River 4U (Muntinlupa) -Upstream * * * 3.6 Tunasan River (Muntinlupa) 5 -Downstream 0.9 0.1 0.2 0.1 5U Tunasan River (Muntinlupa) -Upstream * * * 4.1 6 San Pedro River (T2) 2.7 0.2 1.3 1.2 7 Biñan River * * 0.6 0.6 Sta. Rosa River - 8 Downstream * * 1.1 2.2 Notes: 8M Sta. Rosa River - Midstream * * * 2.0 8U Sta. Rosa River - Upstream * * * 5.8 Sampling Frequency - Once a month 9 Cabuyao River 3.5 0.6 0.7 0.8 DENR Class C criterion for DO - 10 San Cristobal River (T3) 4.3 1.3 1.2 2.0 5.0 mg/L 11 San Juan River (T5) 4.5 3.6 2.8 3.0 12 Molawin Creek (Los Baños) * * 4.4 3.3 * No sampling done 13 Bay River (T9) 7.3 7.0 6.6 6.8 14 Pila River * * 5.1 4.8 15 Sta. Cruz River (T6) 6.7 7.0 6.5 6.5 16 Pagsanjan River (T8) 7.2 7.0 7.3 6.4 17 Pangil River - Downstream 8.2 7.1 7.3 7.3 17U Pangil River - Upstream * * * 7.4 18 Siniloan River 3.4 5.4 4.6 2.7 Sta. Maria River - 19 Downstream * * 6.5 6.5 19U Sta. Maria River - Upstream * * * 8.4 20 Jala-jala River * * * 6.0 21 Pililla River * * 3.9 3.7 22 Tanay River - Downstream 5.9 5.1 5.5 6.5 22U Tanay River - Upstream * * * 7.8 23 Baras River * * 3.9 4.7 24 Morong River - Downstream 8.8 5.0 7.3 4.9 24U Morong River - Upstream * * * 6.4 Manggahan Floodway 25 (Taytay) 4.4 1.9 1.7 2.3 26 Sapang Baho River (Cainta) 2.3 1.0 0.8 1.8

B. Graphs:

TRIBUTARY RIVERS Dissolved Oxygen 10.0

9.0

8.0

7.0

6.0

5.0 mg/L 4.0

3.0

2.0

1.0

0.0 2009 2010 2011 2012 Year 1 Marikina River 2 Bagumbayan River (Taguig) 3 Buli Creek (Taguig) 4 Mangangate River (Muntinlupa) -Downstream 4U Mangangate River (Muntinlupa) -Upstream 5 Tunasan River (Muntinlupa) -Downstream 5U Tunasan River (Muntinlupa) -Upstream 6 San Pedro River (T2) 7 Biñan River 8 Sta. Rosa River - Downstream 8M Sta. Rosa River - Midstream 8U Sta. Rosa River - Upstream 9 Cabuyao River 10 San Cristobal River (T3) 11 San Juan River (T5) 12 Molawin Creek (Los Baños) 13 Bay River (T9) 14 Pila River 15 Sta. Cruz River (T6) 16 Pagsanjan River (T8) 17 Pangil River - Downstream 17U Pangil River - Upstream 18 Siniloan River 19 Sta. Maria River - Downstream 19U Sta. Maria River - Upstream 20 Jala-jala River 21 Pililla River 22 Tanay River - Downstream 22U Tanay River - Upstream 23 Baras River 24 Morong River - Downstream 24U Morong River - Upstream 25 Manggahan Floodway (Taytay) 26 Sapang Baho River (Cainta) DENR Class C Criterion

DISSOLVED OXYGEN

Aquatic organisms require oxygen in the free elemental state as a dissolved gas. The amount of dissolved oxygen (DO) in the water is fundamental to the survival of most aquatic organisms. Lack of significant levels of dissolved oxygen required by most aquatic organisms for respiration can cause impairment or death.

The two main sources of dissolved oxygen are diffusion of oxygen from the air and photosynthetic activity. Oxygen is soluble in water and the oxygen that is dissolved in water will equilibrate with the oxygen in atmosphere. Oxygen tends to be less soluble as temperature increases. Diffusion of oxygen from the air into water depends on the solubility of oxygen, and is influenced by many other factors like water movement, temperature, salinity, etc. Photosynthesis of aquatic plants will increase the DO during day light hours and the DO levels will fall during the nighttime hours (http://ces.iisc.ernet.in/energy/ monograph1/Methpage1.html).

In natural waters, man-made contamination, or natural organic material will be consumed by microorganisms. As this microbial activity increases due to high organic loadings, oxygen will be consumed out of the water by the organisms to facilitate their digestion process. Typically, DO levels of less than 2 mg/l will kill the fish (http://www.stevenswater.com/articles/waterparameters.aspx).

The lake‘s average annual DO levels in all monitored stations from 2009 to 2012 conformed to the DENR Class C criterion set at a minimum of 5 mg/L.

Only 11 of the 34 tributary river stations monitored in 2009 to 2012 had all of the computed average annual DO concentrations passed the Class C criterion and these are Bay River (Stn. 13), Sta. Cruz River (Stn. 15), Pagsanjan River (Stn. 16), Pangil River Downstream (Stn. 17), Pangil River Upstream (Stn. 17U), Sta. Maria River Downstream (Stn 19), Sta. Maria River Upstream (Stn 19U), Jala-jala River (Stn. 20), Tanay River-Downstream (Stn. 22), Tanay River-Upstream (Stn 22U) and Morong River-Upstream (Stn. 24U). Those tributary river stations whose annual mean concentrations for DO always failed the Class C criterion were Stns. 1 to 12, 21, 23, 25 and 26. For Stns. 14, 18 and 24, measured annual average DO concentrations occasionally passed the Class C criterion.

LAGUNA DE BAY Inorganic Phosphate, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 0.084 0.108 0.102 0.112 Stn. II (East Bay) 0.084 0.085 0.035 0.128 Stn. IV (Central Bay) 0.089 0.088 0.045 0.110 Stn. V (Northern West Bay) 0.091 0.190 0.061 0.139 Stn. VIII (South Bay) 0.095 0.105 0.075 0.111 Stn. XV San Pedro (West Bay) * * * 0.110 Stn. XVI Sta Rosa (West Bay) * * * 0.101 Stn. XVII Fish Sanctuary (Central Bay) * * * 0.098 Stn. XVIII Pagsanjan (East Bay) * * * 0.055

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Inorganic Phosphate – 0.05 mg/L

B. Graphs

TRIBUTARY RIVERS Inorganic Phosphate, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 0.60 1.77 0.48 0.42 2 Bagumbayan River (Taguig) 2.25 8.32 1.48 1.37 3 Buli Creek (Taguig) 2.19 7.95 1.83 1.63 Mangangate River 4 (Muntinlupa) -Downstream 1.55 6.36 1.35 0.77 Mangangate River 4U (Muntinlupa) -Upstream * * * 0.78 Tunasan River (Muntinlupa) 5 -Downstream 4.56 17.43 2.35 2.15 Tunasan River (Muntinlupa) 5U -Upstream * * * 0.87 6 San Pedro River (T2) 2.91 8.56 1.93 1.55 7 Biñan River * * 0.96 1.19 Sta. Rosa River - 8 Downstream * * 1.43 0.90 Notes: 8M Sta. Rosa River - Midstream * * * 0.74 8U Sta. Rosa River - Upstream * * * 0.57 Sampling Frequency - Once a month 9 Cabuyao River 1.56 3.78 1.02 1.05 DENR Class C criterion for 10 San Cristobal River (T3) 0.82 1.58 0.46 0.50 Inorganic Phosphate – 0.4 mg/L 11 San Juan River (T5) 1.21 2.19 0.75 0.58 12 Molawin Creek (Los Baños) * * 0.36 0.29 * No sampling done 13 Bay River (T9) 0.60 0.87 0.32 0.31 14 Pila River * * 0.14 0.21 15 Sta. Cruz River (T6) 0.54 1.00 0.32 0.33 16 Pagsanjan River (T8) 0.10 0.23 0.09 0.06 17 Pangil River - Downstream 0.10 0.26 0.07 0.08 17U Pangil River - Upstream * * * 0.06 18 Siniloan River 0.27 0.63 0.09 0.09 Sta. Maria River - 19 Downstream * * 0.07 0.07 19U Sta. Maria River - Upstream * * * 0.06 20 Jala-jala River * * * 0.32 21 Pililla River * * 0.32 0.30 22 Tanay River - Downstream 0.51 0.66 0.30 0.21 22U Tanay River - Upstream * * * 0.10 23 Baras River * * 0.36 0.24 24 Morong River - Downstream 2.33 4.43 1.17 1.25 24U Morong River - Upstream * * * 1.24 Manggahan Floodway 25 (Taytay) 0.55 2.14 0.71 0.58 26 Sapang Baho River (Cainta) 0.80 3.56 0.93 0.75

B. Graphs:

TRIBUTARY RIVERS Inorganic Phosphate 19.00 18.00 17.00 16.00 15.00 14.00 13.00 12.00 11.00 10.00

9.00 mg/L 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 2009 2010 2011 2012

1 Marikina River 2 Bagumbayan River (Taguig) 3 Buli Creek (Taguig) 4 Mangangate River (Muntinlupa) -Downstream 4U Mangangate River (Muntinlupa) -Upstream Year 5 Tunasan River (Muntinlupa) -Downstream 5U Tunasan River (Muntinlupa) -Upstream 6 San Pedro River (T2) 7 Biñan River 8 Sta. Rosa River - Downstream 8M Sta. Rosa River - Midstream 8U Sta. Rosa River - Upstream 9 Cabuyao River 10 San Cristobal River (T3) 11 San Juan River (T5) 12 Molawin Creek (Los Baños) 13 Bay River (T9) 14 Pila River 15 Sta. Cruz River (T6) 16 Pagsanjan River (T8) 17 Pangil River - Downstream 17U Pangil River - Upstream 18 Siniloan River 19 Sta. Maria River - Downstream 19U Sta. Maria River - Upstream 20 Jala-jala River 21 Pililla River 22 Tanay River - Downstream 22U Tanay River - Upstream 23 Baras River 24 Morong River - Downstream 24U Morong River - Upstream 25 Manggahan Floodway (Taytay) 26 Sapang Baho River (Cainta) DENR Class C Criterion (0.05 mg/L)

INORGANIC PHOSPHATE

Phosphorus is an essential nutrient for aquatic life. It occurs naturally in the environment in small amounts. Phosphorus is often the "growth-limiting" factor for plants as high levels can lead to algal blooms and excessive nutrients in the water.

Phosphorus occurs in several forms—both inorganic and organic. Inorganic 3- orthophosphate (PO4 ) is the only form available to living organisms. However, the other forms of phosphate can be transformed into orthophosphate. For this reason, total phosphate is generally measured in addition to orthophosphate. The measure of total phosphate provides an estimate of the amount of phosphorus potentially available to plants and animals.

Common sources of phosphorus include agricultural runoff, animal waste and sewage that contain organic phosphorus as well as inorganic phosphorus in products such as detergents (http://www.cotf.edu/ete/modules/waterq3/WQassess3e.html).

The DENR‘s Class C Water Quality Criterion for inorganic phosphate is at 0.05 mg/L for the lake and 0.4 mg/L for the tributary rivers.

The results of the monitoring in the lake from 2009 to 2012 showed that except for Stn. II (East Bay) and Stn. IV (Central Bay) in 2011, all of the computed annual average inorganic phosphate concentrations failed the Class C criterion.

Among the 34 tributary river stations monitored from 2009 to 2012, all of the annual average inorganic phosphate concentrations in Stns. 1, 2, 3, 4, 4U, 5, 5U, 6, 7, 8, 8M, 8U, 9, 10, 11, 24, 24U, 25 and 26 exceeded the Class C criterion of 0.4 mg/L. On the other hand, those river stations whose annual average inorganic phosphate concentrations all conformed with the Class C criterion were Stns. 12, 14, 16, 17, 17U, 19, 19U, 20, 21, 22U and 23.

LAGUNA DE BAY Nitrate, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 0.224 0.224 0.184 0.181 Stn. II (East Bay) 0.210 0.206 0.098 0.121 Stn. IV (Central Bay) 0.165 0.142 0.204 0.165 Stn. V (Northern West Bay) 0.407 0.320 0.174 0.159 Stn. VIII (South Bay) 0.292 0.181 0.107 0.147 Stn. XV San Pedro (West Bay) * * * 0.116 Stn. XVI Sta Rosa (West Bay) * * * 0.120 Stn. XVII Fish Sanctuary (Central Bay) * * * 0.117 Stn. XVIII Pagsanjan (East Bay) * * * 0.038

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Nitrate – 10 mg/L

B. Graphs

LAGUNA DE BAY Nitrate

1.000 0.900 0.800 DENR Class C criterion = 10 mg/L 0.700 0.600

0.500 mg/L 0.400 0.300 0.200 0.100 0.000 2009 2010 2011 2012

TRIBUTARY RIVERS Nitrate, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 0.7 0.5 0.5 0.3 2 Bagumbayan River (Taguig) 0.3 0.2 0.1 0.1 3 Buli Creek (Taguig) 0.1 0.3 0.1 0.1 Mangangate River 4 (Muntinlupa) -Downstream 0.1 0.2 0.1 0.1 Mangangate River 4U (Muntinlupa) -Upstream * * * 0.3 Tunasan River (Muntinlupa) 5 -Downstream 0.1 0.4 0.2 0.2 Tunasan River (Muntinlupa) 5U -Upstream * * * 2.2 6 San Pedro River (T2) 0.4 0.2 0.4 0.7 7 Biñan River * * 0.3 0.3 Sta. Rosa River - 8 Downstream * * 0.2 0.3 Notes: 8M Sta. Rosa River - Midstream * * * 0.6 8U Sta. Rosa River - Upstream * * * 1.5 Sampling Frequency - Once a month 9 Cabuyao River 0.4 0.3 0.1 0.1 DENR Class C criterion for Nitrate 10 San Cristobal River (T3) 0.8 0.1 0.2 0.2 – 10 mg/L 11 San Juan River (T5) 5.3 6.8 3.6 5.9 12 Molawin Creek (Los Baños) * * 0.7 0.5 * No sampling done 13 Bay River (T9) 1.5 0.9 0.6 0.7 14 Pila River * * 0.4 0.4 15 Sta. Cruz River (T6) 0.9 0.6 0.6 0.9 16 Pagsanjan River (T8) 0.8 0.4 0.3 0.3 17 Pangil River - Downstream 0.2 0.4 0.1 0.1 17U Pangil River - Upstream * * * 0.1 18 Siniloan River 0.3 0.6 0.3 0.3 Sta. Maria River - 19 Downstream * * 0.3 0.3 19U Sta. Maria River - Upstream * * * 0.2 20 Jala-jala River * * * 0.5 21 Pililla River * * 0.6 0.5 22 Tanay River - Downstream 1.0 1.2 0.9 1.0 22U Tanay River - Upstream * * * 0.6 23 Baras River * * 0.9 0.7 24 Morong River - Downstream 3.1 1.8 1.4 1.9 24U Morong River - Upstream * * * 1.1 Manggahan Floodway 25 (Taytay) 0.6 0.4 0.4 0.2 26 Sapang Baho River (Cainta) 1.0 0.6 0.8 0.4

B. Graphs:

TRIBUTARY RIVERS Nitrate 10.0

9.0

8.0

7.0

6.0

5.0 mg/L 4.0

3.0

2.0

1.0

NITRATE

Nitrates are the most oxidized forms of nitrogen and the end product of the aerobic decomposition of organic nitrogenous matter. It commonly occurs in small amounts in surface waters. Nitrates are essential plant nutrients, but in excess amounts they can cause significant water quality problems. Together with phosphorus, excessive nitrate concentration can accelerate eutrophication, causing dramatic increases in aquatic plant growth and changes in the types of plants and animals that live in a water body. This, in turn, affects dissolved oxygen, temperature, and other indicators. Excess nitrates can cause hypoxia (low levels of dissolved oxygen) and can become toxic to warm-blooded animals at higher concentrations (10 mg/L) or higher) under certain conditions (http://water.epa.gov/type/rsl/monitoring/vms57.cfm).

Sources of nitrates include chemical fertilizers from cultivated lands, drainage from livestock feeds, as well as domestic and industrial discharges (http://ces.iisc.ernet. in/energy/monograph1/Methpage1.html).

The average annual nitrate concentrations in all monitored stations in the lake and in the tributary rivers from 2009 to 2012 were way below the 10 mg/L DENR water quality criterion for Class C. The annual mean nitrate levels in the lake ranged from 0.038 to 0.407 mg/L while in the tributary rivers ranged from 0.1 to 6.8 mg/L. Among the 34 tributary river stations, Stn. 11 (San Juan River) always had the highest annual mean nitrate concentration every year from 2009 to 2012.

LAGUNA DE BAY Oil and Grease, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 1 1 2 1 Stn. II (East Bay) 1 2 2 1 Stn. IV (Central Bay) 1 1 1 2 Stn. V (Northern West Bay) 2 2 2 1 Stn. VIII (South Bay) 1 1 2 1 Stn. XV San Pedro (West Bay) * * * 1 Stn. XVI Sta Rosa (West Bay) * * * 2 Stn. XVII Fish Sanctuary (Central Bay) * * * 2 Stn. XVIII Pagsanjan (East Bay) * * * 1

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Oil and Grease – 2.0 mg/L

B. Graphs

LAGUNA DE BAY Oil and Grease

2.4 2.2 2.0 1.8 1.6 1.4 1.2

1.0 mg/L 0.8 0.6 0.4 0.2 0.0 2009 2010 2011 2012

TRIBUTARY RIVERS Oil and Grease, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 1 3 2 1 2 Bagumbayan River (Taguig) 1 4 3 2 3 Buli Creek (Taguig) 3 4 4 2 Mangangate River 4 (Muntinlupa) -Downstream 3 3 2 1 Mangangate River 4U (Muntinlupa) -Upstream * * * 1 Tunasan River (Muntinlupa) 5 -Downstream 10 5 7 4 Tunasan River (Muntinlupa) 5U -Upstream * * * 1 6 San Pedro River (T2) 1 3 4 1 7 Biñan River * * 2 1 Sta. Rosa River - 8 Downstream * * 2 1 Notes: 8M Sta. Rosa River - Midstream * * * 3 8U Sta. Rosa River - Upstream * * * 2 Sampling Frequency - Once a month 9 Cabuyao River 2 2 2 1 DENR Class C criterion for Oil and 10 San Cristobal River (T3) 2 2 2 2 Grease – 2.0 mg/L 11 San Juan River (T5) 1 2 2 2 12 Molawin Creek (Los Baños) * * 2 1 * No sampling done 13 Bay River (T9) 1 1 1 1 14 Pila River * * 2 2 15 Sta. Cruz River (T6) 1 1 2 2 16 Pagsanjan River (T8) 1 1 2 2 17 Pangil River - Downstream 1 1 2 2 17U Pangil River - Upstream * * * 1 18 Siniloan River 1 1 2 1 Sta. Maria River - 19 Downstream * * 2 1 19U Sta. Maria River - Upstream * * * 1 20 Jala-jala River * * * 2 21 Pililla River * * 2 1 22 Tanay River - Downstream 1 2 2 1 22U Tanay River - Upstream * * * 1 23 Baras River * * 2 2 24 Morong River - Downstream 2 2 2 1 24U Morong River - Upstream * * * 1 Manggahan Floodway 25 (Taytay) 1 2 2 1 26 Sapang Baho River (Cainta) 1 2 3 1

B. Graphs: TRIBUTARY RIVERS Oil and Grease 11

mg/L 5

OIL AND GREASE

Oil and grease (O&G) is a measure of a variety of substances including fuels, motor oil, lubricating oil, hydraulic oil, cooking oil, and animal-derived fats. The concentration of these substances is typically measured within a body of water. Lakes, river, storm water runoff, and wastewater are all monitored for oil and grease. Sources of oil and grease are mainly anthropogenic. Oil and greases should be contained and/or recycled typically to keep them from entering the environment.

Toxicity varies among different types of oils and greases. Refined oils are generally more toxic than crude oils. Various hydrocarbons found in fuels can pose a wide range of human health problems, from affecting the liver, kidneys and blood to increasing the risk of cancer (http://www.stormwaterx.com/Resources/IndustrialPollutants/OilGrease. aspx).

In a body of water such as lakes and rivers, free oil and emulsions may act on the epithelial surfaces of fish gills and interfere with respiration. They may coat and destroy algae and other plankton, thereby removing a source of fish food, and when ingested by fish they may taint their flesh. Settleable oily substances may also coat the bottom, destroy benthic organisms, and interfere with spawning areas. Oil may be absorbed quickly by suspended matter, such as clay, and then due to wind and strong currents may be transported over wide areas and deposited on the bottom far from the source. Even when deposited on the bottom, oil continuously yields water soluble substances that are toxic to aquatic life. In addition, films of oil on the surface may interfere with reaeration and photosynthesis, thus, preventing the respiration of aquatic insects such as water boatman, backswimmers and some species of aquatic flies. Moreover, oil is detrimental to waterfowl by destroying the natural buoyancy and insulation of their feathers (U.S. Federal Water Pollution Control Administration, 1968).

From 2009 to 2012, all of the annual average oil and grease concentrations in the lake complied with the 2.0 mg/L DENR Class C criterion.

The 2009 to 2012 annual average concentrations of oil and grease in the tributary rivers revealed that those stations that failed the Class C criterion were Stn. 1 (Marikina River) in 2010, Stn. 2 (Bagumbayan River) in 2010 and 2011, Stn. 3 (Buli Creek) from 2009 to 2011, Stn. 4 (Mangangate River-Downstream) in 2009 to 2010, Stn. 5 (Tunasan River – Downstream in 2009 to 2012, Stn. 6 (San Pedro River) in 2010 and 2011, Stn. 8M (Sta. Rosa Midstream) in 2012, and Stn. 26 (Sapang Baho River) in 2011.

LAGUNA DE BAY pH, units

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 8.3 8.0 7.7 8.5 Stn. II (East Bay) 8.3 8.2 7.8 8.6 Stn. IV (Central Bay) 8.2 8.4 8.0 8.6 Stn. V (Northern West Bay) 8.3 8.2 7.8 8.4 Stn. VIII (South Bay) 8.3 8.1 7.9 8.3 Stn. XV San Pedro (West Bay) * * * 8.7 Stn. XVI Sta Rosa (West Bay) * * * 8.6 Stn. XVII Fish Sanctuary (Central Bay) * * * 8.7 Stn. XVIII Pagsanjan (East Bay) * * * 8.7

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for pH – 6.5 to 8.5

B. Graphs

TRIBUTARY RIVERS pH, units

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 7.3 7.1 7.1 7.5 2 Bagumbayan River (Taguig) 7.5 7.3 7.1 7.5 3 Buli Creek (Taguig) 7.5 7.5 7.2 7.4 Mangangate River 4 (Muntinlupa) -Downstream 7.5 7.4 7.3 7.4 Mangangate River 4U (Muntinlupa) -Upstream * * * 7.7 Tunasan River (Muntinlupa) 5 -Downstream 7.2 7.2 7.0 7.3 Tunasan River (Muntinlupa) 5U -Upstream * * * 7.9 6 San Pedro River (T2) 7.5 7.5 7.4 7.7 7 Biñan River * * 7.3 7.7 Sta. Rosa River - 8 Downstream * * 7.4 7.6 Notes: 8M Sta. Rosa River - Midstream * * * 7.7 8U Sta. Rosa River - Upstream * * * 7.9 Sampling Frequency - Once a month 9 Cabuyao River 7.5 7.4 7.3 7.6 DENR Class C criterion for pH – 6.5 to San Cristobal River (T3) 10 7.4 7.0 7.0 7.4 8.5 11 San Juan River (T5) 7.2 7.1 7.0 7.4 12 Molawin Creek (Los Baños) * * 7.2 7.5 * No sampling done 13 Bay River (T9) 7.9 7.7 7.7 8.1 14 Pila River * * 7.2 7.5 15 Sta. Cruz River (T6) 7.5 7.4 7.3 7.6 16 Pagsanjan River (T8) 7.3 7.4 7.1 7.4 17 Pangil River - Downstream 7.4 7.3 6.9 7.6 17U Pangil River - Upstream * * * 7.4 18 Siniloan River 6.8 7.0 6.8 7.1 Sta. Maria River - 19 Downstream * * 7.1 7.8 19U Sta. Maria River - Upstream * * * 8.5 20 Jala-jala River * * * 7.5 21 Pililla River * * 7.0 7.5 22 Tanay River - Downstream 7.6 7.5 7.6 8.1 22U Tanay River - Upstream * * * 8.6 23 Baras River * * 6.9 7.4 24 Morong River - Downstream 7.9 7.5 7.7 8.1 24U Morong River - Upstream * * * 8.0 Manggahan Floodway 25 (Taytay) 7.4 7.3 7.2 7.5 26 Sapang Baho River (Cainta) 7.3 7.0 7.1 7.4

B. Graphs:

TRIBUTARY RIVERS pH 10.0

9.0

8.0

7.0

6.0

5.0 mg/L 4.0

3.0

2.0

1.0

0.0 2009 2010 2011 2012

1 Marikina River 2 Bagumbayan River (Taguig) 3 Buli Creek (Taguig) Year 4 Mangangate River (Muntinlupa) -Downstream 4U Mangangate River (Muntinlupa) -Upstream 5 Tunasan River (Muntinlupa) -Downstream 5U Tunasan River (Muntinlupa) -Upstream 6 San Pedro River (T2) 7 Biñan River 8 Sta. Rosa River - Downstream 8M Sta. Rosa River - Midstream 8U Sta. Rosa River - Upstream 9 Cabuyao River 10 San Cristobal River (T3) 11 San Juan River (T5) 12 Molawin Creek (Los Baños) 13 Bay River (T9) 14 Pila River 15 Sta. Cruz River (T6) 16 Pagsanjan River (T8) 17 Pangil River - Downstream 17U Pangil River - Upstream 18 Siniloan River 19 Sta. Maria River - Downstream 19U Sta. Maria River - Upstream 20 Jala-jala River 21 Pililla River 22 Tanay River - Downstream 22U Tanay River - Upstream 23 Baras River 24 Morong River - Downstream 24U Morong River - Upstream 25 Manggahan Floodway (Taytay) 26 Sapang Baho River (Cainta) DENR Class C Criterion (minimum) DENR Class C Criterion (maximum)

pH pH, as a measure of the hydrogen ion concentration, indicates whether the water is acidic or basic. The pH scale ranges from 0 to 14, with pH 7 being the neutral point. Thus, a water of pH 7 is neither acidic nor basic, while a water with pH below 7 is acidic and one with a pH above 7 is basic. pH is typically monitored for assessments of aquatic ecosystem, health, recreational waters, irrigation sources and discharges, livestock, drinking water sources, industrial discharges, intakes, and storm water runoff. (http:/www.stevenswater.com/articles/ waterparameters.aspx).

The effect of pH on the chemical and biological properties of liquids makes its determination very important. In natural waters, pH is governed by the equilibrium between carbon dioxide/bicarbonate/carbonate ions. It tends to increase during day largely due to the photosynthetic activity (consumption of carbon dioxide) and decreases during night due to respiratory activity. Wastewater and polluted natural waters may have pH values lower or higher than 7 depending on the nature of the pollutant. Low pH affects physiological and biological functions of aquatic life through the reduction of enzyme activity and effectiveness. Low pH results when atmospheric oxygen and water comes in contact with sulfides such as pyrite, which reacts and forms acid (http://ces.iisc.ernet.in/energy/monograph1/Methpage1.html).

The evaluation of the average annual pH levels in the lake from 2009 to 2012 showed that it was only in 2012 that the DENR Class C criterion of 6.5 to 8.5 was not met particularly in Stns. II (East Bay), IV (Central Bay) and XVI (West Bay-Sta Rosa) with pH 8.6; and in Stns. XV (West Bay- San Pedro), XVII (Central Bay-Fish Sanctuary) and XVIII (East Bay-Pagsanjan) with pH 8.7.

In the tributary rivers, only Stn. 22U (Tanay River Upstream) had annual average pH concentration that failed the DENR Class C criterion at 8.6 in 2012.

LAGUNA DE BAY Temperature, oC

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 27 29 28 29 Stn. II (East Bay) 27 29 28 29 Stn. IV (Central Bay) 27 29 29 28 Stn. V (Northern West Bay) 27 29 29 28 Stn. VIII (South Bay) 27 29 28 29 Stn. XV San Pedro (West Bay) * * * 29 Stn. XVI Sta Rosa (West Bay) * * * 29 Stn. XVII Fish Sanctuary (Central Bay) * * * 29 Stn. XVIII Pagsanjan (East Bay) * * * 29

Notes: * No data – not yet included in the LLDA‘s Water Quality Monitoring Program

Sampling Depth - Stn. I – composite of 0.5 and 2.0 m. Stn. XV – composite of 0.5 and 2.0 m. Stn. II – composite of 0.5 and 2.0 m. Stn. XVI – composite of 0.5 and 2.0 m. Stn. IV – 0.5 m. Stn. XVII – composite of 0.5 and 2.0 m. Stn. V – 0.5 m. Stn. XVIII – composite of 0.5 and 2.0 m. Stn. VIII – composite of 0.5 and 2.0 m.

Sampling Frequency – Once a month

DENR Class C criterion for Temperature – none (annual average)

B. Graphs

LAGUNA DE BAY Temperature

30 28 26 24 22 20 18 16

14 C

o 12 10 8 6 4 2 0

2009 2010 Years 2011 2012

Stn. I (Central West Bay) Stn. II (East Bay) Stn. IV (Central Bay) Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay)

TRIBUTARY RIVERS Temperature, oC

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 27 28 27 28 2 Bagumbayan River (Taguig) 28 28 28 29 3 Buli Creek (Taguig) 28 29 28 30 Mangangate River 4 (Muntinlupa) -Downstream 28 29 29 29 Mangangate River 4U (Muntinlupa) -Upstream * * * 28 Tunasan River (Muntinlupa) 5 -Downstream 32 33 32 31 Tunasan River (Muntinlupa) 5U -Upstream * * * 28 6 San Pedro River (T2) 28 29 28 29 7 Biñan River * * 29 28 Sta. Rosa River - 8 Downstream * * 30 29 Notes: 8M Sta. Rosa River - Midstream * * * 29 8U Sta. Rosa River - Upstream * * * 29 Sampling Frequency - Once a month 9 Cabuyao River 27 29 29 30 DENR Class C criterion for San Cristobal River (T3) 10 28 28 27 27 Temperature - none (annual average) 11 San Juan River (T5) 28 27 26 27 12 Molawin Creek (Los Baños) * * 28 29 * No sampling done 13 Bay River (T9) 28 28 27 29 14 Pila River * * 27 29 15 Sta. Cruz River (T6) 27 29 27 29 16 Pagsanjan River (T8) 27 28 27 29 17 Pangil River - Downstream 30 28 26 27 17U Pangil River - Upstream * * * 28 18 Siniloan River 28 29 32 26 Sta. Maria River - 19 Downstream * * 28 27 19U Sta. Maria River - Upstream * * * 27 20 Jala-jala River * * * 27 21 Pililla River * * 27 28 22 Tanay River - Downstream 29 28 26 30 22U Tanay River - Upstream * * * 29 23 Baras River * * 27 29 24 Morong River - Downstream 29 29 28 30 24U Morong River - Upstream * * * 29 Manggahan Floodway 25 (Taytay) 28 28 26 28 26 Sapang Baho River (Cainta) 28 28 28 28

B. Graphs:

TRIBUTARY RIVERS Temperature 35

20 mg/L 15

0 2009 2010 2011 2012

TEMPERATURE

Temperature is a measure of the warmness or coldness of the water body. It is an important parameter in water quality assessment because many aquatic organisms are sensitive to changes in water temperature. Water bodies will naturally show changes in temperature seasonally and daily. However, man made changes to water temperature will affect fish‘s ability to reproduce. Many lake and rivers will exhibit vertical temperature gradients as the sun will warm the upper water while deeper water will remain cooler (http://www.stevenswater.com/articles/waterparameters.aspx).

Solar radiation and atmospheric temperature brings about spatial and temporal changes in temperature, setting up convection currents and thermal stratification. As changes in temperature will have an effect on other water quality parameters such as alkalinity, salinity, dissolved oxygen, electrical conductivity, etc., the chemical and biological reactions are likewise affected such as solubility of oxygen, carbon-dioxide-carbonate- bicarbonate equilibrium, increase in metabolic rate and physiological reactions of organisms, etc. (http://ces.iisc.ernet.in/energy/monograph1/Methpage1.html)

In DAO 34, the Class C criterion for temperature is that the maximum rise should not be more than 3oC. Note that this criterions is not applied for the annual means.

The annual average temperature levels in the lake from 2009 to 2012 ranged from 27 oC to 29 oC. Apparently, the temperature of the lake was relatively colder in 2009 than in 2010 to 2012.

For tributary rivers, the annual average temperature was highest at 33 oC in Stn 5 (Tunasan River Downstream) in 2010 while the lowest at 26 oC was in Stn. 22 (Tanay River Downstream) in 2011. Throughout the 4-year monitoring period from 2009 to 2012, it appeared that Stn. 5 (Tunasan River Downstream) consistently registered the highest average annual temperature every year.

LAGUNA DE BAY Total Dissolved Solids, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 212 613 364 212 Stn. II (East Bay) 185 412 307 170 Stn. IV (Central Bay) 223 698 381 202 Stn. V (Northern West Bay) 208 421 348 204 Stn. VIII (South Bay) 195 395 315 221 Stn. XV San Pedro (West Bay) * * * 196 Stn. XVI Sta Rosa (West Bay) * * * 222 Stn. XVII Fish Sanctuary (Central Bay) * * * 347 Stn. XVIII Pagsanjan (East Bay) * * * 238

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Total Dissolved Solids - none

B. Graphs

LAGUNA DE BAY Total Dissolved Solids (TDS)

750 700 650 600 550 500 450 400 350

300 mg/L 250 200 150 100 50 0 2009 2010 2011 2012

TRIBUTARY RIVERS Total Dissolved Solids, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 483 182 323 315 2 Bagumbayan River (Taguig) 687 680 526 415 3 Buli Creek (Taguig) 615 664 602 458 Mangangate River 4 (Muntinlupa) -Downstream 504 577 491 343 Mangangate River 4U (Muntinlupa) -Upstream * * * 329 Tunasan River (Muntinlupa) 5 -Downstream 731 619 622 520 Tunasan River (Muntinlupa) 5U -Upstream * * * 421 6 San Pedro River (T2) 491 612 617 573 7 Biñan River * * 465 586 Sta. Rosa River - 8 Downstream * * 640 548 Notes: 8M Sta. Rosa River - Midstream * * * 541 8U Sta. Rosa River - Upstream * * * 314 Sampling Frequency - Once a month 9 Cabuyao River 487 457 542 501 DENR Class C criterion for Total 10 San Cristobal River (T3) 1093 690 2324 551 Dissolved Solids - none 11 San Juan River (T5) 422 499 562 510 12 Molawin Creek (Los Baños) * * 327 355 * No sampling done 13 Bay River (T9) 344 285 344 377 14 Pila River * * 205 257 15 Sta. Cruz River (T6) 178 209 196 215 16 Pagsanjan River (T8) 102 166 104 129 17 Pangil River - Downstream 97 84 99 141 17U Pangil River - Upstream * * * 121 18 Siniloan River 98 78 103 139 Sta. Maria River - 19 Downstream * * 155 223 19U Sta. Maria River - Upstream * * * 135 20 Jala-jala River * * * 483 21 Pililla River * * 244 232 22 Tanay River - Downstream 264 248 261 271 22U Tanay River - Upstream * * * 246 23 Baras River * * 247 208 24 Morong River - Downstream 400 304 395 420 24U Morong River - Upstream * * * 421 Manggahan Floodway 25 (Taytay) 266 215 246 286 26 Sapang Baho River (Cainta) 306 232 289 280

B. Graphs:

TRIBUTARY RIVERS Total Dissolved Solids 2500

2000

1500 mg/L 1000

500

TOTAL DISSOLVED SOLIDS

Total dissolved solids (TDS) is a measure of the amount of dissolved materials in the water which consist of inorganic salts and dissolved materials. In natural waters, salts are chemical compounds comprised of anions such as carbonates, chlorides, sulfates, and nitrates and cations such as potassium (K), sodium (Na), calcium (Ca), and magnesium (Mg). The concentration of TDS in the water is expressed in milligrams per liter (mg/L). In many instances resource agencies use the terms TDS and salinity interchangeably, since these ions are typically in the form of salts. Measuring total dissolved solids is a way to estimate the suitability of water for irrigation and drinking. This is an important parameter for drinking water because high TDS values may result in a ‗salty‘ taste to the water (http://cals.arizona.edu/watershedsteward/resources/docs/ guide29WaterQuality.pdf).

DENR has no set Class C criterion for TDS but for Class A (for public water supply requiring complete treatment), the maximum permissible level is at 1000 mg/L.

In the lake, the computed annual average TDS levels from 2009 to 2012 ranged from 170 to 698 mg/L wherein the lowest was recorded in Stn. II (East Bay) in 2012 and the highest was in Stn. IV (Central Bay) in 2010.

In the tributary rivers, the annual average TDS levels in all of the stations from 2009 to 2012 were below 1,000 mg/L except those obtained in Stn. 10 (San Cristobal River) in 2009 and 2011 at 1,093 and 2,324 mg/L, respectively.

LAGUNA DE BAY Total Hardness, mg CaCO3/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 97 188 106 139 Stn. II (East Bay) 82 140 97 117 Stn. IV (Central Bay) 91 158 111 126 Stn. V (Northern West Bay) 92 193 106 114 Stn. VIII (South Bay) 89 113 103 133 Stn. XV San Pedro (West Bay) * * * 117 Stn. XVI Sta Rosa (West Bay) * * * 133 Stn. XVII Fish Sanctuary (Central Bay) * * * 119 Stn. XVIII Pagsanjan (East Bay) * * * 110

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Total Hardness – none

B. Graphs

LAGUNA DE BAY Total Hardness (TH)

200 180 160 140

120 /L 3 100 80

60 mg CaCO 40 20 0 2009 2010 2011 2012

TRIBUTARY RIVERS Total Hardness, mg CaCO3/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 143 157 138 209 2 Bagumbayan River (Taguig) 201 220 179 211 3 Buli Creek (Taguig) 167 167 157 190 Mangangate River 4 (Muntinlupa) –Downstream 169 182 146 155 Mangangate River 4U (Muntinlupa) –Upstream * * * 174 Tunasan River (Muntinlupa) 5 –Downstream 181 201 175 212 Tunasan River (Muntinlupa) 5U –Upstream * * * 193 6 San Pedro River (T2) 174 209 213 215 7 Biñan River * * 175 235 Sta. Rosa River – 8 Downstream * * 220 227 Notes: Sta. Rosa River – 8M Midstream * * * 190 8U Sta. Rosa River – Upstream * * * 182 Sampling Frequency – Once a month 9 Cabuyao River 187 196 195 221 DENR Class C criterion for Total 10 San Cristobal River (T3) 163 174 168 230 Hardness – none 11 San Juan River (T5) 180 177 176 202 12 Molawin Creek (Los Baños) * * 142 205 * No sampling done 13 Bay River (T9) 182 177 184 213 14 Pila River * * 105 149 15 Sta. Cruz River (T6) 87 101 95 158 16 Pagsanjan River (T8) 58 73 42 102 17 Pangil River – Downstream 55 67 47 85 17U Pangil River – Upstream * * * 95 18 Siniloan River 53 71 45 104 Sta. Maria River – 19 Downstream * * 79 120 19U Sta. Maria River – Upstream * * * 100 20 Jala-jala River * * * 211 21 Pililla River * * 107 167 22 Tanay River – Downstream 205 198 189 213 22U Tanay River – Upstream * * * 194 23 Baras River * * 247 208 Morong River – 24 Downstream 220 205 201 236 24U Morong River – Upstream * * * 232 Manggahan Floodway 25 (Taytay) 143 149 131 169 26 Sapang Baho River (Cainta) 153 173 137 175

B. Graphs:

TRIBUTARY RIVERS Total Hardness 300

250

200 /L

3 150

mgCaCO 100

TOTAL HARDNESS

Hardness is predominantly caused by divalent cations such as calcium, magnesium, alkaline earth metal such as iron, manganese, strontium, etc. The total hardness is defined as the sum of calcium and magnesium concentrations, both expressed as CaCO3 in mg/L. Carbonates and bicarbonates of calcium and magnesium cause temporary hardness. Sulphates and chlorides cause permanent hardness.

Hardness of water prevents lather formation with soap rendering the water unsuitable for bathing and washing. It forms scales in boilers, making it unsuitable for industrial usage (http://ces.iisc.ernet.in/energy/monograph1/Methpage1.html).

DAO 34 has no Class C criterion for Total Hardness. Among the stations monitored in the lake from 2009 to 2012, Stn. V (Northern West Bay) in 2010 yielded the highest annual average total harness concentration at 193 mg CaCO3/L, whereas the lowest was in Stn. II (East Bay) in 2009 at 82 mg CaCO3/L.

In the tributary rivers, the highest and lowest among the recorded annual average total hardness levels were both recorded in 2011 at 247 mg CaCO3/L in Stn 23 (Baras River) and at 42 mg CaCO3/L in Stn. 16 (Pagsanjan River), respectively.

LAGUNA DE BAY Total Suspended Solids, mg/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 32 32 34 54 Stn. II (East Bay) 40 39 40 33 Stn. IV (Central Bay) 52 14 24 41 Stn. V (Northern West Bay) 48 32 37 46 Stn. VIII (South Bay) 58 57 74 38 Stn. XV San Pedro (West Bay) * * * 39 Stn. XVI Sta Rosa (West Bay) * * * 49 Stn. XVII Fish Sanctuary (Central Bay) * * * 37 Stn. XVIII Pagsanjan (East Bay) * * * 67

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Total Suspended Solids – none (annual average)

B. Graphs

LAGUNA DE BAY Total Suspended Solids (TSS)

75 70 65 60 55 50 45 40 35

30 mg/L 25 20 15 10 5 0 2009 2010 2011 2012

TRIBUTARY RIVERS Total Suspended Solids, mg/L

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 41 57 106 92 2 Bagumbayan River (Taguig) 36 514 40 25 3 Buli Creek (Taguig) 63 107 62 34 Mangangate River 4 (Muntinlupa) -Downstream 22 42 27 25 Mangangate River 4U (Muntinlupa) -Upstream * * * 30 Tunasan River (Muntinlupa) 5 -Downstream 260 58 77 63 Tunasan River (Muntinlupa) 5U -Upstream * * * 28 6 San Pedro River (T2) 38 34 186 40 7 Biñan River * * 21 165 Sta. Rosa River - 8 Downstream * * 33 36 Notes: 8M Sta. Rosa River - Midstream * * * 67 8U Sta. Rosa River - Upstream * * * 19 Sampling Frequency - Once a month 9 Cabuyao River 39 14 20 24 DENR Class C criterion for TSS – 10 San Cristobal River (T3) 126 53 57 45 none (annual average) 11 San Juan River (T5) 101 8 24 36 12 Molawin Creek (Los Baños) * * 26 33 * No sampling done 13 Bay River (T9) 48 53 49 36 14 Pila River * * 52 53 15 Sta. Cruz River (T6) 10 10 14 14 16 Pagsanjan River (T8) 15 12 15 13 17 Pangil River - Downstream 10 17 11 13 17U Pangil River - Upstream * * * 12 18 Siniloan River 28 49 28 22 Sta. Maria River - 19 Downstream * * 33 39 19U Sta. Maria River - Upstream * * * 28 20 Jala-jala River * * * 14 21 Pililla River * * 15 16 22 Tanay River - Downstream 21 42 20 18 22U Tanay River - Upstream * * * 18 23 Baras River * * 27 30 24 Morong River - Downstream 22 35 136 32 24U Morong River - Upstream * * * 58 Manggahan Floodway 25 (Taytay) 31 30 209 55 26 Sapang Baho River (Cainta) 23 16 47 30

B. Graphs: TRIBUTARY RIVERS Total Suspended Solids 600

500

400

300 mg/L

200

100

TOTAL SUSPENDED SOLIDS

Suspended solids are particles of sand, silt, clay, and organic material including plankton that move with the water. Suspended solids are usually measured as a concentration in milligrams per liter (mg/L).

Suspended solids reduce visibility and absorb light, which can increase the water temperature and reduce photosynthesis. Impeding aquatic plant photosynthesis reduces the amount of food, habitat and dissolved oxygen. (http://www.stormwaterx. com/Resources/IndustrialPollutants/TSS.aspx). . Water with high-suspended solids is unsatisfactory for bathing, industrial and other purposes. High levels of suspended solids can cause problems for aquatic organisms because it can reduce visibility, thus, making it hard for fish to find prey (http:// cals.arizona.edu/watershedsteward/resources/docs/guideWaterQuality.pdf). The number of filter-feeding invertebrates will also decline due to clogged feeding mechanisms. As the fish may likewise suffer clogging and abrasive damage to gills and other respiratory surfaces, the abrasion of the gill tissues will trigger excess mucous secretion, decrease resistance to disease, and a reduction or complete cessation of feeding (http://www.sabah.gov.my/jpas/ Assessment/eia/sp-eias/Benta/AppEwater.pdf).

In DAO 34, the Class C water quality criterion for total suspended solids (TSS) is that the increase over the natural background concentration should not be more than 30 mg/L. For the computed annual mean of TSS, there was no set criterion.

From 2009 to 2012, Stn. VIII (South Bay) in 2011 registered the highest annual average TSS in the lake at 74 mg/L while Stn IV (Central Bay) in 2010 had the lowest at 14 mg/L.

The highest among the computed annual means in the tributary rivers for TSS from 2009 to 2012 was 514 mg/L in Stn. 4 (Bagumbayan River) in 2010 and the lowest was in Stn 11 (San Juan River) at 8 mg/L also in 2010.

LAGUNA DE BAY Transparency, centimeters

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 48 47 58 36 Stn. II (East Bay) 44 29 35 46 Stn. IV (Central Bay) 53 50 67 50 Stn. V (Northern West Bay) 50 47 58 39 Stn. VIII (South Bay) 39 37 39 44 Stn. XV San Pedro (West Bay) * * * 45 Stn. XVI Sta Rosa (West Bay) * * * 44 Stn. XVII Fish Sanctuary (Central Bay) * * * 51 Stn. XVIII Pagsanjan (East Bay) * * * 47

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Transparency - none

B. Graphs

LAGUNA DE BAY Transparency

75 70 65 60 55 50 45 40 35 30 25 20

15 centimeters 10 5 0 2009 2010 2011 2012 Stn. I (Central West Bay) Stn. II (East Bay) Stn. IV (Central Bay) Years Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay)

TRANSPARENCY

Transparency or Secchi depth is a measure of how deep the light penetrates into the water column and therefore it is an indication of water clarity. This measurement as an alternative to measuring turbidity, is obtained by lowering a black and white secchi disk into the water and recording the depth from the time that it is visible and until it is no longer visible. Transparency is directly affected by the level of suspended particles and dissolved materials in the water. When assessed along with other parameters such as chlorophyll-a, transparency measurements give us useful insight into the biological productivity in a lake, and ultimately its water quality conditions (http://www.micorps. net/documents/SecchiFactsheet.pdf).

The annual average transparency of the lake from 2009 to 2012 ranged from 29 to 67 centimeters with the lowest obtained in Stn. II (East Bay) in 2010 and the highest recorded in Stn. IV (Central Bay) in 2011.

LAGUNA DE BAY Turbidity, NTU

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 37 32 33 44 Stn. II (East Bay) 38 25 36 34 Stn. IV (Central Bay) 38 12 29 41 Stn. V (Northern West Bay) 51 30 45 48 Stn. VIII (South Bay) 55 26 51 36 Stn. XV San Pedro (West Bay) * * * 36 Stn. XVI Sta Rosa (West Bay) * * * 47 Stn. XVII Fish Sanctuary (Central Bay) * * * 34 Stn. XVIII Pagsanjan (East Bay) * * * 31

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

DENR Class C criterion for Turbidity - none

B. Graphs

LAGUNA DE BAY Turbidity

60 55 50 45 40 35 30

25 NTU 20 15 10 5 0 2009 2010 2011 2012

Stn. I (Central West Bay) Stn. II (East Bay)Years Stn. IV (Central Bay) Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay)

Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay)

TRIBUTARY RIVERS Turbidity, NTU

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 15 69 122 112 2 Bagumbayan River (Taguig) 34 57 30 12 3 Buli Creek (Taguig) 47 51 34 17 Mangangate River 4 (Muntinlupa) -Downstream 17 30 14 20 Mangangate River 4U (Muntinlupa) -Upstream * * * 10 Tunasan River (Muntinlupa) 5 -Downstream 55 50 67 29 Tunasan River (Muntinlupa) 5U -Upstream * * * 17 6 San Pedro River (T2) 21 19 35 15 7 Biñan River * * 22 51 Sta. Rosa River - 8 Downstream * * 14 36 Notes: 8M Sta. Rosa River - Midstream * * * 19 8U Sta. Rosa River - Upstream * * * 8 Sampling Frequency - Once a month 9 Cabuyao River 21 8 14 12 DENR Class C criterion for DO - 10 San Cristobal River (T3) 93 37 13 20 5.0 mg/l 11 San Juan River (T5) 202 5 6 35 12 Molawin Creek (Los Baños) * * 31 27 * No sampling done 13 Bay River (T9) 31 26 27 24 14 Pila River * * 39 38 15 Sta. Cruz River (T6) 12 10 11 10 16 Pagsanjan River (T8) 15 10 18 12 17 Pangil River - Downstream 8 11 10 10 17U Pangil River - Upstream * * * 4 18 Siniloan River 23 33 28 20 Sta. Maria River - 19 Downstream * * 33 40 19U Sta. Maria River - Upstream * * * 17 20 Jala-jala River * * * 12 21 Pililla River * * 41 17 22 Tanay River - Downstream 10 22 27 10 22U Tanay River - Upstream * * * 6 23 Baras River * * 33 27 24 Morong River - Downstream 17 47 127 60 24U Morong River - Upstream * * * 56 Manggahan Floodway 25 (Taytay) 16 37 97 76 26 Sapang Baho River (Cainta) 18 20 35 20

B. Graphs:

TRIBUTARY RIVERS Turbidity 250

200

150 mg/L 100

TURBIDITY

Turbidity is a significant indicator of overall water quality. It is an expression of optical property wherein light is scattered by suspended particles present in water (Tyndall effect) and is measured in Nephelometric Turbidity Units (NTUs).

Suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter; plankton and other microscopic organisms cause turbidity in water. http://ces.iisc.ernet.in/energy/monograph1/Methpage1.html.

Water that has high turbidity appears cloudy or opaque. High turbidity can cause increased water temperatures because suspended particles absorb more heat and can also reduce the amount of light penetrating the water. High levels of turbidity make it difficult for fish to find prey due to high levels of suspended solids. Turbidity due to a large volume of suspended sediment will reduce light penetration, thereby suppressing photosynthetic activity of phytoplankton,and macrophytes, especially those farther from the water surface. If turbidity is largely due to algae, light will not penetrate deeply onto the water and primary production will be limited to the uppermost layer of the water. Overall, excess turbidity leads to fewer photosynthetic organisms available to serve as food sources for the aquatic animals. If turbidity is largely due to organic particles, dissolved oxygen depletion may occur in the water body. (http://www.sabah.gov.my/ jpas/Assessment/eia/sp-eias/Benta/AppEwater.pdf). . The DENR has no set Class C criterion for turbidity. For the 4-year monitoring period from 2009 to 2012, the annual average turbidities in the lake varied from 12 NTU (recorded in Stn. IV-Central Bay in 2010) to 55 NTU (obtained in Stn. VIII-South Bay in 2009).

The three (3) tributary river stations which indicated very high annual average turbidity values of more than 100 NTU from 2009 to 2012 were Stn. 11 (San Juan River) in 2009 at 202 NTU, Stn. 24 (Morong River-Downstream) in 2011 at 127 NTU, and Stn. 1 (Marikina River) at 122 NTU in 2011 and 112 NTU in 2012. Stn. 17U (Pangil River- Upstream) yielded the lowest annual average turbidity among the tributary river stations at 4 NTU in 2012.

LAGUNA DE BAY Phytoplankton, counts/mL

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 14832 29345 51920 57903 Stn. II (East Bay) 13557 19178 26164 13212 Stn. IV (Central Bay) 11097 40075 43933 25299 Stn. V (Northern West Bay) 19178 17257 33404 25750 Stn. VIII (South Bay) 17309 15106 23437 31286 Stn. XV San Pedro (West Bay) * * * 46300 Stn. XVI Sta Rosa (West Bay) * * * 120829 Stn. XVII Fish Sanctuary (Central Bay) * * * 25313 Stn. XVIII Pagsanjan (East Bay) * * * 22164

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

B. Graphs

TRIBUTARY RIVERS Phytoplankton, counts/mL

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River * * 8,774 73,044 Bagumbayan River 2 (Taguig) * * 245,065 295,386 3 Buli Creek (Taguig) * * * * Mangangate River 4 (Muntinlupa) -Downstream * * * * Mangangate River 4U (Muntinlupa) -Upstream * * * * Tunasan River (Muntinlupa) 5 -Downstream * * 25,858 50,561 Tunasan River (Muntinlupa) 5U -Upstream * * * 105,917 6 San Pedro River (T2) * * 359,283 242,813 7 Biñan River * * 121,155 102,612 Sta. Rosa River - 8 Downstream * * 100,890 149,479 Notes: Sta. Rosa River - 8M Midstream * * * 34,881 8U Sta. Rosa River - Upstream * * * 15,626 Sampling Frequency - Once a month 9 Cabuyao River * * 59,934 320,861 10 San Cristobal River (T3) * * 233,663 129,698 * No sampling done 11 San Juan River (T5) * * 115,176 40,023 12 Molawin Creek (Los Baños) * * 4,294 17,917 13 Bay River (T9) * * 9,963 54,687 14 Pila River * * 15,737 26,390 15 Sta. Cruz River (T6) * * 54,252 55,813 16 Pagsanjan River (T8) * * 38,141 17,512 17 Pangil River - Downstream * * 7,177 951 17U Pangil River - Upstream * * * 1,077 18 Siniloan River * * 24,007 16,754 Sta. Maria River - 19 Downstream * * 80,929 43,449 Sta. Maria River - 19U Upstream * * * 14,107 20 Jala-jala River * * * 32,125 21 Pililla River * * 9,024 85,275 22 Tanay River - Downstream * * 3,640 6,131 22U Tanay River - Upstream * * * 34,082 23 Baras River * * 5,085 67,778 Morong River - 24 Downstream * * 309,863 421,926 24U Morong River - Upstream * * * 184,570 Manggahan Floodway 25 (Taytay) * * 59,986 953,900 Sapang Baho River 26 (Cainta) * * 14,375 4,443,555

B. Graphs:

TRIBUTARY RIVERS Phytoplankton Counts 1,000,000

900,000

800,000

700,000

600,000

500,000

counts/ml 400,000

300,000

200,000

100,000

PHYTOPLANKTON

Phytoplankton is also known as algae and it refers to free-floating plants which inhabit the illuminated surface waters of the sea, estuaries, lakes and ponds. Phytoplankton are mostly unicellular and their photosynthetic activity in order to reproduce is limited to the maximum depth to which light can penetrate into the water.

Phytoplankton have a critical role in primary production, nutrient cycling, and food webs and make up a significant proportion of the primary production in aquatic systems (Dawes 1998 as cited in http://nerrs.noaa.gov/doc/siteprofile/acebasin/html/biores/phyto/pytext.htm). Phytoplankton are the food source for numerous aquatic animals, especially the zooplankton which can significantly decrease phytoplankton density.

Phytoplankton growth and productivity are affected by several factors which are called limiting factors. These limiting factors include light, temperature, circulation, grazing, and nutrients. The same with the other factors which affect phytoplankton production, the effect of grazers is seasonal. Phytoplankton experience the greatest productivity when they encounter their optimal light and nutrient conditions. With adequate nutrients, phytoplankton growth and productivity increases with increasing light levels until a certain light level is reached. At this point photosynthesis is at its maximum and further photosynthesis is inhibited with increasing light levels (http://nerrs.noaa.gov/doc/siteprofile/acebasin/html/ biores/phyto/pytext.htm). . The phytoplankton genera found in Laguna de Bay and its tributary rivers belonged to the following classes: Class Cyanophyceae (blue-green algae), Class Chlorophyceae (green algae), Class Bacillariophyceae (diatoms) and Class Pyrrophyceae (dinoflagellates).

From 2009 to 2012, Class Chlorophyceae (green algae) was the most diverse in the lake but the most dominant genera were from Class Cyanophyceae (blue-green algae) and Class Bacillariophyceae (diatoms). The phytoplankton genera which usually had the highest counts during the 4-year monitoring period were Melosira sp. (diatoms), Microcystis sp. (blue-green algae) and Stephanodiscus sp. (diatoms). The lowest computed annual phytoplankton counts in the lake was in Stn. IV (Central Bay) at 11,097 counts/ml recorded in 2009 and the highest was obtained in Stn. XVI (West Bay-Sta Rosa) at 120,829 counts/ml in 2012.

The analysis of water samples for phytoplankton counts in the tributary rivers started in 2011. From among the 34 tributary river stations, 11 of them had very high annual phytoplankton counts exceeding 100,000 counts/ml and these are Stn. 2-Bagumbayan River (at 245,065 counts/ml in 2009 and 295,386 counts/ml in 2010), Stn. 5U-Tunasan River Upstream (at 105,917 counts/ml in 2012), Stn. 6-San Pedro River (at 359,283 counts/ml in 2011 and 242,813 counts/ml in 2012), Stn. 8-Sta.Rosa River Downstream (at 100,890 counts/ml in 2011 and 149,479 counts/ml in 2012), Stn. 8-Sta. Rosa River Downstream (at 100,890 counts/ml in 2011 and 149,479 counts/ml in 2012), Stn. 9-Cabuyao River (at 320,861 counts/ml in 2012), Stn. 10- San Cristobal River (at 233,663 counts/ml in 2011 and 129,698 counts/ml in 2012), Stn. 11-San Juan River (at 115,176 counts/ml in 2011), Stn. 24-Morong River Downstream (at 309,863 counts/ml in 2011 and 421,926 counts/ml in 2012), Stn. 24U-Morong River Upstream (at 184,570 counts/ml in 2012), Stn. 25-Manggahan Flooodway (at 953,900 counts/ml in 2012) and Stn. 26-Sapang Baho River (at 4,443,555 counts/ml in 2012). The identified abundant phytoplankton genera in these rivers were Nitzschia sp. (diatom), a polluted water indicator. The predominance of Microcystis sp. (blue-green alga) in November, 2012 was responsible for the very high annual mean phytoplankton counts in Stns. 25 and 26 in 2012. The lowest annual mean phytoplankton counts from 2009 to 2012 was 951 counts/ml in Stn. 17 (Pangil River- Downstream) in 2012.

LAGUNA DE BAY Zooplankton, counts/L

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 25 54 60 33 Stn. II (East Bay) 17 46 28 21 Stn. IV (Central Bay) 23 40 45 36 Stn. V (Northern West Bay) 15 201 44 33 Stn. VIII (South Bay) 14 33 41 26 Stn. XV San Pedro (West Bay) * * * 34 Stn. XVI Sta Rosa (West Bay) * * * 21 Stn. XVII Fish Sanctuary (Central Bay) * * * 17 Stn. XVIII Pagsanjan (East Bay) * * * 16

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

B. Graphs

LAGUNA DE BAY Zooplankton Counts

200 190 180 170 160 150 140 130 120 110 100 90 80 70

counts/liter 60 50 40 30 20 10 0 2009 2010 2011 2012 Stn. I (Central West Bay) Stn. II (East Bay) Stn. IV (Central Bay) Years Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay)

ZOOPLANKTON

Zooplankton is the common name given to many small species of animals found in fresh and marine waters. Zooplankton is a Greek word which means "wandering animals." Most of these animals are so minute that they can only be seen using a microscope. Zooplankton floats in the water column and drifts with the currents because of their limited powers of locomotion. Like phytoplankton, they are usually denser than water and constantly sink by gravity to lower depths (http://www.edc.uri.edu/restoration/ html/gallery/invert/zoo.htm).

The zooplankton population in Laguna de Bay belonged to three major groups: rotifers, cladocerans and copepods. Copepods are crustaceans with a tough exoskeleton composed of calcium carbonate, and their bodies are divided into three sections: the head, thorax, and abdomen. Two antennae protrude from the head and aid in swimming, while two to four pairs of appendages extend from the thorax. Copepods and other zooplankton feed on phytoplankton and are the first link between the primary producers and larger animals. Zooplankton is a vital component of freshwater food webs. The smallest zooplankton are eaten by the larger zooplankton which, in turn, are eaten by small fish, aquatic insects and so on (http://www.doc.govt.nz/conservation/ native-animals/invertebrates/zooplankton/).

Of the three (3) groups of zooplankton in the lake, the most abundant from 2009 to 2012 were the copepods and the most diverse were the rotifers. The copepods comprised of their immature stages and the following genera: Mesocyclops, Thermocyclops, Arctodiaptomus and Diaptomus spp.. The identified rotifers included Brachionus, Filinia, Keratella, Lecane and Tricocerca spp. while the cladocerans consisted of Bosmina, Moina, Diaphanosoma and Chydorus spp.. Based on the computed annual average total zooplankton counts in the lake, the lowest was at 14 counts/liter in Stn. VIII (South Bay) in 2009 and the highest was 201 counts/liter in Stn. V (Northern West Bay) in 2010.

LAGUNA DE BAY Benthos, individuals/sq.m.

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 149 369 1150 500 Stn. II (East Bay) 197 185 409 238 Stn. IV (Central Bay) 108 179 1107 310 Stn. V (Northern West Bay) 979 513 845 551 Stn. VIII (South Bay) 114 254 699 234 Stn. XV San Pedro (West Bay) * * * 843 Stn. XVI Sta Rosa (West Bay) * * * 322 Stn. XVII Fish Sanctuary (Central Bay) * * * 528 Stn. XVIII Pagsanjan (East Bay) * * * 213

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month

B. Graphs

LAGUNA DE BAY Benthos

1200 1100 1000 900 800 700 600 500 400 individuals/sq.m. 300 200 100 0 2009 2010 2011 2012 Stn. I (Central West Bay) Stn. II (East Bay) Stn. IV (Central Bay) Years Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay)

BENTHOS

"Benthos" refers to the benthic invertebrate community, which is a group of animals that live on or in the bottom sediments of water bodies such as lakes and rivers. Benthic macroinvertebrates include crustaceans, mollusks, worms, and many species of insect larva such as mayflies, stoneflies, caddisflies, and beetles. The abundance of macroinvertebrates belonging to the orders Ephemeroptera, Plecoptera, and Trichoptera should be noted because for being highly sensitive to pollution, they are often used as water quality indicators. Their presence indicates a high quality of water, while their absence suggests water may be polluted. (http://www.cotf.edu/ete/modules/ waterq3/WQassess2a.html)

Benthos are easier to capture than fish, and easier to identify than algae or protozoa. Benthos cannot move around like fish that they are less able to escape the effects of sediment and other pollutants that diminish water quality. Thus, benthos can give us reliable information on stream and lake water quality because their long life cycles will allow studies conducted by aquatic ecologists to determine any decline in environmental quality (http://www.dnr.state.md.us/irc/docs/00004176.pdf).

The collection of benthos samples in Laguna de Bay and in the tributary river stations by LLDA is usually done using an ekman dredge. But in river stations that are shallow with water depth of less than one (1) foot deep, the surber sampler is used instead of the ekman dredge.

The benthos identified in Laguna de Bay and its tributaries from 2009 to 2012 are classified into five (5) groups: Gastropoda, Crustacea, Insecta, Oligochaeta and Pelecypoda. In the lake, the most dominant genera of benthic macroinvertebrates were Cypricercus sp. (crustacean) in 2009; and Thiara sp. (gastropod) and Cypricercus sp. in 2010, 2011 and 2012. Among the nine (9) stations in the lake monitored in 2009 up to 2012, the lowest and highest annual average benthos population were recorded both in Stn. IV (Central Bay) at 108 individuals/sq. m. in 2009 and 1,107 individuals/sq. m. in 2011.

LAGUNA DE BAY Total Coliform, MPN/100 mL

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 295 56 55 200 Stn. II (East Bay) 127 75 266 222 Stn. IV (Central Bay) 147 36 213 375 Stn. V (Northern West Bay) 438 55 1552 1528 Stn. VIII (South Bay) 1096 188 2100 1373 Stn. XV San Pedro (West Bay) - - - 955 Stn. XVI Sta Rosa (West Bay) - - - 358 Stn. XVII Fish Sanctuary (Central Bay) - - - 212 Stn. XVIII Pagsanjan (East Bay) - - - 318

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month All data presented are computed annual geomeans

DENR Class C criterion for Total Coliform – 5,000 MPN/100 ml

B. Graphs

LAGUNA DE BAY Total Coliform

5000 4500 4000 3500 3000 2500 2000

1500 MPN/100 MPN/100 ml 1000 500 0 2009 2010 2011 2012 Stn. I (Central West Bay) Stn. II (East Bay) Stn. IV (Central Bay) Years Stn. V (Northern West Bay) Stn. VIII (South Bay) Stn. XV San Pedro (West Bay) Stn. XVI Sta Rosa (West Bay) Stn. XVII Fish Sanctuary (Central Bay) Stn. XVIII Pagsanjan (East Bay) DENR Class C Criterion

TRIBUTARY RIVERS Total Coliform, MPN/100 mL

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 2.8E+06 1.7E+06 4.9E+05 1.6E+06 2 Bagumbayan River (Taguig) 1.4E+15 4.3E+06 7.3E+06 8.2E+06 3 Buli Creek (Taguig) 9.6E+14 8.3E+06 2.8E+07 1.0E+07 Mangangate River 4 (Muntinlupa) -Downstream 3.0E+11 2.7E+06 6.0E+06 4.1E+06 Mangangate River 4U (Muntinlupa) -Upstream * * * 3.3E+06 Tunasan River (Muntinlupa) 5 -Downstream 2.3E+11 1.1E+07 1.3E+07 2.3E+07 Tunasan River (Muntinlupa) 5U -Upstream * * * 3.2E+05 6 San Pedro River (T2) 2.7E+09 1.5E+06 1.7E+06 3.1E+06 7 Biñan River * * 8.8E+05 3.1E+06 Sta. Rosa River - 8 Downstream * * 9.2E+06 7.3E+06 Notes: 8M Sta. Rosa River - Midstream * * * 5.4E+06 8U Sta. Rosa River - Upstream * * * 7.8E+05 Sampling Frequency - Once a month 9 Cabuyao River 7.5E+07 1.7E+06 1.9E+06 2.4E+06 All data presented are computed 10 San Cristobal River (T3) 1.2E+09 7.0E+06 3.2E+06 8.5E+06 annual geomeans 11 San Juan River (T5) 6.4E+05 9.4E+04 1.9E+05 4.7E+05 DENR Class C criterion for Total 12 Molawin Creek (Los Baños) * * 9.6E+04 7.1E+04 Coliform – 5,000 MPN/100 ml 13 Bay River (T9) 7.3E+05 1.1E+05 4.7E+05 4.1E+05 14 Pila River * * 1.8E+05 1.4E+05 * No sampling done 15 Sta. Cruz River (T6) 5.7E+04 1.7E+04 1.1E+05 1.3E+05 16 Pagsanjan River (T8) 3.7E+04 1.4E+04 5.4E+04 3.4E+04 17 Pangil River - Downstream 8.8E+04 3.0E+05 1.2E+05 1.7E+05 17U Pangil River - Upstream * * - 8.1E+03 18 Siniloan River 8.8E+04 4.4E+04 6.9E+04 5.7E+04 Sta. Maria River - 19 Downstream * * 9.9E+04 1.0E+05 19U Sta. Maria River - Upstream * * - 8.7E+03 20 Jala-jala River * * 1.9E+05 6.7E+05 21 Pililla River * * 2.1E+05 9.4E+04 22 Tanay River - Downstream 2.3E+05 5.2E+05 3.4E+05 2.2E+05 22U Tanay River - Upstream * * - 4.5E+04 23 Baras River * * 3.0E+05 3.9E+05 24 Morong River - Downstream 2.9E+05 1.9E+05 4.3E+04 1.7E+05 24U Morong River - Upstream * * - 1.4E+05 Manggahan Floodway 25 (Taytay) 7.4E+05 4.5E+05 1.7E+05 4.5E+05 26 Sapang Baho River (Cainta) 4.7E+06 1.7E+06 1.4E+06 2.6E+06

B. Graphs:

TOTAL COLIFORM

Coliform bacteria are microscopic organisms that originate in the intestinal tract of warm-blooded animals and are also present in soil and vegetation. Total coliform are generally harmless but their presence in water would indicate the possibility of contamination by disease-causing bacteria, viruses or parasites. Most coliform bacteria enter natural streams by direct deposition of waste in the water and runoff from areas with high concentrations of animals or humans. Domesticated animals contribute heavily to the bacterial population. Diseases that may be present in water tested positive for coliform bacteria include typhoid fever, cholera, hepatitis, dysentery, diarrhea, giardiasis, and hemolytic uremic syndrome (https://extension.usu.edu/files/ publications/factsheet/NR_WQ_2005-20.pdf). Total coliform is measured using the Multiple Tube Fermentation technique and the result of analysis is expressed as the Most Probable Number (MPN).

The DENR‘s Class C criterion for total coliform is set at 5,000 MPN/100 ml.

The annual geomean total coliform concentrations in all lake stations from 2009 to 2013 which ranged from 55 to 2,100 MPN/100 ml passed the DENR Class C criterion. On the other hand, all river stations had annual geomean total coliform concentrations exceeding the 5,000 MPN/100 ml Class C criterion throughout the 4-year monitoring period with the lowest at 8,123 MPN/100 ml in Stn 17U (Pangil River Upstream) in 2012 and the highest at 1,423,305,032,753,950 MPN/100 ml in Stn. 2 (Bagumbayan River) in 2009.

LAGUNA DE BAY Fecal Coliform, MPN/ 100 mL

A. Water Quality Data:

Annual Averages Laguna de Bay Water Quality Monitoring Stations Monitoring Stations 2009 2010 2011 2012 Stn. I (Central West Bay) 165 51 20 11 Stn. II (East Bay) 66 70 26 8 Stn. IV (Central Bay) 97 40 179 15 Stn. V (Northern West Bay) 241 51 233 147 Stn. VIII (South Bay) 694 157 534 200 Stn. XV San Pedro (West Bay) * * * 217 Stn. XVI Sta Rosa (West Bay) * * * 36 Stn. XVII Fish Sanctuary (Central Bay) * * * 54 Stn. XVIII Pagsanjan (East Bay) * * * 151

Notes: * No data - not yet included in the LLDA's Water Quality Monitoring Program

Sampling Frequency - Once a month All data presented are computed annual geomeans

DENR Class C criterion for Fecal Coliform - none

B. Graphs

LAGUNA DE BAY Fecal Coliform

700 650 600 550 500 450 400 350 300 250

MPN/100 MPN/100 ml 200 150 100 50 0 2009 2010 2011 2012

TRIBUTARY RIVERS Fecal Coliform, MPN/100 mL

A. Water Quality Data Monitoring Stations Annual Averages Tributary Rivers Water Quality Station Locations Monitoring Stations 2009 2010 2011 2012 No. 1 Marikina River 1.5E+06 1.1E+06 2.0E+05 6.4E+05 2 Bagumbayan River (Taguig) 1.1E+15 2.9E+06 4.7E+06 5.2E+06 3 Buli Creek (Taguig) 6.8E+14 8.7E+06 1.4E+07 5.9E+06 Mangangate River 4 (Muntinlupa) -Downstream 1.3E+11 2.6E+06 1.6E+06 1.9E+06 Mangangate River 4U (Muntinlupa) -Upstream * * * 1.9E+06 Tunasan River (Muntinlupa) 5 -Downstream 1.8E+11 1.1E+07 7.5E+06 1.2E+07 Tunasan River (Muntinlupa) 5U -Upstream * * * 1.3E+05 6 San Pedro River (T2) 1.8E+09 1.5E+06 7.9E+05 1.3E+06 7 Biñan River * * 7.8E+05 7.0E+05 Sta. Rosa River - 8 Downstream * * 2.4E+06 1.6E+06 Notes: 8M Sta. Rosa River - Midstream * * * 2.8E+06 8U Sta. Rosa River - Upstream * * * 6.2E+05 Sampling Frequency - Once a month 9 Cabuyao River 4.7E+07 1.5E+06 9.9E+05 1.4E+06 All data presented are computed 10 San Cristobal River (T3) 1.1E+09 7.0E+06 2.0E+06 2.7E+06 annual geomeans 11 San Juan River (T5) 5.6E+05 8.6E+04 1.6E+05 1.9E+05 DENR Class C criterion for Fecal 12 Molawin Creek (Los Baños) * * 3.5E+04 3.5E+04 Coliform – none 13 Bay River (T9) 5.0E+05 8.0E+04 4.0E+05 1.5E+05 14 Pila River * * 7.2E+04 4.1E+04 * No sampling done 15 Sta. Cruz River (T6) 4.8E+04 1.4E+04 3.2E+04 3.1E+04 16 Pagsanjan River (T8) 3.1E+04 4.1E+04 3.3E+04 1.5E+04 17 Pangil River – Downstream 5.9E+04 2.4E+05 5.7E+04 8.9E+04 17U Pangil River – Upstream * * * 3.9E+03 18 Siniloan River 6.1E+04 4.0E+04 2.6E+04 2.1E+04 Sta. Maria River – 19 Downstream * * 7.8E+04 6.7E+04 19U Sta. Maria River – Upstream * * * 2.5E+03 20 Jala-jala River * * * 3.0E+05 21 Pililla River * * 5.2E+04 4.5E+04 22 Tanay River – Downstream 1.4E+05 4.4E+05 1.7E+05 6.7E+04 22U Tanay River – Upstream * * * 1.4E+04 23 Baras River * * 1.7E+05 1.2E+05 Morong River – 24 Downstream 2.2E+05 1.7E+05 2.7E+04 4.1E+04 24U Morong River – Upstream * * * 4.8E+04 Manggahan Floodway 25 (Taytay) 6.4E+05 3.4E+05 8.7E+04 1.4E+05 26 Sapang Baho River (Cainta) 2.8E+06 1.6E+06 8.2E+04 1.1E+05

B. Graphs:

FECAL COLIFORM

The presence of fecal coliform bacteria in aquatic environments indicates that the water has been contaminated with the fecal material of man or other animals. At the time this occurred, the source water may have been contaminated by pathogens or disease producing bacteria or viruses which can also exist in fecal material. Some waterborne pathogenic diseases include typhoid fever, viral and bacterial gastroenteritis and hepatitis A. The presence of fecal contamination is an indicator that a potential health risk exists for individuals exposed to this water. Fecal coliform bacteria may occur in ambient water as a result of the overflow of domestic sewage or nonpoint sources of human and animal waste (http://www.state.ky.us/nrepc/water/wcpfcol.htm).

There is no set Class C criterion for fecal coliform under DAO 34. Stn. VIII (South Bay) had the highest annual geomean fecal coliform levels in 2009, 2010 and 2011 among the lake stations monitored from 2009 to 2012 at 694, 157 and 534 MPN/ 100 ml, respectively. In 2012, Stn. XV (West Bay-San Pedro) recorded the highest annual geomean fecal coliform level of 217 MPN/100 ml. The lowest annual geomean fecal coliform level in all lake stations for the 4-year monitoring period was at 8 MPN/100 ml obtained in Stn. II (East Bay) in 2012.

The tributary rivers had comparatively much higher annual geomean fecal coliform levels in most of the stations than in the lake from 2009 to 2012 as the concentrations ranged from 2,524 MPN/100 ml to 1,117,310,629,006,070 MPN/100 ml. The lowest fecal coliform computed annual geomean was noted in Stn. 19U (Sta. Maria River- Upstream) in 2012 at 2,524 MPN/100 ml while the highest was in Stn. 2 (Bagumbayan River) in 2009 at 1,117,310,629,006,070 MPN/100 ml.

LAGUNA DE BAY Net Primary Productivity

A. Water Quality Data: West Bay Central Bay East Bay (Binangonan, Rizal) (Pililla, Rizal) (Sta. Cruz, Laguna) Year tons C/ha./yr. tons F/ha./yr. tons C/ha./yr. tons F/ha./yr. tons C/ha./yr. tons F/ha./yr.

2009 3.26 2.61 3.39 2.63 2.25 1.80

2010 8.06 5.38 5.42 4.34 2.87 2.30

2011 4.28 3.42 3.04 2.44 3.36 2.68

2012 2.66 2.12 3.51 2.81 2.82 2.26

B. Graphs:

LAGUNA DE BAY Primary Productivity

10.00 9.00 8.00 7.00 6.00 5.00 4.00 3.00 2.00

tons carbon/hectare/year tons 1.00 0.00 2009 2010 2011 2012

Years West Bay Central Bay East Bay

PRIMARY PRODUCTIVITY

Gross primary productivity is the rate at which solar energy is stored as organic molecules by plants in an ecosystem. On the other hand, the net primary productivity (NPP) reflects the energy that is used by plants as they carryout respiration, and is calculated by subtracting the amount of respiration from the gross primary productivity. The net primary productivity is of interest to ecologists, since this is the amount of energy that is available for use by consumers in an ecosystem and determines the energy budget of the ecosystem. In ecological studies, high primary productivity in an aquatic ecosystem indicates that the ecosystem is ―healthy‖

In bodies of water, the amount of sunlight (solar energy) penetration decreases as the depth increases. This means the rate of photosynthesis and primary productivity also decrease. When sufficient sunlight is no longer is available, producers cannot survive and carryout photosynthesis to produce organic molecules and oxygen.

The compensation depth in a lake is the depth at which the rate of photosynthesis equals the rate of respiration. As a result, net primary productivity is equal to zero at the compensation depth. Because the rate of photosynthesis depends on light intensity, the level of the compensation depth depends on the depth to which a critical amount of light can penetrate into the water. The region above the compensation depth is referred to as the photic zone (euphotic zone), while the region below the compensation depth is referred to as the aphotic zone (http://nrhs.nred.org/download.axd?file=6bc1ca31-dafa- 47bc-bfb3-caf03f60c).

In Laguna de Bay, the primary productivity is measured using the ―Light and Dark‖ Method. The primary productivity measurements provide information on the available natural food supply in the lake at a certain place and time. Based on the lake‘s primary production which is expressed in tons carbon/hectare/year, the corresponding estimates of the lake‘s fish production potential in terms of tons/hectare/year can also be computed.

Among the three (3) primary productivity stations in the lake, the West Bay station had the highest annual average net primary productivities in 2010 and 2011 at 8.06 tons carbon/hectare/year and 4.28 tons carbon/hectare/year, respectively, while Central Bay‘s annual average NPPs were highest in 2009 at 3.39 tons carbon/hectare/year and 2012 at 3.51 tons carbon/hectare/year. The lowest computed annual average NPPs were at the East Bay station in 2009 and 2010 at 2.25 tons carbon/hectare/year and 2.25 tons carbon/hectare/year, respectively; Central Bay station in 2011 at 3.04 tons carbon/hectare/year; and West Bay station in 2012 at 2.66 tons carbon/hectare/year. The estimated fish production potentials of the lake ranged from 1.80 to 2.63 tons/hectare/year in 2009, 2.30 to 5.38 tons carbon/hectare/year in 2010, 2.44 to 3.42 tons carbon/hectare/year in 2011 and 2.12 to 2.81 tons carbon/hectare/year.

SUMMARY

Generally, the water quality of Laguna de Bay from 2009 to 2012 met the DENR Class C criteria based on the computed annual average levels of most of the physicochemical parameters for biochemical oxygen demand (BOD), chloride, dissolved oxygen (DO), nitrate, oil and grease, pH and total coliforms.

Among the lake primary productivity stations in the three (3) bays of Laguna Lake, the most productive on the basis of the computed net primary productions (NPPs) from 2009 to 2012 were the Central Bay station in 2009 and 2012, and the West Bay station in 2010 and 2011. The highest NPP in 2010 at the West Bay coincided with the saltwater intrusion event at that time.

From among the tributary rivers, the stations noted with very poor water quality or always failed the DENR Class C criteria in 2009 up to 2012 were Stns. 1 (Marikina), 2 (Bagumbayan River-Taguig), 3 (Buli Creek-Taguig), 4 (Mangangate River Downstream), 4U (Mangangate River Upstream), 5 (Tunasan River Downstream), 6 (San Pedro River), 7 (Biñan River), 8 (Sta. Rosa River Downstream), 9 (Cabuyao River), 24 (Morong River Downstream), 24U (Morong River Upstream), 25 (Manggahan Floodway-Taytay) and 26 (Sapang Baho River-Cainta) for ammonia; Stns. 1, 2, 3, 4, 4U, 5, 6, 7, 8, 8M , (Sta. Rosa River Midstream), 9, 10 (San Cristobal River), 24, 24U, 25 and 26 for BOD; Stns. 1, 2, 3, 4, 5, 6, 7 ,8, 8M, 9, 10, 25 and 26 for obtaining average annual dissolved oxygen (DO) levels of less than 3 mg/L; Stns. 1, 2, 3, 4, 4U, 5, 5U (Tunasan River Upstream), 6, 7, 8 8M, 8U (Sta. Rosa River Upstream), 9, 10, 11 (San Juan River), 24, 24U, 25 and 26 for inorganic phosphate; Stn. 5 for oil and grease; Stn. 22U (Tanay River Upstream) for pH; and all stations for total coliform. Apparently, the results of the water quality assessments showed that most of the polluted tributary river stations are located at the western and northern parts of the West Bay wherein most of the population and the industrial establishments within the Laguna de Bay Region are concentrated. Thus, pollution control activities must be intensified in these rivers.

The tributary river stations whose annual average water quality parameter levels from 2009 to 2012 consistently conformed with the DENR Class C criteria included Stns. 12 (Molawin Creek-Los Baños), 13 (Bay River), 14 (Pila River), 15 (Sta. Cruz River), 16 (Pagsanjan River), 17 (Pangil River Downstream), 18 (Siniloan River), 19 (Sta. Maria River-Downstream), 21 (Pililla River), 22 (Tanay River-Downstream) and 23 (Baras River) for BOD; all stations for chloride and nitrate; Stns. 13, 15, 16, 17 and 22 for DO; Stns. 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24 and 25 for oil and grease; and all stations except Stn. 22U for pH.

METHODS OF ANALYSIS

PARAMETER METHOD OF ANALYSIS

Alkalinity Titration with Indicator Ammonia Phenol Hypochlorite (Colorimetry) Biochemical Oxygen Demand (BOD) Azide Modification (Dilution Technique) Calcium Hardness EDTA Titration Chemical Oxygen Demand (COD) Dichromate Reflux Method Chloride Argentometric Titration Dissolved Oxygen (DO) Azide Modification (Winkler Method) Inorganic Phosphate Ascorbic Acid Method Nitrate Sodium Salicylate Method Oil and Grease Gravimetric Method (Petroleum Ether Extraction) pH Glass Electrode Method Temperature Mercury-filled Thermometer Total Dissolved Solids (TDS) Gravimetric Method Total Hardness EDTA Titration Total Suspended Solids (TSS) Gravimetric Method Transparency Secchi Disc Turbidity Nephelometric Method Total Coliform Multiple Tube Fermentation Technique Fecal Coliform Multiple Tube Fermentation Technique Phytoplankton Inverted Microscope Method Zooplankton Stereo Microscope Method Benthos Stereo Microscope Method

DENR ADMINISTRATIVE ORDER NO. 34 (Series of 1990)

WATER QUALITY CRITERIA FOR CONVENTIONAL AND OTHER POLLUTANTS CONTRIBUTING TO AESTHETICS AND OXYGEN DEMAND FOR FRESHWATERS (a)

PARAMETER UNIT CLASS C

Color PCU (b)

Temperature(c) oC rise 3 (maximum rise in degree Celsius) pH (range) 6.5-8.5

Dissolved Oxygen (d) % saturation 60 (minimum) mg/L 5.0

5-Day 20oC BOD mg/L 7(10)

Total Suspended Solids mg/L (e)

Total Dissolved Solids mg/L -

Oil and Grease mg/L 2 (Petroleum Ether Extracts)

Nitrate as Nitrogen mg/L 10 (f)

Phosphate as Phosphorus mg/L 0.4 (g)

Total Coliform MPN/100ml 5,000 (h)

Chloride as Cl- mg/L 350

Footnotes

(a) - Except as otherwise indicated, the numerical limits are yearly average values. Values enclosed in parentheses are maximum values.

(b) - No abnormal discoloration from unnatural causes.

(c) - The allowable temperature increase over the average ambient temperature for each month. This rise shall be based on the average of the maximum daily temperature readings recorded at the site but upstream of the mixing zone over a period of one (1) month.

(d) - Sampling taken between 9:00 AM and 4:00 PM.

(e) - Not more than 30 mg/L increase.

(f) - Applicable only to lakes or reservoirs, and similarly impounded water.

(g) - When applied to lakes or reservoirs, the Phosphate as P concentration should not exceed an average of 0.05 mg/L nor a maximum of 0.1 mg/L.

(h) - These values refer to the geometric mean of the most probable number of coliform organism during a 3-month period and that the limit indicated shall not be exceeded in 20 percent of the samples taken during the same period.

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