This chapter elucidates how the foundation framework of the decision support system (DSS) was built using an analytical framework, referring to the conceptual model of Ecosystem-Based Management-Drivers-Pressures-States-Ecosystem Services-Responses (EBM-DPSER). It starts with the introduction of the theoretical foundation of the framework and runs through the quantification of each of the framework’s component. The framework provides robust scientific fundamentals and legitimacy for the DSS since it was constructed using stakeholder and expert-based knowledge. It portrays the dynamics of lake ecosystems and the complex interactions of their constituent components (both abiotic and biotic components and the socio-economic systems). The quantification also results in the weights of each management issue and its components, highlighting their relative importance. Besides becoming the essential inputs in the DSS, the results also present the management problem prioritization, guiding the selection of essential management responses.