Kwan means a large swamp or lake. It is also a local Lanna dialect used only in Phayao. Kwan Phayao is a large swamp in a nearly-half-circlc-moon shape, whose northeastern part is indented. It was caused by the collapse of the earth’s crust 70 million years ago. Hugging Doi Mae Chai which is a high and long mountain range.
Kwan Phayao is a gathering venue of 18 brooks. Later, in 1935, the Department of Fisheries established the Phayao Fresh-water Fishery Station at the origin of the Ing River. When the dam was constructed, it became a large swamp with an average depth of 1.5 metres. Kwan Phayao is the most important source of water in the province and the most significant fresh-water fishery venue of the upper northern region.
Moreover, it is a tourist attraction of Phayao Province, covering an area of 12.831 rai and a habitat of various kinds offish such as Pla Krai-spotted fealhcrback, Pla Sawai-striped catfish, Pla Thepho-black ear catfish, Pla Chin-Scobranch catfish, Pla Nai-carp, and Pla Nin-Nilc tilapia, the famous species of Phayao.