Governance of information spaces in corporate Web sites and Intranet portals has become more and more important for organizations. However, there is still a lack of methodologies for managing information in the "Web era". To establish the information governance methodology for the "Web era", understanding of the mechanism of growth and maturing patterns of information spaces in Web sites would be indispensable. The motivation of our research is to clarify the conceptual framework to assess WIS evolution from information perspective instead of the usual systems perspective, and to seek for in-depth understanding of maturing patterns of WISs based on the framework. In this paper, we first discusses about several central concepts related to the information aspect of WIS and information space, then after discussing about the framework for evaluating the maturity of Web sites we propose a growth model of local government Web sites based on a survey study. In order to describe the growth process of local government Web sites, several cases of local government Web site evolution are also illustrated.