Abstract:Water quality of Rizhao reservoir is rather good, which can meet water supply requirement of the whole city. However, some factors ,such as external contaminants and sediment pollution will affect water quality of the reservoir. Additionally, the main pollutant TN cut load is bigger. Thus, relevant departments should strengthen the environment protection as soon as possible to improve water supply of Rizhao reservoir safety and sustainability. As an important water resource in Rizhao city, Rizhao reservoir play an important part in city living and industry. Accompanying with rapid development of city scale and economy, security and sustainability of water supply will directly affect sustainable development of national economy.