Water Quality Report WATER QUALITY REPORTof the OF THE SEVEN CRATER LAKES 2006-2008
SSeevveenn CCrraatteerr llaakkeess Prepared by:
Imelda R. Zapanta – Chemist II Michael Salandanan – Biologist I Marilou G. Directo – Senior Environmental Management Specialist Usman Datu Mamadra Jr. – Laboratory Technologist II Jonathan U. Nicolas – Aquaculturist II Archilles R. de la Cruz – Data Encoder
Reviewed by :
Jocelyn G. Sta. Ana – OIC, Environmental Quality and Research Div. Adelina C. Santos-Borja – OIC, Environmental Regulations Department Jacqueline N. Davo – Licensing officer III
For more information, please contact
Environmental Quality Management Division (EQMD) Laguna Lake Development Authority Km. 24 Manila East Road Club Manila East Compound Taytay, Rizal
LAGUNA LAKE DEVELOPMENT AUTHORITY Environmental Quality and Research Division WATER QUALITY REPORT OF THE SEVEN CRATER LAKES 2006-2008
Prepared by:
Imelda R. Zapanta – Chemist II Michael Salandanan – Biologist I Marilou G. Directo – Senior Environmental Management Specialist Usman Datu Mamadra Jr. – Laboratory Technologist II Jonathan U. Nicolas – Aquaculturist II Archilles R. de la Cruz – Data Encoder
Reviewed by :
Jocelyn G. Sta. Ana – OIC, Environmental Quality and Research Div. Adelina C. Santos-Borja – OIC, Environmental Regulations Department Jacqueline N. Davo – Licensing officer III
For more information, please contact
Environmental Quality Management Division (EQMD) Laguna Lake Development Authority Km. 24 Manila East Road Club Manila East Compound Taytay, Rizal
Tel. No. 286-61-43 Fax No. 286-61-43
Email Address: [email protected]
TABLE OF CONTENTS
Page
INTRODUCTION …………………………………………………………………………. 1
METHODOLOGY ……………………………….………………………………………… 3
WATER QUALITY EVALUATION…….…………………………………………………. 4
pH…………………………………………………………………………………………. 4
Dissolved Oxygen (DO)….…………………………………………………………….. 4
Biochemical Oxygen Demand (BOD)…………………………………………………. 10
Ammonia (NH3-N)…………. …………………………………………………………… 11
Nitrate (NO3-N)………………………………………………………………………….. 12
Phosphate (PO4-P)……………………………………………………………………… 13
Chloride…………………………………………………………………………………… 14
Turbidity…………………………… ……………………………………………………. 15
Total Dissolved Solids (TDS) ….……………………………………………………... 16
Total Suspended Solids (TSS)…………………………………………………………. 17
Total Coliform/Fecal Coliform …………………………………………………………. 18
Chlorophyll-a…………………..…………………………………………………………. 20
Phytoplanktons….……………………………………………………………………… 21
Zooplanktons…………………………………………………………………………… 23
RECOMMENDATIONS………………………..………………………………………… 25
LIST OF FIGURES
Page
FIGURE 1. Seven Crater Lakes…………. …………………..………………………... 2
FIGURE 2. pH Level in the Seven Crater Lakes………………..…………………….. 4
FIGURE 3. Dissolved Oxygen Level in the Seven Crater Lakes…..………….……… 5
FIGURE 4. Dissolved Oxygen Profile in Bunot Lake….…………….………………... 6
FIGURE 5. Dissolved Oxygen Profile in Calibato Lake……….………………………. 6
FIGURE 6. Dissolved Oxygen Profile in Mohicap Lake ..…………………………….. 7
FIGURE 7. Dissolved Oxygen Profile in Palakpakin Lake………..…………………… 7
FIGURE 8. Dissolved Oxygen Profile in Sampaloc Lake……..………………………. 8
FIGURE 9. Dissolved Oxygen Profile in Pandin Lake………….…………………….. 8
FIGURE 10. Dissolved Oxygen Profile in Yambo Lake………..……………………… 9
FIGURE 11. Biochemical Oxygen Demand Level in the Seven Crater Lakes ....….. 10
FIGURE 12.Ammonia Level in the Seven Crater Lakes .…………………………….. 11
FIGURE 13.Nitrate Level in the Seven Crater Lakes ………………………………… 12
FIGURE 14. Phosphate Level in the Seven Crater Lakes………….………………… 13
FIGURE 15. Chloride Level in the Seven Crater Lakes….………….………………… 14
FIGURE 16. Turbidity Level in the Seven Crater Lakes’’’’.………….………………… 15
FIGURE 17. Total Dissolved Solids Level in the Seven Crater Lakes.……………… 16
FIGURE 18. Total Suspended Solids Level in the Seven Crater Lakes.…………… 17
FIGURE 19. Total Coliform Counts in the Seven Crater Lakes…….………………… 18
FIGURE 20. Fecal Coliform Counts in the Seven Crater Lakes….………………… 19
FIGURE 21. Chlorophyll-a Level in the Seven Crater Lakes..…….………………… 20
FIGURE 22. Total Phytoplankton Counts in the Seven Crater Lakes.…………… 21
FIGURE 23. Total Zooplankton Counts in the Seven Crater Lakes.………………… 24
LIST OF TABLES
Page
TABLE 1. Characteristics of the Seven Crater Lakes ………………………….. 1
TABLE 2. Phytoplankton Counts by Group………………………………….…… 21-22
TABLE 3. Zooplankton Counts by Group …………………………………..……. 23
Water Quality Report of the Seven Crater Lakes 2006-2008
WATER QUALITY REPORT OF THE SEVEN CRATER LAKES
I.Introduction
San Pablo City is a chartered city in the Province of Laguna. It is approximately 70 kilometers away from Metropolitan Manila. It is famous for its Seven Crater Lakes, also known as Maar Lakes namely: Bunot Lake, Calibato Lake, Mohicap Lake, Palakpakin Lake, Pandin Lake, Sampaloc Lake and Yambo Lake. Its catchment area is Mt. San Cristobal with an area of 27.5 square kilometers.
Lake Elevation Water Area (m,asl ) (hectares) Depth (m)
Bunot 110± 23.0 30.5
( Brgy Concepcion SPC)
Calibato 170± 156.0 43.0
(Brgy Sto. Angel SPC,Brgy Tala & Brgy Antipolo Rizal Laguna )
Mohicap 80± 30.40 22.89
( Brgy. San Buenaventura SPC )
Palakpakin 100± 7.7 47.98
(Brgy.Dolorez,San Lorenzo,San Buenaventura SPC )
Pandin 160± 61.75 24
(Brgy Sto. Angel SPC )
Sampaloc 106 27.60 104.0
( Brgy Concepcion, IV-A,V-A, San Lucas I SPC)
Yambo 160± 38 30.5
(Brgy San Lorenzo SPC,Brgy Sulsugin Nagcarlan Laguna )
Table 1: Characteristics of the Seven Crater Lakes
The Seven Freshwater Lakes of San Pablo City were formed by a unique process called phreatic eruption where shallow lava from Mt. San Cristobal intersected groundwater which blew out (steam-heated eruption) the overlying rocks to form a circular and crater-like depression that eventually filled up with
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Water Quality Report of the Seven Crater Lakes 2006-2008
rainwater. The varying depths of these lakes which are from 7 meters to 156 meters suggest a volcanic origin. (Ramon B. San Andres – FSLF, Inc.)
Sampaloc Lake is the largest among San Pablo’s Seven Crater Lakes. It is considered one of the prime tourist spots in the city. It abounds with tilapia, big head carp and several species of freshwater fish like ayungin, dalag and hito including shrimps.
Calibato Lake is the deepest of all the seven lakes with an average depth of 156 meters. It has the greatest volume of water in storage which is approximately 29,600 cubic meters. Calibato Lake supplies the city and nearby towns with abundant fish.
Pandin Lake and Yambo Lake are known as “ The Twin Lakes “.Both lakes are considered oligotropic because of their deep clear lakes with low nutrient supplies, high dissolved oxygen level and containing little organic matter. Pandin Lake is San Pablo’s best kept lake.
Mohicap Lake is also a major source of tilapia for Metro Manila and suburbs.
Palakpakin Lake, the shallowest among the seven lakes, is utilized as communal fishing ground. An increasing construction of fishcages resulted to limited open fishing ground for the fisherfolks.
Bunot Lake is used primarily for floating cages operation where most of the resident derived their source of income.
Fig. 1 – Seven Crater Lakes
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II. METHODOLOGY
The monitoring and sampling of the Seven Crater Lakes is conducted every month in the 1st and 4th quarters of the year and every 3rd month of the 2nd and 3rd quarters of the year.
Parameters monitored include:
Physico-Chemical parameters:
pH Dissolved Oxygen at different depth Biochemical Oxygen Demand Ammonia Nitrate, Phosphate Total Dissolved Solids Total Suspended Solids Chloride Turbidity
Biological parameters:
Phytoplankton Zooplankton Chlorophyll-a
Bacteriological parameters:
Total Coliforms Fecal Coliforms
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III. WATER QUALITY EVALUATION
Monitoring data are evaluated based on the Class C Water Quality Criteria under the Department of Environment and NaturaL Resources (DENR) Administrative Order #34 Series of 1990.
1. pH
The term “pH” was originally derived from the French term “pouvoir hydrogene”; in English, this means “hydrogen power.” pH is a measure of the acidity or alkalinity of water. It is usually measured by a colorimetric test - litmus paper which changes color with increased acidity or alkalinity or by electrometric method - pH meter. The pH scale ranges from 0 to 14. If the water is acidic, the pH is 0 to 6.9; neutral is 7.0; alkaline is 7.1 to 14. A pH range of 6.5 to 8 is optimal for freshwater.
All the Maar lake stations conformed to the pH criterion of 6.5 to 8.5 units for the period 2006 to 2008.
2006 pH 2007
2008
9 C las s C C riterion 8 7 C las s C C riterion u 6 n 5 i 4 t 3 s 2 1 0
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 2. ph Level in the Seven Crater Lakes
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2. DISSOLVED OXYGEN ( DO )
Dissolved Oxygen is a very important indicator of a water body’s ability to support aquatic life. It is found in microscopic bubbles of oxygen that are mixed in the water and occurs between water molecules. Oxygen enters the water by absorption directly from the atmosphere or by aquatic plant and algae photosynthesis. Oxygen is removed from the water by respiration and decomposition of organic matter. The colder the water, the more oxygen can be dissolved in water. In general, as water temperature increases, dissolved oxygen decreases. Freshwater lakes, streams, and tap water generally contain much less salt, so dissolved oxygen are higher.
The annual mean DO concentration ranges from 4.1 mg/L (Lake Mohicap, 2006) to 7.3 mg/L (Lake Pandin, 2006). Lake Palakpakin, Pandin,and Yambo, consistently passed the DO criterion for Class “C” water set at 5 mg/L from 2006 to 2008 while Lake Calibato consistently failed the DO criterion. Both Bunot and Mohicap Lakes passed the criterion in 2006 but failed in 2007 and 2008., whereas Lake Sampaloc failed only in 2006 .
Dissolved Oxygen 2006 2007
2008
8 C las s C 7 C riterion m 6 g 5 / 4 L 3 2 1 0
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 3. Dissolved Oxygen Level in the Seven Crater Lakes
Annual mean DO at different depths
Dissolved oxygen was measured at various depths in the Crater lakes: surface, 2, 4, 6, 10, 15, 20, 25, 30, and 35 meters.
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For Bunot, Mohicap and Calibato lakes, the DO compliance to the set criterion of 5 mg/L was up to 2 meters only.
DO , Bunot ( mg/L )
12
10 2006
m 8 2007 g 2008 / 6 L 4 C las s C C riterion 2
0 S 2 4 6 10 15 20 25 Depth , m
Figure 4. Dissolved Oxygen Profile in Bunot Lake
DO , Calibato ( mg/L )
12 10 m 2006 8 g / 6 2007 L 4 2008 2 C las s C 0 C riterion S 2 4 6 10 15 20 25 30 35 Depth , m.
Figure 5. Dissolved Oxygen Profile in Calibato Lake
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DO , Mohicap ( mg/L )
12 10 2006 m 8 g 2007 / 6 2008 L 4 C las s C 2 C riterion 0 S 2 4 6 10 15 20 25 Depth , m.
Figure 6. Dissolved Oxygen Profile in Mohicap Lake
Palakpakin and Samplaloc Lakes showed slight improvement in the water quality in terms of dissolved oxygen. In Palakpakin, the desirable DO was attained up to 2 meters in 2006 and 2007 and increased up to 4 meters in 2008. In the same manner, Sampaloc Lake attained a DO >5 mg/L up to 4 meters in 2006 and increased to 6 meters in 2007 and 2008.
DO , Palakpakin , ( mg/L )
10 9 8 2006 m 7 g 6 2007 / 5 2008 L 4 3 C las s C 2 C riterion 1 0 S 2 4 6 Depth , m.
Figure 7. Dissolved Oxygen Profile in Palakpakin Lake
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DO, Sampaloc (mg/L)
9 8 2006 7 m 6 2007 g 5 2008 / 4 L 3 C las s C 2 C riterion 1 0 S 2 4 6 10 15 20 25
Figure 8. Dissolved Oxygen Profile in Sampaloc Lake
Pandin and Yambo Lakes consistently complied with the DO criterion up to 25 meters.
DO , Pandin ( mg/L )
9 8 7 m 6 2006 g 5 / 2007 4 L 3 2008 2 C las s C 1 C riterion 0 S 2 4 6 10 15 20 25 Depth , m.
Figure 9. Dissolved Oxygen Profile in Pandin Lake
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DO , Yambo ( mg/L )
9 8 7 m 6 2006 g 5 / 2007 4 L 3 2008 2 C las s C 1 C riterion 0 S 2 4 6 10 15 20 25 Depth , m.
Figure 10. Dissolved Oxygen Profile in Yambo Lake
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3. BIOCHEMICAL OXYGEN DEMAND ( BOD )
BOD is a measure of how much oxygen is used by microorganism in the aerobic oxidation, or breakdown of organic matter in the streams. Usually, the higher the amount of organic matter found in the stream, the more oxygen is used for aerobic oxidation. The higher the BOD, the more polluted the water.
BOD mg / L 5 , 2006
2007 12 2008 10 m 8 C lass C g C riterion / 6 L 4 2 0
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 11. Biochemical Oxygen Demand Levels in the Seven Crater Lakes
Bunot Lake consistently failed in the Class “C” water criterion of 7 mg/L for BOD while Palakpakin, Pandin, and Yambo Lakes showed consistent compliance in the BOD criterion. Sampaloc, Calibato and Mohicap Lakes showed improvement as evidenced by the decrease in BOD concentrations.
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4. NUTRIENTS
4.1 AMMONIA (NH3-N)
Pure ammonia is strong smelling, colorless gas. In nature, ammonia is formed by the action of bacteria on protein and urea. Ammonia is toxic to fish and aquatic organisms, even in very low concentration
There is no Philippine criterion for ammonia at the moment. Instead, the monitored data was compared with the criterion set by the Environmental Study Board, 1973.
Pandin, Palakpakin, and Yambo Lakes consistently conformed with the criterion of 0.2 mg/L (Environmental Study Board, 1973). On the other hand, Bunot, Calibato, Mohicap, and Sampaloc Lakes consistently failed the criteria for ammonia (2006-2008). The ammonia concentration ranges from 0.0163 mg/L (Yambo, 2008) to 4.9406 mg/L (Bunot, 2007).
Ammonia , mg/L
6 m 5 2006 g 4 / 3 2007 L 2 1 2008 0 ESB C riterion
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 12. Ammonia Levels in the Seven Crater Lakes
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4.2 NITRATE (NO3-N)
Nitrogen in water is naturally derived from the atmosphere in gaseous form. In water, it is converted to fixed forms by biological or chemical processes. Nitrate is found in sewage discharge, fertilizer run-off, and leakage from septic system.
For 2006-2008, all the Crater Lakes conformed with the Class “C” criterion of 10 mg/L for nitrate. The nitrate concentration ranges from 0.0103 mg/L (Pandin, 2006) to 0.1709 mg/L (Sampaloc, 2008).
Nitrate , mg/L
0.18 0.16 0.14 m 0.12 g 0.1 2006 / 0.08 2007 L 0.06 0.04 2008 0.02 0
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 13. Nitrate Levels in the Seven Crater Lakes
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4.3 PHOSPHATE (PO4)
Phosphate is found in fertilizer and some detergents. Phosphorus is necessary for plant and animal growth. Too much production of these nutrients leads to eutrophication.
For Class”C” waters, the allowable phosphate concentration is set at 0.4 mg/L. When applied to lakes and reservoir, the phosphate concentration should not exceed an average of 0.05 mg/L nor a maximum of 0.1 mg/L.
The annual mean phosphate concentration ranges from 0.0162 mg/L (Yambo, 2006) to 1.8585 mg/L (Bunot, 2006). Only Pandin and Yambo Lakes consistently conformed with the Class “C” water criterion of 0.05 mg/L for phosphate while the rest failed. Lake Bunot registers the highest concentration of phosphate.
Phosphate , mg/L
2 1.8 1.6 m 1.4 2006 g 1.2 / 1 2007 L 0.8 0.6 2008 0.4 0.2 C las s C 0 C riterion
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 14. Phosphate Levels in the Seven Crater Lakes
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5. CHLORIDE
Chloride anions are usually present in natural waters. A high concentration of chloride is evident in water that is in contact with rock formation. It can also be an indication of sewage and industrial pollution or by an intrusion of salt water into a fresh water body. A high chloride content has a corrosive effect on metal pipes and structure and is harmful to most trees and plants.
All the Crater Lakes conformed with the Class”C” water criterion of 350 mg/L for chloride. The annual mean chloride concentration range from 10 mg/L (Yambo, 2006) to 29 mg/L (Pandin, 2007).
Chloride , mg/L
2006 400 350 2007 m300 g250 2008 200/ 150 L100 C las s C 50 0 C riterion
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 15. Chloride Levels in the Seven Crater Lakes
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6. TURBIDITY
Turbidity is a measure of the amount of particulate matter that is suspended in water. Water that has high turbidity appears cloudy or opaque. The most frequent causes of turbidity in lakes and rivers are plankton and soil erosion from logging, mining, and dredging operation. Fish cannot see very well in turbid water and may have difficulty finding food. On the other hand, turbid water may make it easier for fish to hide from predators. Turbidity is measured in NTU (Nephelometric Turbidity Unit).
The annual mean turbidity range from 1 NTU (Palakpakin, 2006 and 2008) to 28 mg/L (Bunot, 2006). Lake Bunot exhibits the highest turbidity reading (2006- 2008). At present there is no established criterion for turbidity.
Turbidity , NTU
30 25
N 20 2006 T 15 U 2007 10 2008 5 0
BUNOT PANDIN YAMBO CALIBATO MOHICAP SAMPALOC PALAKPAKIN
Figure 16. Turbidity Levels in the Seven Crater Lakes
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7. TOTAL DISSOLVED SOLIDS (TDS)
Total Dissolved Solids are solids in water that can pass through a filter. These maybe anions and cations, such as carbonate, bicarbonate, calcium, magnesium, which are necessary for aquatic life. High TDS concentrations can produce laxative effect and can give unpleasant mineral taste to water.
Total Dissolved Solids
300 250 200 2006
150 2007 mg/L 100 2008 50 0
BUNOT PANDIN YAMBO MOHICAP CALIBATO SAMPALOC PALAKPAKIN
Figure 17. Total Dissolved Solids Levels in the Seven Crater Lakes
The annual mean Total Dissolved Solids ranges from 89 mg/L (Yambo, 2008) to 243 mg/L (Mohicap, 2007). No criterion was set for TDS. The results of annual mean TDS are relatively close to each other.
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8. TOTAL SUSPENDED SOLIDS (TSS)
Total Suspended Solids are solids in water that can be trapped by a filter. TSS can include silt, decaying plants, animal matter, industrial waste and sewage. High concentration of suspended solids can cause many problems for stream health and aquatic life.
The annual mean TSS ranges from 1 mg/L (Pandin,2007-2008) to 41 mg/L (Bunot,2006) Lake Bunot showed decreasing trend from 2006 to 2008. There is no mark difference in the annual mean TSS for the other lakes..
Total Suspended Solids
45 40 35 30 2006 25
20 2007 mg/L 15 2008 10 5 0
BUNOT PANDIN YAMBO MOHICAP CALIBATO SAMPALOC PALAKPAKIN
Figure 18. Total Suspended Solids Levels in the Seven Crater Lakes
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Water Quality Report of the Seven Crater Lakes 2006-2008
9. TOTAL COLIFORM/ FECAL COLIFORM
The coliform group is used as an indicator of the sanitary quality of the water because its presence in the water body would suggest fecal contamination or would indicate the disease-producing potential of the water. Ideally, water should not contain any microorganisms known to be pathogenic or any bacteria indicative of fecal pollution. In order to estimate the probability of the pathogens being contributed from human feces as well as from animal droppings, the total coliform and fecal coliform must be quantified. High counts of coliform bacteria will render the water unsuitable for domestic water supply, fishery, agricultural, recreational and some industrial uses.
The annual geomean of total coliform of 6361 MPN/100 ml at Bunot Lake in 2006 exceeded the Water Quality Criterion for Class C of 5000 MPN/100 ml. However, the annual total coliform geomean of 812 MPN/100 ml in 2007 and 963 MPN/100 ml in 2008 both met the Water Quality Criterion for total coliform of 5000 MPN/100 ml. The other Crater Lakes like Yambo, Calibato, Palakpakin, Sampaloc and Mohicap met the Water Quality Criterion for Class C of 5000 MPN/100 ml for 2006, 2007 and 2008.
Total Coliform
6000 Class C Criterion 5000 5000 MPN/100 4000 2006 Year
MPN 3000 2000 2007 1000
0 Bunot Calibat o Mohicap Palakpakin Pandin Sampaloc Yambo 2008 Crater Lakes
Figure 19. Total Coliform Counts in the Seven Crater Lakes
During the study period the annual geomean of fecal coliform was highest at Bunot Lake recorded at 1603 MPN/100 ml, 399 MPN/100 ml and 660 MPN/100 ml in 2006, 2007 and 2008, respectively. This was followed by Yambo with a total annual geomean for 3 years (2006-2008) of 1404 MPN/100 ml. Palakpakin was third with a fecal coliform annual geomean measured at 1062 MPN/100 ml, followed by Calibato with 976 MPN/100 ml, Mohicap with 893 MPN/100 ml and Sampaloc with 543 MPN/100 ml. The least in terms of fecal coliform concentration was measured at Pandin with 498 MPN/100 ml.
Bunot Lake gave the highest annual geomean of total and fecal coliform during the three (3) year study period as compared with the Other Crater Lakes which in
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effect indicated the increasing aquaculture and human activities. Urban development is often reported as a factor that could affect bacterial count in lakes because human and domestic animal wastes, are potential sources of contamination and can increase with present urban development.
Fecal Coliform
1600
1400 1200 2006Year 1000
800 MPN 2007 600
400 200 2008 0 Bunot Calibato M ohicap Palakpakin Pandin Sampaloc Yambo Crater Lakes
Figure 20. Fecal Coliform Counts in the Seven Crater Lakes
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10. CHLOROPHYLL –a
Chlorophyll-a is an indicator of phytoplankton standing biomass in the water body.
The cholorophyll –a annual averages for Calibato, Palakpakin Pandin and Mohicap Lakes were increasing in trend, while Sampaloc Lake, Bunot Lake and Yambo Lake showed fluctuations in the concentrations. The highest annual chlorophyll-a reading was measured at 150.63 ug/L in Bunot Lake in 2008 and the lowest annual average reading was 12.3 ug/L recorded at Lake Pandin in 2006. Bunot Lake registered the highest concentration in three (3) years with an average of 124.26 ug/L, while Pandin Lake got the lowest average during the three-year period measured at 24.96 ug/L.
The high transparency measurements could have affected the high Chlorophyll-a concentration particularly in Calibato, Palakpakin, Pandin and Mohicap Lakes.
Chlorophyll-a
160 140 120 2006 100 80 2007 ug/L 60 2008 40 20 0
Bunot Pandin Yambo Calibato Mohicap Palakpakin Sampaloc
Figure 21. Chlorophyll-a Levels in the Seven Crater Lakes
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11. PHYTOPLANKTONS
Phytoplankton, also known as algae, is a microscopic aquatic plant commonly found in lakes and other bodies of water. It plays a vital role in aquatic productivity because it occupies the first link in the food chain for being the primary producer. Phytoplankton serves as food for the zooplankton, fish, benthic fauna and other aquatic organisms. Its abundance is mainly dependent upon the light intensity, turbidity, and nutrients availability among other factors.
Calibato was the most diversified among the crater lakes with a total of 36 genera identified. It is followed by Bunot with 32 genera and Palakpakin with 30 genera. Sampaloc and Yambo are the least diversified with 26 genera.
The algal composition in the seven crater lakes belong to four (4) divisions, namely, Cyanophyta (bluegreen), Chlorophyta (green), Bacillariophyta (diatom) and Pyrrophyta (dinoflagellates).
The phytoplankton counts by group for the crater lakes are presented in the next table.
Bluegreen Green Diatoms Dinoflagellates Total Bunot 2006 154322 28901 9385 1807 194415 2007 47113 18168 9084 269 74634 2008 58922 83525 29647 2227 174321 Calibato 2006 5985 13127 14076 155 33343 2007 3991 13265 5746 134 23136 2008 218791 27504 78369 3827 328491 Mohicap 2006 5893 15567 9265 186 30911 2007 78850 17867 11218 282 108217 2008 304230 14524 37617 4593 360964 Palkpakin 2006 99690 5194 164933 1563 271380 2007 4610 3442 12892 1294 22238 2008 41671 23327 146737 5400 217135 Pandin 2006 2494 16380 3523 76 22473 2007 8617 498 831 159 10105 2008 60540 3558 20265 1276 85639 Sampaloc 2006 15567 7946 10734 27 34274 2007 53815 1532 9358 10 64715 2008 281583 42233 101836 380 426032
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Yambo 2006 316 4712 1991 33 7052 2007 29388 4065 38465 3666 75584 2008 89643 27653 56022 1220 174538
Table 2. Phytoplankton Counts by Group
Microcystis sp., a blue green algae, was the dominant species in almost all of the lakes for the period 2006 to 2008.
Green algae became dominant in Bunot in 2008, in Calibato in 2007, in Mohicap, Yambo and Pandin in 2006.
Diatoms such as Melosira sp. and Stephanodiscus sp., consistently dominated the algal population in Palakpakin Lake for three years. Diatoms also was the dominant groupin Calibato in 2006 and in Yambo in 2007.
Dinoflagellates remained low in number.
The annual total phytoplankton counts for the seven lakes are presented in Figure 22. 2008 registered the highest total counts for Calibato, Sampaloc, Pandin, Mohicap and Yambo. For Bunot and Palakpakin, the highest counts were registered in 2006.
Total Phytoplankton Counts
450000 400000 350000 300000 2006 250000 2007 200000 150000 2008 Counts/mL 100000 50000 0
Bunot Pandin Yambo Calibato Mohicap Palakpakin Sampaloc
Figure 22. Total Phytoplankton Counts in the Seven Crater Lakes
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12. ZOOPLANKTONS
Zooplankton occupies the consumer level in the food chain. These consumers utilized the phytoplankton as food. The zooplankton identified belonged to three (3) major groups namely: Rotifera, Cladocera, and Copepoda.
Copepoda was the dominant species in Bunot, Palakpakin, Pandin and Yambo throughout the three year period. It was also dominant in Calibato and Samplaloc in 2006 and 2008, and in Mohicap in 2006 and 2007.
Rotifera dominated the zooplankton counts in Calibato and Samplaoc in 2007, in Mohicap in 2008.Cladocera remained consistently low in number.
Rotifer Cladoceran Copepod Total Bunot 2006 14 8 94 116 2007 13 4 29 46 2008 89 12 136 237 Calibato 2006 6 4 20 30 2007 14 2 13 29 2008 99 23 168 290 Mohicap 2006 5 5 38 48 2007 3 3 22 28 2008 233 10 130 373 Palakpakin 2006 4 3 29 36 2007 6 3 30 39 2008 29 13 58 100 Pandin 2006 5 2 87 94 2007 7 11 41 59 2008 38 21 97 156 Sampaloc 2006 3 5 64 72 2007 53 2 18 73 2008 73 28 187 288 Yambo 2006 0 0 6 6 2007 3 4 24 31 2008 7 7 42 56 Table 3. Zooplankton Counts by Group
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The total zooplankton counts for the seven crater lakes are shown in the Figure 23. There was a significant increase in the zooplankton population in all the lakes in 2008.
Total Zooplankton Counts
400 350 300 250 2006 200 2007 150 2008 Counts/mL 100 50 0
Bunot Pandin Yambo Calibato Mohicap Palakpakin Sampaloc
Figure 23. Total Zooplankton Counts in the Seven Crater Lakes
Environmental Quality and Research Division Laguna Lake Development Authority 24
Water Quality Report of the Seven Crater Lakes 2006-2008
IV. RECOMMENDATIONS
The Seven Crater Lakes are extremely threatened by the resulting pollution from the surrounding areas (domestic wastes pollution and solid wastes), by illegal fishpens, crowded fishpens and overfeeding using artificial feeds.
The case of Samplaoc lake is a good example of rehabilitation measures being done in San Pablo. A number of settlers in the area had been relocated, hence the discharge of untreated domestic wastes had been reduced. As a result, the Biochemical Oxygen Demand (BOD) and the Dissolved Oxygen has improved.
In order to arrest further degradation of the lakes, it is recommended that the following be implemented and sustained:
Zoning and Management / Development Plan Compliance to 10 % aquaculture area as provided by RA 8550 ( Fishery Code ) Appropriate feeding practices in the aquaculture structures Adequate treatment of wastes before discharge into the lake No introduction of invasive species such as jaguar guapote and red pacu.
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Environmental Quality and Research Division Laguna Lake Development Authority 25