Evolution trend, treatment process and effect of water ecological environment in Dianchi Lake Basin

In order to summarize the effectiveness and systematically analyze the problems during the comprehensive treatment of Dianchi Lake water environment, the literature research and other methods were used to analyze the water quality evolution process and governance measures of Dianchi Lake. The treatment of Dianchi Lake was divided into four stages: 1) Exploring period (1988-1995), preliminary methods for Dianchi governance against the significant decrease of water quality were explored. 2) Engineering period (1996-2006), the point source pollution control was adopted as the leading governance model in response to the increase in sewage discharge and water intake for industry and agriculture. 3) Systemic treatment period (2007-2015), in 2007, Dianchi Lake was listed as the Major Science and Technology Program for Water Pollution Control and Treatment (Water Projects for short). The central and local governments proposed a comprehensive pollution control idea, with the “six major projects” as the main line, supported by Water Projects, and the basin water pollution systematic treatment was promoted. 4) Precise treatment period (since 2016), a new idea of “scientific, systematic, intensive, lawful” was formed. By strengthening refined management, promoting the tackling of key scientific and technological problems and the application of R&D achievements, the water quality of Dianchi Lake had been improved significantly. However, the water ecological environment of Dianchi Lake was still grim, due to the serious problems such as the shortage of water resources, the heavy load of non-point source pollution in the basin, and the damage to the water ecology. The governance of Dianchi Lake during the 14th Five-Year Plan period should follow the idea of basin water quality target management, comprehensively promote the governance and management of water resources, water environment and water ecology, accelerate the water environmental infrastructure construction, strengthen the basin water replacement, and restore and maintain the functions of the lake ecosystem.