Tropical Depression Nineteen (1970)
Encyclopedia
Tropical Depression Nineteen in 1970 was the wettest known tropical cyclone
to affect the United States
territory of Puerto Rico
. The long-lived depression formed on September 24 just off the west coast of Africa, and for several days maintained a general westward track. It passed through the Lesser Antilles
on October 1, and later stalled in the eastern Caribbean Sea. On October 8, the depression crossed over the Dominican Republic
, and subsequently it accelerated to the northeast. It was declassified as a tropical cyclone on October 12, although its remnants persisted for another week before dissipating in the westerlies
near the Azores
.
The depression produced heavy rainfall in the Lesser Antilles, reaching 12 in (304.8 mm) on Barbados
; it left three deaths and moderate damage on the island. Another death was reported in the United States Virgin Islands
. Torrential rainfall on Puerto Rico inflicted heavy damage, totaling $65 million (1970 USD, $ USD). The highest precipitation total was 41.68 in (1,058.7 mm) in Jayuya
, of which 17 in (431.8 mm) fell in a 24 hour period. Most of the damage can be attributed to damaged sugar cane and coffee crops. At least 18 people were killed on the island, and the system was considered one of the worst disasters in Puerto Rican history.
on September 22 over western Africa. The system exited the west coast of Africa the next day, and on September 24 it developed
into a tropical depression
about 95 mi (152.9 km) southwest of Conakry
, Guinea
. The depression moved generally westward, gradually intensifying to attain peak winds of 35 mph (56.3 km/h) by September 25. A nearby upper-level trough
— an elongated area of low pressure
— hindered further strengthening, and on October 1 the depression struck the island of Saint Lucia
. As it crossed the Lesser Antilles
, its winds and barometric pressure
approached the values of a tropical storm.
In the Caribbean, the trough caused the depression to slow to a westward drift, resulting in several days of heavy rainfall in the region, particularly Puerto Rico
. One forecast on October 5 anticipated a continued westward track toward Jamaica
. Instead, the depression turned to the north the next day under the influence of the upper-level westerlies
. On October 7, the depression attained its lowest pressure of 1000 mbar
(29.53 inHg
), off the southern coast of Hispaniola
. The next day, it made landfall
in Peravia Province in the Dominican Republic
. After crossing the country and exiting into the Atlantic Ocean, the depression accelerated to the northeast, followed by an eastward turn on October 10 before another turn to the northeast. By October 12, the depression could no longer be classified as a tropical cyclone, although satellite imagery indicated its remnants continued northeastward. On October 15 the system turned to the west, suppressed by a strong high pressure area
to its north. It re-intensified while crossing through the Azores
, attaining a pressure of 994 mbar. It turned to the northwest and was absorbed into the westerlies on October 20.
through Guadeloupe
to prepare for floods, high seas, and gale-force gusts. On October 10, a warning to be on guard against gusts was issued to owners of light aircraft in Puerto Rico and the Virgin Islands. As it crossed through the islands, the depression produced heavy rainfall, including 8.9 in (226.1 mm) on Saint Lucia, 2.19 in (55.6 mm) on Dominica, and 12 in (304.8 mm) on Barbados. In the latter island, the depression left 200 people homeless, caused $500,000 in damage, and killed three people.
Heavy rains impacted the U.S. Virgin Islands
, including a total of 11.4 in (289.6 mm) recorded by the National Park Service
on Saint John
. The rains caused flooding across the territory, washing out roads and destroying several houses. One boy was swept away by the floodwaters, although he was rescued by two people. A girl was also swept by the floods and drowned. The desalination plant on Saint Croix was damaged during the floods, temporarily stopping the supply of drinking water; water from Puerto Rico had to be shipped to provide the 700,000 gallons needed daily. On St. Thomas, the main airport
was closed for several days.
For six days, the depression dropped rainfall across the northern Caribbean, particularly in Puerto Rico. The highest overall rainfall total was 41.68 in (1,058.7 mm), recorded at a station near Jayuya
in the center of the island. This was the highest rainfall total from a tropical cyclone on record in Puerto Rico, surpassing that of the deadly hurricanes of 1928
and 1899, which produced 29.6 in (751.8 mm) and 23 in (584.2 mm), respectively. The station at Jayuya also recorded 17 in (431.8 mm) in 24 hours. Four other locations reported over 30 in (762 mm). Such heavy rainfall caused 20 rivers to swell above flood stages.
The depression left 10,000 people homeless across Puerto Rico, with 3,000 housed in emergency shelter
s in San Juan
. At least 600 houses were destroyed and another 1,000 damaged. Damage was particularly severe in Barceloneta
, Aibonito
, and Coamo
. Across the island, the depression affected at least 40 state roads, with fifteen blocked by landslides, and eleven bridges destroyed. Flooding forced the closure of Puerto Rico Highway 2
between Manati
and Barceloneta. The depression left more than $40 million (1970 USD, $ USD) in crop damage, primarily to sugar cane and coffee
, as reported by William R. Poage
, the chair of the House Agricultural Committee
. Throughout Puerto Rico, the depression caused damage estimated at $65 million (1970 USD, $ USD), as well as at least 18 confirmed fatalities. A reported six months after the depression indicated there were 34 people missing, although their status is unknown.
In the aftermath of the disaster, Luis A. Ferre
, the Governor of Puerto Rico
, declared an state of emergency
over the whole island, asking for $10 million (1970 USD) in federal aid. On October 12, two days after the rains subsided, President
Richard Nixon
declared the territory as a disaster area. Ferre also appeared in a telethon to raise funds for the homeless. The National Guard
, the Red Cross, and other volunteer groups helped the displaced persons. In all, the disaster was described as one of the worst in Puerto Rico history
. The Governor of the Virgin Islands, Melvin Evans, requested aid similar to Puerto Rico, and that territory was also declared a federal disaster area about a week after the rains ended. The heavy rainfall in the Virgin Islands caused a marked Dinoflagellate
algal bloom
in the days after the rains ended.
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
to affect the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
territory of Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
. The long-lived depression formed on September 24 just off the west coast of Africa, and for several days maintained a general westward track. It passed through the Lesser Antilles
Lesser Antilles
The Lesser Antilles are a long, partly volcanic island arc in the Western Hemisphere. Most of its islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean, with the remainder located in the southern Caribbean just north of South America...
on October 1, and later stalled in the eastern Caribbean Sea. On October 8, the depression crossed over the Dominican Republic
Dominican Republic
The Dominican Republic is a nation on the island of La Hispaniola, part of the Greater Antilles archipelago in the Caribbean region. The western third of the island is occupied by the nation of Haiti, making Hispaniola one of two Caribbean islands that are shared by two countries...
, and subsequently it accelerated to the northeast. It was declassified as a tropical cyclone on October 12, although its remnants persisted for another week before dissipating in the westerlies
Westerlies
The Westerlies, anti-trades, or Prevailing Westerlies, are the prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east, and steer extratropical...
near the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
.
The depression produced heavy rainfall in the Lesser Antilles, reaching 12 in (304.8 mm) on Barbados
Barbados
Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...
; it left three deaths and moderate damage on the island. Another death was reported in the United States Virgin Islands
United States Virgin Islands
The Virgin Islands of the United States are a group of islands in the Caribbean that are an insular area of the United States. The islands are geographically part of the Virgin Islands archipelago and are located in the Leeward Islands of the Lesser Antilles.The U.S...
. Torrential rainfall on Puerto Rico inflicted heavy damage, totaling $65 million (1970 USD, $ USD). The highest precipitation total was 41.68 in (1,058.7 mm) in Jayuya
Jayuya, Puerto Rico
Jayuya is a municipality of Puerto Rico located in the mountainous center region of the island, north of Ponce; east of Utuado; and west of Ciales. Jayuya is spread over 18 wards and Jayuya Pueblo...
, of which 17 in (431.8 mm) fell in a 24 hour period. Most of the damage can be attributed to damaged sugar cane and coffee crops. At least 18 people were killed on the island, and the system was considered one of the worst disasters in Puerto Rican history.
Meteorological history
The origins of the depression were identified as a tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
on September 22 over western Africa. The system exited the west coast of Africa the next day, and on September 24 it developed
Tropical cyclogenesis
Tropical cyclogenesis is the term that describes the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which mid-latitude cyclogenesis occurs...
into a tropical depression
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
about 95 mi (152.9 km) southwest of Conakry
Conakry
Conakry is the capital and largest city of Guinea. Conakry is a port city on the Atlantic Ocean and serves as the economic, financial and cultural centre of Guinea with a 2009 population of 1,548,500...
, Guinea
Guinea
Guinea , officially the Republic of Guinea , is a country in West Africa. Formerly known as French Guinea , it is today sometimes called Guinea-Conakry to distinguish it from its neighbour Guinea-Bissau. Guinea is divided into eight administrative regions and subdivided into thirty-three prefectures...
. The depression moved generally westward, gradually intensifying to attain peak winds of 35 mph (56.3 km/h) by September 25. A nearby upper-level trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
— an elongated area of low pressure
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
— hindered further strengthening, and on October 1 the depression struck the island of Saint Lucia
Saint Lucia
Saint Lucia is an island country in the eastern Caribbean Sea on the boundary with the Atlantic Ocean. Part of the Lesser Antilles, it is located north/northeast of the island of Saint Vincent, northwest of Barbados and south of Martinique. It covers a land area of 620 km2 and has an...
. As it crossed the Lesser Antilles
Lesser Antilles
The Lesser Antilles are a long, partly volcanic island arc in the Western Hemisphere. Most of its islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean, with the remainder located in the southern Caribbean just north of South America...
, its winds and barometric pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
approached the values of a tropical storm.
In the Caribbean, the trough caused the depression to slow to a westward drift, resulting in several days of heavy rainfall in the region, particularly Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
. One forecast on October 5 anticipated a continued westward track toward Jamaica
Jamaica
Jamaica is an island nation of the Greater Antilles, in length, up to in width and 10,990 square kilometres in area. It is situated in the Caribbean Sea, about south of Cuba, and west of Hispaniola, the island harbouring the nation-states Haiti and the Dominican Republic...
. Instead, the depression turned to the north the next day under the influence of the upper-level westerlies
Westerlies
The Westerlies, anti-trades, or Prevailing Westerlies, are the prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east, and steer extratropical...
. On October 7, the depression attained its lowest pressure of 1000 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
(29.53 inHg
Inch of mercury
Inches of mercury, ' is a unit of measurement for pressure. It is still widely used for barometric pressure in weather reports, refrigeration and aviation in the United States, but is seldom used elsewhere....
), off the southern coast of Hispaniola
Hispaniola
Hispaniola is a major island in the Caribbean, containing the two sovereign states of the Dominican Republic and Haiti. The island is located between the islands of Cuba to the west and Puerto Rico to the east, within the hurricane belt...
. The next day, it made landfall
Landfall (meteorology)
Landfall is the event of a tropical cyclone or a waterspout coming onto land after being over water. When a waterspout makes landfall it is reclassified as a tornado, which can then cause damage inland...
in Peravia Province in the Dominican Republic
Dominican Republic
The Dominican Republic is a nation on the island of La Hispaniola, part of the Greater Antilles archipelago in the Caribbean region. The western third of the island is occupied by the nation of Haiti, making Hispaniola one of two Caribbean islands that are shared by two countries...
. After crossing the country and exiting into the Atlantic Ocean, the depression accelerated to the northeast, followed by an eastward turn on October 10 before another turn to the northeast. By October 12, the depression could no longer be classified as a tropical cyclone, although satellite imagery indicated its remnants continued northeastward. On October 15 the system turned to the west, suppressed by a strong high pressure area
High pressure area
A high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
to its north. It re-intensified while crossing through the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
, attaining a pressure of 994 mbar. It turned to the northwest and was absorbed into the westerlies on October 20.
Preparations, impact, and aftermath
Around October 3, forecasters advised residents on islands from Barbados and St. VincentSaint Vincent (island)
Saint Vincent is a volcanic island in the Caribbean. It is the largest island of the chain called Saint Vincent and the Grenadines. It is located in the Caribbean Sea, between Saint Lucia and Grenada. It is composed of partially submerged volcanic mountains...
through Guadeloupe
Guadeloupe
Guadeloupe is an archipelago located in the Leeward Islands, in the Lesser Antilles, with a land area of 1,628 square kilometres and a population of 400,000. It is the first overseas region of France, consisting of a single overseas department. As with the other overseas departments, Guadeloupe...
to prepare for floods, high seas, and gale-force gusts. On October 10, a warning to be on guard against gusts was issued to owners of light aircraft in Puerto Rico and the Virgin Islands. As it crossed through the islands, the depression produced heavy rainfall, including 8.9 in (226.1 mm) on Saint Lucia, 2.19 in (55.6 mm) on Dominica, and 12 in (304.8 mm) on Barbados. In the latter island, the depression left 200 people homeless, caused $500,000 in damage, and killed three people.
Heavy rains impacted the U.S. Virgin Islands
United States Virgin Islands
The Virgin Islands of the United States are a group of islands in the Caribbean that are an insular area of the United States. The islands are geographically part of the Virgin Islands archipelago and are located in the Leeward Islands of the Lesser Antilles.The U.S...
, including a total of 11.4 in (289.6 mm) recorded by the National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
on Saint John
Saint John, U.S. Virgin Islands
Saint John is an island in the Caribbean Sea and a constituent district of the United States Virgin Islands , an unincorporated territory of the United States. St...
. The rains caused flooding across the territory, washing out roads and destroying several houses. One boy was swept away by the floodwaters, although he was rescued by two people. A girl was also swept by the floods and drowned. The desalination plant on Saint Croix was damaged during the floods, temporarily stopping the supply of drinking water; water from Puerto Rico had to be shipped to provide the 700,000 gallons needed daily. On St. Thomas, the main airport
Cyril E. King Airport
-Cargo:*Ameriflight *Four Star Aviation*FedEx-Accidents and incidents:On December 28, 1970, Trans Caribbean Airways Flight 505 made a hard landing and ran off the side of the runway. Two of the 48 passengers died in the subsequent fire....
was closed for several days.
For six days, the depression dropped rainfall across the northern Caribbean, particularly in Puerto Rico. The highest overall rainfall total was 41.68 in (1,058.7 mm), recorded at a station near Jayuya
Jayuya, Puerto Rico
Jayuya is a municipality of Puerto Rico located in the mountainous center region of the island, north of Ponce; east of Utuado; and west of Ciales. Jayuya is spread over 18 wards and Jayuya Pueblo...
in the center of the island. This was the highest rainfall total from a tropical cyclone on record in Puerto Rico, surpassing that of the deadly hurricanes of 1928
1928 Okeechobee Hurricane
The Okeechobee hurricane, or San Felipe Segundo hurricane, was a deadly hurricane that struck the Leeward Islands, Puerto Rico, the Bahamas, and Florida in September of the 1928 Atlantic hurricane season...
and 1899, which produced 29.6 in (751.8 mm) and 23 in (584.2 mm), respectively. The station at Jayuya also recorded 17 in (431.8 mm) in 24 hours. Four other locations reported over 30 in (762 mm). Such heavy rainfall caused 20 rivers to swell above flood stages.
The depression left 10,000 people homeless across Puerto Rico, with 3,000 housed in emergency shelter
Emergency shelter
Emergency shelters are places for people to live temporarily when they can't live in their previous residence, similar to homeless shelters. The main difference is that an emergency shelter typically specializes in people fleeing a specific type of situation, such as natural or man-made disasters,...
s in San Juan
San Juan, Puerto Rico
San Juan , officially Municipio de la Ciudad Capital San Juan Bautista , is the capital and most populous municipality in Puerto Rico, an unincorporated territory of the United States. As of the 2010 census, it had a population of 395,326 making it the 46th-largest city under the jurisdiction of...
. At least 600 houses were destroyed and another 1,000 damaged. Damage was particularly severe in Barceloneta
Barceloneta, Puerto Rico
Barceloneta is a municipality in Puerto Rico and is located in the north region, bordering the Atlantic Ocean, north of Florida, east of Arecibo and west of Manati. Barceloneta is spread over 3 wards and Barceloneta Pueblo...
, Aibonito
Aibonito, Puerto Rico
Aibonito is a small mountain town in Puerto Rico located in the Mountain range of Cayey, north of Salinas; south of Barranquitas and Comerio; east of Coamo; and west of Cidra, and Cayey. Aibonito is spread over 8 wards and Aibonito Pueblo...
, and Coamo
Coamo, Puerto Rico
Coamo is a municipality in Puerto Rico located in the southern region, north of Santa Isabel; south of Orocovis and Barranquitas; east of Villalba and Juana Díaz; and west of Aibonito and Salinas. Coamo is spread over 10 wards and Coamo Pueblo...
. Across the island, the depression affected at least 40 state roads, with fifteen blocked by landslides, and eleven bridges destroyed. Flooding forced the closure of Puerto Rico Highway 2
Puerto Rico Highway 2
Puerto Rico Highway 2, the longest highway in the Commonwealth of Puerto Rico at about 156 miles long, connects San Juan to Ponce....
between Manati
Manatí, Puerto Rico
Manatí is a municipality of Puerto Rico in the northern coast, north of Morovis and Ciales; east of Florida and Barceloneta; and west of Vega Baja. Manatí is spread over 8 wards and Manatí Pueblo...
and Barceloneta. The depression left more than $40 million (1970 USD, $ USD) in crop damage, primarily to sugar cane and coffee
Coffee
Coffee is a brewed beverage with a dark,init brooo acidic flavor prepared from the roasted seeds of the coffee plant, colloquially called coffee beans. The beans are found in coffee cherries, which grow on trees cultivated in over 70 countries, primarily in equatorial Latin America, Southeast Asia,...
, as reported by William R. Poage
William R. Poage
William Robert Poage was a Texas politician.Poage was born in Waco, Texas and served in the United States Navy during World War I. He served in the Texas House of Representatives from 1925 to 1929, and in the Texas Senate from 1931 to 1937.In 1936, Poage was elected to the House of Representatives...
, the chair of the House Agricultural Committee
United States House Committee on Agriculture
The U.S. House Committee on Agriculture, or Agriculture Committee is a standing committee of the United States House of Representatives. The House Committee on Agriculture has general jurisdiction over federal agriculture policy and oversight of some federal agencies, and it can recommend funding...
. Throughout Puerto Rico, the depression caused damage estimated at $65 million (1970 USD, $ USD), as well as at least 18 confirmed fatalities. A reported six months after the depression indicated there were 34 people missing, although their status is unknown.
In the aftermath of the disaster, Luis A. Ferre
Luis A. Ferré
Don Luis Alberto Ferré Aguayo was a Puerto Rican engineer, industrialist, politician, philanthropist, and a patron of the arts. He was the third Governor of the Commonwealth of Puerto Rico from 1969 to 1973, and the founding father of the New Progressive Party which advocates for Puerto Rico...
, the Governor of Puerto Rico
Governor of Puerto Rico
The Governor of Puerto Rico is the Head of Government of the Commonwealth of Puerto Rico. Since 1948, the Governor has been elected by the people of Puerto Rico...
, declared an state of emergency
State of emergency
A state of emergency is a governmental declaration that may suspend some normal functions of the executive, legislative and judicial powers, alert citizens to change their normal behaviours, or order government agencies to implement emergency preparedness plans. It can also be used as a rationale...
over the whole island, asking for $10 million (1970 USD) in federal aid. On October 12, two days after the rains subsided, President
President of the United States
The President of the United States of America is the head of state and head of government of the United States. The president leads the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces....
Richard Nixon
Richard Nixon
Richard Milhous Nixon was the 37th President of the United States, serving from 1969 to 1974. The only president to resign the office, Nixon had previously served as a US representative and senator from California and as the 36th Vice President of the United States from 1953 to 1961 under...
declared the territory as a disaster area. Ferre also appeared in a telethon to raise funds for the homeless. The National Guard
Puerto Rico National Guard
The Puerto Rico National Guard is the component of the United States National Guard in the U.S. Territory of Puerto Rico. It comprises both Army and Air National Guard components with a total authorized strength of 10,000 soldiers and airmen. The Constitution of the United States specifically...
, the Red Cross, and other volunteer groups helped the displaced persons. In all, the disaster was described as one of the worst in Puerto Rico history
History of Puerto Rico
The history of Puerto Rico began with the settlement of the archipelago of Puerto Rico by the Ortoiroid people between 3000 and 2000 BC. Other tribes, such as the Saladoid and Arawak Indians, populated the island between 430 BC and 1000 AD. At the time of Christopher Columbus's arrival in the New...
. The Governor of the Virgin Islands, Melvin Evans, requested aid similar to Puerto Rico, and that territory was also declared a federal disaster area about a week after the rains ended. The heavy rainfall in the Virgin Islands caused a marked Dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
algal bloom
Algal bloom
An algal bloom is a rapid increase or accumulation in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically, only one or a small number of phytoplankton species are involved, and some blooms may be recognized by discoloration...
in the days after the rains ended.