In the process of implementing the River Leader System, some problems have emerged regarding its progress and effects. From the perspective of historical institutionalism, the historical change process of the River Leader System was revealed in this paper. There were two key nodes in the historical change progress of the River Leader System. In 2014, the river leader system promotion was transferred from the local government to the Ministry of Water Resources. In 2016, the River Leader System was recognized by the central government and implemented nationwide. The historical change process of the River Leader System can be divided into three periods: the creation and formation period, the pilot and diffusion period, and the promotion and strengthening period. The change in the river and lake problems was an important driving force for the historical change of the River Leader System. A path dependent phenomenon was mainly reflected in the policy diffusion scope, problem orientation, main tasks and management methods. At present, there are some shortcomings in the River Leader System, such as a lack of inter-provincial coordination, imperfect evaluation mechanism, poorly coordinated management tasks, and insufficient public participation. To solve these problems, some policy recommendations are put forward. In the short term, the River Leader System will be continuously improved and strengthened. In the long term, it will be transformed into the integrated watershed management system.

Among water blooms, cyanobacteria bloom occurs over the widest range and is much more harmful than other blooms. Its occurrence in inland water bodies is affected by many factors, such as meteorology, hydrology, and human activities. Therefore, the study of the causes of cyanobacterial bloom has become a major focus of scholars. The China Knowledge Network Journal Database contains 143 papers from China and abroad from the years 2004 to 2019 that are relevant to the study of cyanobacteria bloom. We begin by analyzing keywords in these studies and creating a keyword distribution map which indicates the factors related to the blooms. Based on parameters such as the frequency of words appearing in the text, the full text of each of the 143 papers is analyzed to form a word cloud created by a program written in Python language. After irrelevant terms are eliminated, the word cloud map can reveal potential factors that were not identified by keywords alone. After completing this macro analysis, we examined approximately 100 related papers from the China Knowledge Network Journal Database and Web of Science Database published from 2014 to 2019. Finally, we summarize the main reasons for the outbreak of water blooms. The factors causing blooms can be divided into natural factors and human factors. Among the natural factors are illumination, water temperature and nutrient salt conditions. The human factors are generally related to large-scale water conservancy projects. This paper analyzes and summarizes these factors, and provides a reference to aid in the prevention and treatment of algal blooms. The information in the paper has a certain practical significance for the protection of water environments.