Seven Lakes of San Pablo, Laguna Province
Encyclopedia
The Seven Lakes of San Pablo are seven crater lake
s scattered around the City of San Pablo
, in the province
of Laguna, Philippines
.
s or low-profile volcanic crater
s located in the San Pablo Volcanic Field
. They are among the 200 small monogenetic volcano
es found along the Macolod Corridor, a rift zone
between Mount Makiling
and Mount Banahaw
, which is part of the larger Southwestern Luzon
Volcanic Field
,. These craters are formed by phreatomagmatic eruptions, an eruption where ground water comes in contact with hot magma
pushing up near the Earth's surface.
study on the lakes and adjoining rivers in San Pablo, sulfate
concentrations were considerably higher than the naturally occurring sulfates from volcanism. Samples were taken from other areas underlain with similar volcanic rocks from the old eruptions (e.g. Taal volcano
) like Indang
, in the province of Cavite
and the La Mesa Watershed, the water supply reservoir
for Metropolitan Manila. The analyses indicated that the elevated level of sulfates were not related to volcanism but anthropogenic
or man-made, and among the causes are sewage
, fertilizers, herbicides, pesticides etc.
, illegal fish pens, commercial and business infrastructures on the shores have proliferated on some of the lakes causing increased pollution. Overuse of commercial fish feeds have resulted in high nitrogen levels and low dissolved oxygen that has led to fish kill
s in the early and late 1990s. In January 2004, fish kills were observed in six of the seven lakes. Various ecological conservation efforts by both government and non-government organizations, like the Friends of the Seven Lakes Foundation, had been implemented in recent years. One of these is the demolition of human-made structures along the lakes' shoreline.
Crater lake
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...
s scattered around the City of San Pablo
San Pablo, Laguna
The City of San Pablo , a first class city in the province of Laguna, Philippines, is one of the country's oldest cities. The City of San Pablo lies in the southern portion of Laguna province...
, in the province
Provinces of the Philippines
The Provinces of the Philippines are the primary political and administrative divisions of the Philippines. There are 80 provinces at present, further subdivided into component cities and municipalities. The National Capital Region, as well as independent cities, are autonomous from any provincial...
of Laguna, Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
.
The Lakes
The seven lakes of the city are:- Lake BunotLake BunotLake Bunot is one of the Seven Lakes of San Pablo, Laguna. It is located in Brgy. Concepcion, San Pablo City. Only 4.5 km from the city proper, Bunot is known for its cultured tilapia and fishpens for Nilotica fingerlings. Bunot has a normal surface area of 30.5 hectares with a maximum depth of 23...
- Lake CalibatoLake CalibatoLake Calibato is one of the 7 crater lakes collectively called "Pitong Lawa" or Seven Lakes of San Pablo in Laguna. The lake is situated in Brgy. Sto. Angel in San Pablo City. Calibato has an area of 42 hectares and maximum depth of 135 meters. Calibato's greatest volume of water in storage is...
, sometimes spelled as Lake Kalibato - The twin lakes of Yambo and PandinLakes Pandin and YamboPandin and Yambo are twin crater lakes separated by a narrow strip of land. They are part of the Seven Lakes system in San Pablo. The lakes can be found in Brgy. San Lorenzo, San Pablo City, Laguna, Philippines....
- Lake PalakpakinLake PalakpakinLake Palakpakin is part of the Seven Lakes of San Pablo system in Laguna, Philippines. Palakpakin is located in Brgy. San Buenaventura, San Pablo City is similar to Sampalok Lake...
, sometimes spelled as Lake Palacpaquin or Palacpaquen - Lake MuhikapLake MuhikapLake Muhikap is one of the seven lakes of San Pablo City, in the province of Laguna, Philippines. The lake which is located in Brgy. Sta. Catalina has an area of lake, and it is one of the main suppliers of water in the city...
, also known as Lake Mojicap or Lake Mohicap - Lake SampalocLake SampalocLake Sampaloc is an inactive volcanic maar on the island of Luzon, the Philippines.It is the largest of the Seven Lakes of San Pablo, Laguna. Nearly half of the lake's depth has a shallow depression at the lake's bottom, indicating its volcanic origin...
, also spelled as Lake Sampalok, the largest of the seven lakes
Geology
The lakes are maarMaar
A maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma. A maar characteristically fills with water to form a relatively shallow crater lake. The name comes from the local Moselle...
s or low-profile volcanic crater
Volcanic crater
A volcanic crater is a circular depression in the ground caused by volcanic activity. It is typically a basin, circular in form within which occurs a vent from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth...
s located in the San Pablo Volcanic Field
San Pablo Volcanic Field
-Identity:The Smithsonian Institution's Global Volcanism Program lists the San Pablo volcanic field as a recently active volcanic field with numerous geothermal areas within it....
. They are among the 200 small monogenetic volcano
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
es found along the Macolod Corridor, a rift zone
Rift zone
A rift zone is a feature of some volcanoes, especially the shield volcanoes of Hawaii, in which a linear series of fissures in the volcanic edifice allows lava to be erupted from the volcano's flank instead of from its summit...
between Mount Makiling
Mount Makiling
Mount Makiling, also rarely Mount Maquiling, is a potentially active volcano in Laguna province on the island of Luzon, Philippines. It rises to 1,090 m above mean sea level.-Legend:...
and Mount Banahaw
Mount Banahaw
Mount Banahaw is an active volcano on Luzon Island in the Republic of the Philippines. The three-peaked volcano complex is located between the provinces of Laguna and Quezon and is the tallest mountain in the CALABARZON region dominating the landscape for miles around.The mountain is considered by...
, which is part of the larger Southwestern Luzon
Luzon
Luzon is the largest island in the Philippines. It is located in the northernmost region of the archipelago, and is also the name for one of the three primary island groups in the country centered on the Island of Luzon...
Volcanic Field
Volcanic field
A volcanic field is an area of the Earth's crust that is prone to localized volcanic activity. They usually contain 10 to 100 volcanoes, such as cinder cones and are usually in clusters. Lava flows may also occur...
,. These craters are formed by phreatomagmatic eruptions, an eruption where ground water comes in contact with hot magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
pushing up near the Earth's surface.
Petrographic Analysis
In a recent rocks and sediment analysis or petrographicPetrography
Petrography is a branch of petrology that focuses on detailed descriptions of rocks. Someone who studies petrography is called a petrographer. The mineral content and the textural relationships within the rock are described in detail. Petrographic descriptions start with the field notes at the...
study on the lakes and adjoining rivers in San Pablo, sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
concentrations were considerably higher than the naturally occurring sulfates from volcanism. Samples were taken from other areas underlain with similar volcanic rocks from the old eruptions (e.g. Taal volcano
Taal Volcano
Taal Volcano is a complex volcano located on the island of Luzon in the Philippines. Historical eruptions are concentrated on Volcano Island, an island near the middle of Lake Taal. The lake partially fills Taal Caldera, which was formed by powerful prehistoric eruptions between 140,000 to 5,380 BP...
) like Indang
Indang, Cavite
Indang is a 1st class municipality in the province of Cavite, Philippines.Although Indang is a small municipality, it is starting to be developed. Now, fast-food restaurants such as Jollibee, have been opened up .Indang has a public market, or palengke, where goods such as vegetables, seafood,...
, in the province of Cavite
Cavite
Cavite is a province of the Philippines located on the southern shores of Manila Bay in the CALABARZON region in Luzon, just 30 kilometers south of Manila. Cavite is surrounded by Laguna to the east, Metro Manila to the northeast, and Batangas to the south...
and the La Mesa Watershed, the water supply reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
for Metropolitan Manila. The analyses indicated that the elevated level of sulfates were not related to volcanism but anthropogenic
Anthropogenic
Human impact on the environment or anthropogenic impact on the environment includes impacts on biophysical environments, biodiversity and other resources. The term anthropogenic designates an effect or object resulting from human activity. The term was first used in the technical sense by Russian...
or man-made, and among the causes are sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
, fertilizers, herbicides, pesticides etc.
Hiking trails
In 2005, the Rotary Club of San Pablo City held a ceremony that officially opened the hiking trails that connect the seven lakes of the city. The Rotarians were aiming for economic, environmental and health benefits of the trails to the community.Conservation
The lakes are threatened by human intervention and exploitation, most especially Lake Sampaloc, which is located right in the center of San Pablo City. Several illegal settlementsSquatting
Squatting consists of occupying an abandoned or unoccupied space or building, usually residential, that the squatter does not own, rent or otherwise have permission to use....
, illegal fish pens, commercial and business infrastructures on the shores have proliferated on some of the lakes causing increased pollution. Overuse of commercial fish feeds have resulted in high nitrogen levels and low dissolved oxygen that has led to fish kill
Fish kill
The term fish kill, known also as fish die-off and as fish mortality, is a localized die-off of fish populations which may also be associated with more generalised mortality of aquatic life...
s in the early and late 1990s. In January 2004, fish kills were observed in six of the seven lakes. Various ecological conservation efforts by both government and non-government organizations, like the Friends of the Seven Lakes Foundation, had been implemented in recent years. One of these is the demolition of human-made structures along the lakes' shoreline.