According to local records, the original thing, north and south, four seas, and then land. During the spring and summer of the seventh year of Xianfeng in Qing Dynasty (1857), heavy rains caused disasters, flash floods broke out, and the undercurrent channel was blocked, so that the water in the western suburb plain could not be discharged, which made this basin with an altitude of 2000 meters form a plateau Haizi. Later, there were many aquatic plants such as reeds and cattails in the lake, so it was named Caohai. The Weining fine fish 1-2 cm long, tender and delicious, enjoys a good reputation throughout the country. It also produces dozens of wading birds such as long-tailed pheasants, golden pheasants, cranes, geese and wild ducks. It is also home to red-crowned cranes, black-necked cranes and storks. Artificial breeding of nutria, lynx, mink, silver fox and other genera has a high reproductive rate. The lake is rich in aquatic animals and plants such as fish, shrimp and cattail, and is home to more than 100 exotic waterfowl. The only highland crane in the world, the black-necked crane, overwinters here every year.
Caohai is warm in winter and has a pleasant climate. In late spring, colorful and moving azaleas bloom in a large area around Caohai. Caohai is the most beautiful in autumn. The aquatic plants in the lake are competing to open, and strings of yellow flowers, red flowers and white flowers bloom in the clear water, and the flowers float with the water waves, such as entering a fairyland. Winter in Caohai is the best season to watch black-necked cranes. Whenever the weather is fine, standing on the shore and looking out, the water and sky are one color, the smoke is vast, flowers are in full bloom, kites are flying, fish are jumping, and geese fly over autumn, which makes people feel relaxed and happy.
Caohai is not only rich in resources, but also beautiful all year round, suitable for rain or shine. Boarding the seascape building in the suburbs, the surrounding mountains are overlapping and criss-crossing, and the mountain villages are blurred. The lake is blue, the water and the sky are the same, and there are a little fishing boats. There is a Penglai Island, isolated in the middle of the lake, with shady trees, exquisite pavilions and butterflies, which is called "water park".
There are Han, Yi, Hui and Miao nationalities living around Caohai. During festivals, people of all ethnic groups race horses, play lusheng, sing and dance here, which is very lively.
Caohai is not only a good place to carry out tourism activities, but also an ideal place for scientific investigation. Experts at home and abroad have investigated the topography, landform, soil, hydrology, climate, water quality, terrestrial vegetation, aquatic vegetation, zooplankton, phytoplankton, amphibians, fish, birds, amphibians and reptiles in Caohai area, and Caohai has become the focus of World Wildlife Fund (WWF) and International Crane Foundation (ICF).