The root cause of increasingly severe water pollution lies in the combined effects of multiple factors. Industrial pollution is the main source of pollution. About 62% of the more than 21000 petrochemical enterprises in China are located along the Yangtze River and Yellow River. A large amount of untreated industrial wastewater is directly discharged into rivers, containing heavy metals such as copper, cadmium, mercury, and benzene organic toxins. These pollutants not only poison aquatic organisms, but also endanger human health through the food chain. Agricultural non-point source pollution can also not be ignored. The use of pesticides and fertilizers continues to increase, but the actual utilization rate is less than 30%. Residual chemicals are washed into the water by rain, resulting in 82% of Rivers and Lakes being polluted to varying degrees, causing economic losses of up to 37.7 billion yuan every year. The urban expansion has exacerbated the problem of domestic pollution, with an annual sewage discharge of 34 billion tons in cities across the country. The indiscriminate discharge of domestic sewage and garbage has turned once clear rivers such as Suzhou River into "black water rivers", and even led to the ecological tragedy of "fish and shrimp are unparalleled in the 1970s, and toilet seats cannot be washed clean in the 1980s".

The extensive economic growth model is a deep-seated incentive. The industrial paradigm of heavy chemical industry layout along the Yangtze River has long existed, and this "high water consumption and high pollution" industrial structure is seriously mismatched with the spatial distribution of water resources. The northern region concentrates 60% of the country's water demand industries but only owns 20% of water resources, forcing enterprises to frequently violate regulations on water discharge. Environmental governance lags behind the pace of economic development. 80% of the 5 million tons of sewage discharged daily in Shanghai are industrial wastewater, but the treatment capacity is seriously insufficient, leading to the risk of Huangpu River becoming two Suzhou rivers. Regulatory loopholes exacerbate the problem, with about 45% of small and medium-sized enterprises engaging in illegal discharge, and 90% of domestic sewage in rural areas being discharged without treatment, creating a complex situation of intertwined point source and non-point source pollution.

The weak public awareness of environmental protection further amplifies the pollution effect. A survey shows that residents around the river are still accustomed to throwing household waste, damaged vegetables and other waste into the water. White pollution such as plastic products accumulates over the years and infiltrates deep water bodies. This "throw it away" behavior pattern has turned 40% of urban inland rivers into smelly ditches. Global climate change has intensified the diffusion of pollution. Frequent rainfall events have made it easier for pollutants to migrate in large scale through surface runoff. The outbreak of leptospirosis in a certain place in 2019 was caused by the diffusion of polluted water through rainstorm. The interaction of multiple factors has led to a vicious cycle of water resource protection where the speed of governance cannot keep up with the speed of pollution.