With increasing urbanization and population growth, humankind faces multiple environmental challenges. Stresses on limited resources, especially water resources, are now greater than ever before. Watershed monitoring and management are important components of programs to abate water resource stresses. The increasing water quantity and quality monitoring has produced a need for better data management techniques to manage the vast amount of watershed monitoring data being observed. These data must be stored, error checked, manipulated, retrieved and shared with the watershed management community. The web-based data visualization and analysis technology has played a critical role in all aspects of watershed management. Especially in recent years, computer-assisted data analysis has matured enormously. This maturing technology makes web-based visualization and analysis technology change its role to become an integrated system which combines applications of databases, and internet technology. The main objective of this study is to develop a prototype system which has ability of data visualization and analysis. Microsoft SQL Server is used to build a comprehensive database, which includes all datasets collected by OWML. A Web-Based Data Visualization and Analysis System which provides an integrated interface for permitted users to explore, analyze and download data has been developed. / Master of Science