For the government, indicator measurements are a major means of demonstrating the legitimacy of policy. To provide a reason as to why a policy continues to exist, the government must utilize the indicator to justify its actions in carrying out its policy. Although indicator measurements are sophisticated, they may provide policy-makers with means to keep on monitoring and modifying their policy goals. In doing so, the main purpose of this paper is to measure the quality of the water of the Taipei Water Source Domain by comparison. The main point of discussion concerns whether is it a good way by means of land-use regulations to maintain the quality of water supply. The analysis proceeds as follows. First of all, the people who live in the Taipei Water Source Domain are interviewed. Secondly, by combining the results of the interview with the watershed sustainability indicator, this paper includes a set of indicators, including society, the environment, and the economy. Finally, a well-developed methodology, the Analytic Network Process, is employed to analyze the managerial performance of the Taipei Water Source Domain. By comparing four water conservation areas, the results show that the Taipei Water Source Domain has relatively better performance. The result also shows that land management, which integrates water, soil, and forest management, influences the performance of the water conservation area the most, and in turn outlines the importance of the special characteristic of the Taipei Water Source Domain as it is the only water conservation area in Taiwan designated by the Urban Plan Act. Although the Urban Plan Act in particular gives the Taipei Water Management Office the capacity of land management, the paper finally provides some suggestions for the Taipei Water Source Domain to improve the existing problems.