The Tunasan River also referred to as the Tunasan-Cuyab River, is a river system in the 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...

. This river begins in Dasmariñas, Cavite

Dasmariñas, Cavite

The City of Dasmariñas is a first class city in the province of Cavite, Philippines. It is located approximately 30 kilometers south of Manila. According to the 2007 census, it has a population of 556,330 people, making it before the most populous municipality in the Philippines before it was...

, and ends 9 kilometers later at the border of Muntinlupa City

Muntinlupa City

The City of Muntinlupa is the southernmost city in Philippine National Capital Region. It is bordered on the north by Taguig City; to the northwest by Parañaque City; by Las Piñas City to the west; to the southwest by the city of Bacoor, Cavite; by the city of San Pedro, Laguna; and by Laguna de...

, and San Pedro, Laguna

San Pedro, Laguna

The City of San Pedro is a first class Municipality in the province of Laguna, Philippines. It is named after its patron saint, Saint Peter. San Pedro is Laguna's gateway to Metro Manila since it lies on the boundary with Muntinlupa City, Metro Manila's southernmost city...

. It is one of 21 major tributaries of Laguna de Bay

Laguna de Bay

Laguna de Bay is the largest lake in the Philippines and the third largest freshwater lake in Southeast Asia after Tonle Sap in Cambodia and Lake Toba in Sumatra, Indonesia. It is on the island of Luzon between the provinces of Laguna to the south and Rizal to the north...

.

The river system has six adjoining creeks:

• There are two in San Pedro, Laguna and Dasmariñas, Cavite
• Three creeks joins the system from the ponds of The Filipinas Golf Club, and
• The last one connects from the drainage system of RMT Complex.

The depth of the Tunasan currently varies from two meters to 0.25 meters

Tunasan got its name from a medicinal plant, the Opuntia tuna variety of prickly pears, which the Spanish imported from Mexico and the West Indies when they colonized the Philippines.

The tunasan received media attention in 1994 and 1995 due to a series of "fishkill

Fishkill

Fishkill or Fish Kill is derived from the Dutch term Vis Kill, meaning "creek full of fish".Fishkill or Fish Kill may also refer to:-Communities:*Fishkill , New York, a town in Dutchess County...

s" caused by the high Biochemical Oxygen Demand

Biochemical oxygen demand

Biochemical oxygen demand or B.O.D. is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for...

 from decomposing water lilies

Nymphaeaceae

Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...

, and by the profusion of residential wastes that find their way into the river during the rainy season.