The second-level tributary of the second Songhua River of Yitong River is the mother river of Changchun. The natural length of the urban section of Changchun City (from the lower section of the Xinlicheng Reservoir dam to the Wanbao sluice) is about 47.137km, and the middle section of the river (Sihua sluice to the south) The section around the city is about 15.88km in length, the average width of the river is 140m, the narrowest point is 110m, the average slope of the middle section of the river is about 0.5‰, the average water depth is about 2.5m, and the total water body capacity is about 6.3 million m3. Since 1986, Changchun City has renovated the Yitong River many times, and basically completed the greening and flood control construction of the river in the city section. After the construction of the upstream Xinlicheng Reservoir, the Yitong River lost its stable source water supply and has become the main channel for carrying natural rainfall and urban drainage. Water pollution, river siltation, and loss of water ecological functions have caused the middle section of the Yitong River to become black. Smelly body of water.