Lake Lanao is a large ancient lake in the Philippines, located in Lanao del Sur province in the country's southern island of Mindanao. With a surface area of 340 km2, it is the largest lake in Mindanao, the second largest lake in the Philippines and counted as one of the 15 ancient lakes in the world. Scholars have been pushing for the lake's inclusion in the UNESCO World Heritage List; the lake was formed by the tectonic-volcanic damming of a basin between two mountain ranges and the collapse of a large volcano. It has a maximum depth of 122 m, a mean depth of 60.3 m. The basin gets progressively deeper towards the south; the lake is fed by four rivers. Its only outlet is the Agus River, which flows northwest into Iligan Bay via two channels, one over the Maria Cristina Falls and the other over the Tinago Falls. A hydroelectric plant installed on the Lanao Lake and Agus River system generates 70% of the electricity used by the people of Mindanao; the lake is a home of legends of the Meranaw tribe.
The name Meranaw was derived from the name of the lake and it means "the people living around the lake". Lake Lanao was proclaimed as a watershed reservation in 1992 through Presidential Proclamation 971 to ensure protection of forest cover and water yield for hydropower and domestic use; the lake is home to 18 endemic species of cyprinid fish in the genus Barbodes. It supports a large number of waterfowl. An investigations in 1992 only managed to locate three of the endemic fish species, only two were located in 2008, it is believed that overfishing and competition from introduced species caused the extinction of the remaining. In October 2006, a study from the Mindanao State University discovered massive algae contamination in Lake Lanao. Poor sewage and agricultural waste management were seen as the culprit to the contamination. However, the Department of Agriculture and the Bureau of Fisheries and Aquatic Resources stated that soil erosion from indiscriminate logging and extensive land use and farming are the problems that caused the algae contamination.
The freshwater crab Sundathelphusa wolterecki is endemic to the lake region. The 18 endemic cyprinid species of Lake Lanao: Barbodes amarus Herre Barbodes baoulan Herre ** Barbodes binotatus Valenciennes Barbodes clemensi Herre Barbodes disa Herre ** Barbodes flavifuscus Herre Barbodes katolo Herre Barbodes lanaoensis Herre Barbodes lindog Herre ** Barbodes manalak Herre ** Barbodes pachycheilus Herre Barbodes palaemophagus Herre Barbodes palata Herre ** Barbodes resimus Herre * Barbodes sirang Herre sirang. Long ago, there was a polity known as Mantapoli centered in Lake Lanao; the people of the polity increased in population due to advancements in many fields. Because of the sudden growth in population and power, the equilibrium between Sebangan and Sedpan was broken; this problem soon came to the attention of archangel Diabarail. Afterwards, Diabarail told Allah the news. Sohora, the vice of Allah, advised Diabarail to go to seven regions beneath the earth and seven regions in the sky to summon the angels.
Sohora said that when Allah establishes the barahana, they will remove Mantapoli from its location and transfer it into the center of the world. When the angels were summoned and the barahana made, Mantapoli was soon teleported into the earth's center, leaving a vast hole in its former location; the hole filled with water and turned into a deep blue-colored lake. When Diabarail saw the tides of water, he went to heaven to report to Allah, he told Allah. Hearing this, Allah commanded Diabarail to summon the four winds to blow the excess waters and establish outlets where these waters will flow to. After three trails, the winds succeeded and the Agus river was established. A Meranaw is a language of Maranao people. SarimanokSarimanok is a Meranau symbol of Meranaw people. How the Angels Built Lake Lanao
A stream is a body of water with surface water flowing within the bed and banks of a channel. The stream encompasses surface and groundwater fluxes that respond to geological, geomorphological and biotic controls. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams are called rivers. Streams are important as conduits in the water cycle, instruments in groundwater recharge, corridors for fish and wildlife migration; the biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity; the study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography. Brook A stream smaller than a creek one, fed by a spring or seep, it is small and forded. A brook is characterised by its shallowness.
Creek In North America and New Zealand, a small to medium-sized natural stream. Sometimes navigable by motor craft and may be intermittent. In parts of Maryland, New England, the UK and India, a tidal inlet in a salt marsh or mangrove swamp, or between enclosed and drained former salt marshes or swamps. In these cases, the stream is the tidal stream, the course of the seawater through the creek channel at low and high tide. River A large natural stream, which may be a waterway. Runnel the linear channel between the parallel ridges or bars on a shoreline beach or river floodplain, or between a bar and the shore. Called a swale. Tributary A contributory stream, or a stream which does not reach a static body of water such as a lake or ocean, but joins another river. Sometimes called a branch or fork. There are a number of regional names for a stream. Allt is used in Highland Scotland. Beck is used in Lincolnshire to Cumbria in areas which were once occupied by the Danes and Norwegians. Bourne or winterbourne is used in the chalk downland of southern England.
Brook. Burn is used in North East England. Gill or ghyll is seen in Surrey influenced by Old Norse; the variant "ghyll" is used in the Lake District and appears to have been an invention of William Wordsworth. Nant is used in Wales. Rivulet is a term encountered in Victorian era publications. Stream Syke is used in lowland Cumbria for a seasonal stream. Branch is used to name streams in Virginia. Creek is common throughout the United States, as well as Australia. Falls is used to name streams in Maryland, for streams/rivers which have waterfalls on them if such falls have a small vertical drop. Little Gunpowder Falls and The Jones Falls are rivers named in this manner, unique to Maryland. Kill in New York, Pennsylvania and New Jersey comes from a Dutch language word meaning "riverbed" or "water channel", can be used for the UK meaning of'creek'. Run in Ohio, Michigan, New Jersey, Virginia, or West Virginia can be the name of a stream. Run in Florida is the name given to streams coming out of small natural springs.
River is used for larger springs like the Silver Rainbow River. Stream and brook are used in Midwestern states, Mid-Atlantic states, New England. Bar A shoal that develops in a stream as sediment is deposited as the current slows or is impeded by wave action at the confluence. Bifurcation A fork into two or more streams. Channel A depression created by constant erosion. Confluence The point at which the two streams merge. If the two tributaries are of equal size, the confluence may be called a fork. Drainage basin The area of land. A large drainage basin such as the Amazon River contains many smaller drainage basins. Floodplain Lands adjacent to the stream that are subject to flooding when a stream overflows its banks. Gaging station A site along the route of a stream or river, used for reference marking or water monitoring. Headwaters The part of a stream or river proximate to its source; the word is most used in the plural where there is no single point source. Knickpoint The point on a stream's profile where a sudden change in stream gradient occurs.
Mouth The point at which the stream discharges via an estuary or delta, into a static body of water such as a lake or ocean. Pool A segment where the water is deeper and slower moving. Rapids A turbulent, fast-flowing stretch of a stream or river. Riffle A segment where the flow is shallower and more turbulent. River A large natural stream, which may be a waterway. Run A somewhat smoothly flowing segment of the stream. Source The spring, or other point of origin of a stream. Spring The point at which a stream emerges from an underground course through unconsolidated sediments or through caves. A stream can with caves, flow aboveground for part of its course, underground for part of its course. Stream bed The bottom of a stream. Stream corridor Stream, its floodplains, the transitional upland fringe Streamflow The water moving through a stream channel. Thalweg The river's longitudinal section, or the line joining the deepest point in the channel at each stage from source to mouth. Waterfall or cascade The fall of water where the stream goes over a sudden drop called a knickpoint.
The stream expends kinetic energy in "trying" to eliminate the
San Marcelino the Municipality of San Marcelino, is a 1st class municipality in the province of Zambales, Philippines. According to the 2015 census, it has a population of 33,665 people; the municipality is home to Mapanuepe Lake. The town got its name after the first Capitan Municipal; the people of this municipality during that time were fond of Saints, so they added "San" to the name Marcelino, thus making it San Marcelino. The first election was held on January 14, 1906 and Matias Apostol was the first elected President. San Marcelino was Christianized after the arrival of Father Guillermo and after his departure, the people rightfully chose San Guillermo as their town's patron saint. San Marcelino is politically subdivided into 18 barangays. The area, now known as San Marcelino was owned by Sambal-speaking peoples, but over time was purchased and became owned by Ilocano-speaking peoples. Marcelinian civilization, according to old Municipal documents, started at the peak of the beautiful Vega Hill in the heart of an idyllic and luxuriant Zambales jungle during the pre-Hispanic settlers from the Ilocos Region led by the old Corpuses, Ragadios, Raguinis and Fabunans.
With courage, hard work and perseverance, these Marcelinian forefathers harnessed the untouched wilderness of Vegal Hill and its immediate surroundings and converted the area into a pulsating and vibrant community nurtured by the abundant natural yield of what was once an untamed wildlife. Vega Hill measured 440.94 square kilometers. It used to be one of the three communities; the two others were what are now known as San Antonio. Castillejos was the hub of leadership because when the Ilocanos arrived in the area, the Tagalog-speaking native residents where organized. Adventurous and united by their common struggles, the Ilocano settlers left Vega Hill and stayed in Magaring, a place now known as Barangay Linasin; this area was, still is, part of the town. The Ilocanos decided to settle at the Poblacion. However, they refused to be integrated into the communities of the local residents, they lived according to their own tradition. They were governed by their obedience to their community elders; when the Spaniards came, a kind-hearted Spanish friar, Father Guillermo, stayed at the Poblacion with the Marcelinian forefathers.
In the succeeding years, more Spanish friars came, strengthening the stronghold of Christianity among the Ilocano settlers. The need for formalizing a political/administrative structure of the town became evident as the population increased and the socio-economic life of the town became complex. A government structure was set up under the leadership of the friars whose power, at this point in time, had become entrenched, anchored on religion; the friars appointed local or district leaders, a cabeza de barangay for every barangay among which were Consuelo and Sinnerrekan. The number of barangays has expanded to 18 since then. In the settlers' barangay of barrio, a middle-aged Teniente del Barrio, Marcelino Ora, was appointed, it was after him that the town was named, long after he was gone. "San" was arbitrarily added to the name due to the people's religiosity. Domingo Magsaysay and Antonio Rolls succeeded him; when the barangay needed to choose a patron saint, the leaders chose the priest who Christianized the town, Father Guillermo.
Ath the time the priest had left San Marcelino, Like Marcelino Ora, the title of Saint was just attachéd to his name. It was after Marcelino Ora that the town was named. In 1843, the Marcelinians filed a petition for San Marcelino's elevation to a being a Pueblo through the Teniente Primero, Antonio Ladrido Juliano. In 1846, the petition was approved; the elation over the appointment of a local leader did not last long. The Marcelinian elders became discontented over the fact that their appointed leaders turned out to be just nominal leaders; the friars still made the decision in relation to important matters. In addition, the friars became shockingly abusive. In anger, many of the leaders and pockets of townspeople joined the insurrectos - rebel groups. In the forefront where Jorge Udan, Francisco Corpus and Alipio Corpus. Relenting to the demands of majority of the people, the friars agreed to give the leaders bigger participation in running their respective districts. On March 10, 1852 San Marcelino held its first municipal election for a Teniente Absoluto.
At this point, historical records became confusing. The next account has dated January 14, 1906 when a Matias Apostol was installed as the First Elected President of San Marcelino. From on, the progressive development of San Marcelino continued under duly elected leaders. From late 1900 to March 1902, the 25th Infantry Regiment, operated in Zambales, including San Marcelino, during the Philippine-American War, with elements in San Marcelino in December 1900 and March 1902. During this period, the regiment conducted policing and judiciary functions, such as the prosecution of Elias Agpalo. In 1904, due to Act Number 945 of the Philippine Commission, San Marcelino's municipal oversight was extended to neighboring Castillejos and San Antonio; that same year, Ilokano was the primary language spoken in San Marcelino, with Tagalog being a secondary language. In 1905, in a report produced by the War Department, the area around San Marcelino were used to cultivate rice, the people were Iloc
OpenStreetMap is a collaborative project to create a free editable map of the world. Rather than the map itself, the data generated by the project is considered its primary output; the creation and growth of OSM has been motivated by restrictions on use or availability of map information across much of the world, the advent of inexpensive portable satellite navigation devices. OSM is considered a prominent example of volunteered geographic information. Created by Steve Coast in the UK in 2004, it was inspired by the success of Wikipedia and the predominance of proprietary map data in the UK and elsewhere. Since it has grown to over 2 million registered users, who can collect data using manual survey, GPS devices, aerial photography, other free sources; this crowdsourced data is made available under the Open Database License. The site is supported by the OpenStreetMap Foundation, a non-profit organisation registered in England and Wales; the data from OSM is available for use in both traditional applications, like its usage by Facebook, OsmAnd, MapQuest Open, JMP statistical software, Foursquare to replace Google Maps, more unusual roles like replacing the default data included with GPS receivers.
OpenStreetMap data has been favourably compared with proprietary datasources, although in 2009 data quality varied across the world. Steve Coast founded the project in 2004 focusing on mapping the United Kingdom. In the UK and elsewhere, government-run and tax-funded projects like the Ordnance Survey created massive datasets but failed to and distribute them; the first contribution, made in the British city of London in 2005, was thought to be a road by the Directions Mag. In April 2006, the OpenStreetMap Foundation was established to encourage the growth and distribution of free geospatial data and provide geospatial data for anybody to use and share. In December 2006, Yahoo! confirmed that OpenStreetMap could use its aerial photography as a backdrop for map production. In April 2007, Automotive Navigation Data donated a complete road data set for the Netherlands and trunk road data for India and China to the project and by July 2007, when the first OSM international The State of the Map conference was held, there were 9,000 registered users.
Sponsors of the event included Yahoo! and Multimap. In October 2007, OpenStreetMap completed the import of a US Census TIGER road dataset. In December 2007, Oxford University became the first major organisation to use OpenStreetMap data on their main website. Ways to import and export data have continued to grow – by 2008, the project developed tools to export OpenStreetMap data to power portable GPS units, replacing their existing proprietary and out-of-date maps. In March, two founders announced that they have received venture capital funding of €2.4 million for CloudMade, a commercial company that uses OpenStreetMap data. In November 2010, Bing changed their licence to allow use of their satellite imagery for making maps. In 2012, the launch of pricing for Google Maps led several prominent websites to switch from their service to OpenStreetMap and other competitors. Chief among these were Foursquare and Craigslist, which adopted OpenStreetMap, Apple, which ended a contract with Google and launched a self-built mapping platform using TomTom and OpenStreetMap data.
Map data is collected from scratch by volunteers performing systematic ground surveys using tools such as a handheld GPS unit, a notebook, digital camera, or a voice recorder. The data is entered into the OpenStreetMap database. Mapathon competition events are held by OpenStreetMap team and by non-profit organisations and local governments to map a particular area; the availability of aerial photography and other data from commercial and government sources has added important sources of data for manual editing and automated imports. Special processes are in place to avoid legal and technical problems. Editing of maps can be done using the default web browser editor called iD, an HTML5 application using D3.js and written by Mapbox, financed by the Knight Foundation. The earlier Flash-based application Potlatch is retained for intermediate-level users. JOSM and Merkaartor are more powerful desktop editing applications that are better suited for advanced users. Vespucci is the first full-featured editor for Android.
StreetComplete is a new, easy Android app launched in 2016, which allows users without any OpenStreetMap knowledge to answer simple quests for existing data in OpenStreetMap, thus contribute data. Maps.me is a mobile application offering offline maps which includes a limited OSM data editor. Go Map!! is an iOS app that lets you edit information in OpenStreetMap. Pushpin is another iOS app; the project has a geographically diverse user-base, due to emphasis of local knowledge and ground truth in the process of data collection. Many early contributors were cyclists who survey with and for bicyclists, charting cycleroutes and navigable trails. Others are GIS professionals. Contributors are predominately men, with only 3–5% being women. By August 2008, shortly after the second The State of the Map conference was held, there were over 50,000 registered contributors. In April 2012, OpenStreetMap cleared 600,000 registered contributors. On 6 January 2013, OpenStreetMap reached 1 million registered users.
Around 30% of users have contributed at least one point to the OpenStreetMap database. Ground surveys are performed on foot, bicycle, or in a car, motorcycle or boat. Map data are
Lake Buhi is a lake found in Buhi, Camarines Sur in the Philippines. It has an average depth of 8 metres; the lake lies in the valley formed by Mount Iriga and Mount Malinao. It was created in 1641; the resulting landslide created a natural dam. Another theory suggests that it was created by the eruption of Mt. Asog, now dormant; the lake is famous since it is one of the few bodies of water that contains the sinarapan, the world's smallest commercially harvested fish. Aside from the sinarapan, Lake Buhi is home for other marine organisms such as the Irin-irin, Puyo, Kotnag and native catfish. Other fishes are introduced to boost the fishery industry such as the Nile tilapia, Mozambique tilapia, common carp and Bangkok hito; the forest surrounding the lake is the home of at least 25 bird species. The five endemic species are the Philippine pygmy woodpecker, Philippine hanging parrot, black-naped monarch, elegant tit and the white-eared brown dove. Other fauna found in the forest are flying lizards, monitor lizards, civets and the Philippine Cynomolgus monkey.
Today the lake is the main source of water supply for the National Power Corporation Hydro Electric Plant. The power plant, founded in 1952, generates an average of 2.8 megawatts. It is used by the National Irrigation Administration to irrigate at least 100 square kilometres of the Riconada towns located downstream and Iriga City. On September 22, 2007, a fish kill in Camarines Sur's Lake Buhi threatened the livelihood of local fishermen; the Bureau of Fisheries and Aquatic Resources stated that it resulted from sulfur dioxide from Iriga City, since the rains by the southwest monsoon loosened the sulfur dioxide from nearby volcanoes. The Philippine Institute of Volcanology and Seismology rejected BFAR's finding. Buhi has 13,238 households. Media related to Lake Buhi at Wikimedia Commons Geographic data related to Lake Buhi at OpenStreetMap
A caldera is a large cauldron-like hollow that forms following the evacuation of a magma chamber/reservoir. When large volumes of magma are erupted over a short time, structural support for the crust above the magma chamber is lost; the ground surface collapses downward into the emptied magma chamber, leaving a massive depression at the surface. Although sometimes described as a crater, the feature is a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Only seven known caldera-forming collapses have occurred since the start of the 20th century, most at Bárðarbunga volcano in Iceland; the word comes from Spanish caldera, Latin caldaria, meaning "cooking pot". In some texts the English term cauldron is used; the term caldera was introduced into the geological vocabulary by the German geologist Leopold von Buch when he published his memoirs of his 1815 visit to the Canary Islands, where he first saw the Las Cañadas caldera on Tenerife, with Montaña Teide dominating the landscape, the Caldera de Taburiente on La Palma.
A collapse is triggered by the emptying of the magma chamber beneath the volcano, sometimes as the result of a large explosive volcanic eruption, but during effusive eruptions on the flanks of a volcano or in a connected fissure system. If enough magma is ejected, the emptied chamber is unable to support the weight of the volcanic edifice above it. A circular fracture, the "ring fault", develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are known as ring dikes. Secondary volcanic vents may form above the ring fracture; as the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions; the total area that collapses may be thousands of square kilometers. Some calderas are known to host rich ore deposits. One of the world's best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario, which formed during the Neoarchean era about 2,700 million years ago.
If the magma is rich in silica, the caldera is filled in with ignimbrite, tuff and other igneous rocks. Silica-rich magma has a high viscosity, therefore does not flow like basalt; as a result, gases tend to become trapped at high pressure within the magma. When the magma approaches the surface of the Earth, the rapid off-loading of overlying material causes the trapped gases to decompress thus triggering explosive destruction of the magma and spreading volcanic ash over wide areas. Further lava flows may be erupted. If volcanic activity continues, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, etc. by subsequent intrusion of magma. A silicic or rhyolitic caldera may erupt hundreds or thousands of cubic kilometers of material in a single event. Small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction and a noticeable drop in temperature around the world.
Large calderas may have greater effects. When Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km3 of material, covering a substantial part of North America in up to two metres of debris. By comparison, when Mount St. Helens erupted in 1980, it released ~1.2 km3 of ejecta. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia. About 74,000 years ago, this Indonesian volcano released about 2,800 cubic kilometres dense-rock equivalent of ejecta; this was the largest known eruption during the ongoing Quaternary period and the largest known explosive eruption during the last 25 million years. In the late 1990s, anthropologist Stanley Ambrose proposed that a volcanic winter induced by this eruption reduced the human population to about 2,000–20,000 individuals, resulting in a population bottleneck. More Lynn Jorde and Henry Harpending proposed that the human species was reduced to 5,000-10,000 people.
There is no direct evidence, that either theory is correct, there is no evidence for any other animal decline or extinction in environmentally sensitive species. There is evidence. Eruptions forming larger calderas are known La Garita Caldera in the San Juan Mountains of Colorado, where the 5,000 cubic kilometres Fish Canyon Tuff was blasted out in eruptions about 27.8 million years ago. At some points in geological time, rhyolitic calderas have appeared in distinct clusters; the remnants of such clusters may be found in places such as the San Juan Mountains of Colorado or the Saint Francois Mountain Range of Missouri. Some volcanoes, such as the large shield volcanoes Kīlauea and Mauna Loa on the island of Hawaii, form calderas in a different fashion; the magma feeding these volcanoes is basalt, silica poor. As a result, the magma is much less viscous than the magma of a rhyolitic volcano, the magma chamber is drained by large lava flows rather than by explosive events; the resulting calderas are known as subsidence calderas and can form more than explosive calderas.
For instance, the caldera atop Fernandina Island collapsed
Tadlac Lake colloquially known as Alligator Lake, is a freshwater crater lake located in Barangay Tadlac, in the municipality of Los Baños of Laguna province in the Philippines. The lake-filled maar is located along the southern shore of Laguna de Bay, the largest lake in the country, with Alligator Lake protruding out of the shore of the larger lake. If not for its slightly-elevated crater rim, Alligator Lake would be wholly engulfed by Laguna de Bay; the crater lake is one of the maars of the Laguna Volcanic Field. It is listed as one of the inactive volcanos in the Philippines by the Philippine Institute of Volcanology and Seismology. Tadlac lake is notable for its history of annual Lake overturns, locally called langal; this phenomenon, rare elsewhere but occurring in Tadlac lake during the cold months of December to February, is the result of trapped carbon dioxide erupting from the deep layers of the lake towards the surface, leading to fish kills due to low levels of dissolved oxygen.
This phenomenon was heightened by the introduction of aquaculture to the lake in the mid-1980s leading to a massive and costly fishkill in 1999, which in turn led to the cessation of aquaculture activities on the lake. Prior to the introduction of aquaculture, Alligator Lake was considered as an oligotrophic lake, having low nutrient content and low algal production, resulting in clear water with high drinking-water quality. Alligator Lake is located in Barangay Tadlac, in the hot springs resort town of Los Baños near the border with Calamba City in the province of Laguna; the lake is contained in a piece of land jutting out to the Laguna de Bay, known as Malilimbas Point, is directly situated below the northeastern slope of Mount Makiling, the highest mountain in the Laguna Volcanic Field. Because of its origin, the lake is replenished only by rainfall; the oval lake is 22.7 ha in surface area with a perimeter of about 1.8 kilometers. It has an average depth of 27 meters so swimming is not recommended because of its depth and the sudden drop along its shoreline.
The lake surface's longest dimension is 650 meters in the NE-SW direction with the widest dimension perpendicular to the longest at 503 meters. The crater rim that separates Alligator Lake from the surrounding Laguna de Bay is thinnest northeast of the lake with only about 40-metre wide piece of land separating it from the larger lake; the Tadlac Barangay Road does not circle the lake. Another road runs west of Alligator lake; the lands around the lake are owned, some owners have established resorts around the lake. The Laguna Lake Development Authority, as mandated by the government, manages Laguna de Bay and its surrounding areas including Alligator Lake. Lake overturns or carbon dioxide eruption from deep within, locally called as langal occurs during the months of December to February. During this period some indigenous fishes of the lake are observed gasping for air near the lake surface; this phenomoenon was hightened by the introduction of aquaculture to the lake in the mid-1980s leading to a massive and costly fishkill in 1999, which in turn led to the cessation of aquaculture activities on the lake.
During the Spanish colonial period, the lake was known as Laguna de los Caimanes. The great number of crocodilians that used to live in its waters gave the lake its name. Today, crocodiles have been extirpated in and around Alligator Lake and Laguna de Bay. Suggested etymologies for the name "tadlac" include a kind of "wild ginger" and a grass related to sugarcane. Documenting field expeditions he conducted during his time with the International Rice Research Institute, Agricultural scientist and journalist Thomas Hargrove noted that "Tadlak" was the Tagalog term for a kind of wild ginger which he described as "pulpy with a red bulb."Alternatively, historian Zeus A. Salazar has suggested that the name tadlac may refer to a local variety sugarcane which he theorized to be common in Laguna and Batangas before the propagation of modern sugarcane, based on linguistic similarities with the local name of Themeda arundinacea in Central Luzon. Starting from 1986, the LLDA authorized the use of 30,000 square metres or about 12%of its total surface the lake for tilapia fish cage aquaculture to help the local fishermen earn a living.
Starting around the same time, the hill on the northern edge of the lake was quarried by its private owner and sold as building materials for home construction. The destruction continued unopposed by the lax management of LLDA, the local government of Los Baños recognized the activity as the right of the land owner to develop his property; this was back when the Philippine Environmental Impact Assessment System was not yet established. In the end, about 7,000–8,000 m2 of earth & rocks were removed and the land was leveled leaving a "cut" on the crater rim, destroying the natural look of the lake. From 1986 until the late 1990s, the lake was used for aquaculture until a massive fishkill occurred in 1999. Through the collaborative efforts of the local leaders and the Laguna Lake Development Authority, aquaculture was stopped saving the lake from further deterioration. From Manila, the lake is about 61 km or an hour drive from KM Zero in Rizal Park to Barangay Tadlac via South Luzon Expressway the National Road.
A park is located on the east side of the lake along Tadlac Barangay Road. The lake can be accessed on through the road west of the lake and through the "cut" north of the lake; the owner of the quarried land had