The Nanjing section of the Yangtze River, a vital component of the Yangtze River Economic Belt, faces significant economic losses to its riparian industries due to pervasive water pollution. This paper, grounded in environmental economics theory, systematically investigates the economic impacts of water pollution on riparian industries in this critical region. It specifically analyzes the diverse pathways through which pollutants, including Chemical Oxygen Demand (COD), Ammonia Nitrogen (NH3-N), heavy metals, and microplastics, affect key sectors such as manufacturing, agriculture, and tourism, as well as public health. The study reveals that water pollution has led to substantial economic losses, including a reduction in regional GDP, employment, investment, and consumption, with industrial wastewater discharge alone causing hundreds of millions of RMB in losses, peaking in 2018. These impacts are transmitted through various mechanisms: depletion of fishery resources, decreased tourism revenue, increased water treatment costs, real estate value depreciation, and higher industrial production and compliance expenditures. In response, the paper proposes a suite of comprehensive governance strategies. These include fostering basin-wide collaborative governance with ecological compensation mechanisms, targeted control of microplastic pollution, internal pollution management through sediment dredging, and robust aquatic ecological restoration initiatives. Ultimately, these measures are crucial for promoting the coordinated development of the economy and the environment, ensuring the long-term sustainability of the Nanjing section and the broader Yangtze River Economic Belt.