The Chao Phraya River is the largest river in Thailand. It is formed from the four main rivers in the northern part of Thailand, the Ping, Wang, Yom and Nan rivers and drains an area of about 178,000 sq. km. The Chao Phrnya River is the largest river of the country which drains an area of about 178,000 sq. km and holding a volume of 30,000 million cubic meters. Geographically, it is formed from four main rivers in the northern part of Thailand, viz. the Ping, Wang, Yom and Nan rivers which meet at Nakhon Sa~an. This is one of the most important rivers with about 380 km from the origin of Nakhon Sawan to the outfall at Samut Prakarn.
The benefits derived from this river are multifarious, for industries, fisheries, agriculture, transportation, domestic consumption, etc. wherein most of the communities and consumers especially in Bangkok depend largely on this river. There are also many commercial establishments which benefit from both sides of the river, such as restaurnnts, hotels, condominiums, and piers. In the contrary, those people who get the most benefit from the river have done nothing to-protect it, im-tead, they continue to discharge po1tutants into the river.
The continuing deterioration of water quality in the Chao Phraya River has become a serious environmental concern brought about by the discharge of industrial, domestic, and agricultural wastewaters into the river. In 1990, the total BOD discharged by domestic sewage and industrial waste was estimated to be 183,634 kg of
BOD dayl. It has been reported that the upper part of the river though not much affected by pollution, has shown slight indications of pollution at certain places. The water quality in the middle part of the river has begun to be polluted at a rather high rate especially at the location where water is abstracted for producing
water supply to the city of Bangkok. Apparently, the lower part has been indicated as highly polluted, with dissolved oxygen levels approaching zero.
The mighty Chao Phraya River has been exhaustively used to its full extent for hundreds of years for consumption, agriculture, fishery, industries, communication and worse than anything else, as a receiving body for liquid and solid wastes from all sorts of human activities. In recent modern times, the pollution of this
river is becoming a glaring problef1.1 due to excessive organic waste load entering the river has already crossed the "Natural Assimilative Capacity" of the river.