This chapter elaborates on the monetization methods of the ecosystem services trade-offs related to the ecosystem-based management driver(s)-pressure(s)-state(s)-ecosystem services-response(s) (EBM-DPSER) framework and the calculation methods of the sustainability index (SI), which are the principal final outputs of the decision support system (DSS). The included parameters in the economic valuation are the influence of land-use best management practice on clean water provisioning, the impacts of water level management on ikan bilih habitat provisioning, the impacts of water level management on loss of rice production, no-catch zone establishment, and macroplastic management. We applied several economic valuation methods, such as market price approaches, habitat replacement cost, benefit transfers, and contingent valuation methods (CVM). We identified several uncertainties that need to be incorporated and underlined important updates for future research and DSS development. The results of the benefit-cost analysis are vital for the decision-making process in the area. Meanwhile, the SI, although newly introduced, can set a benchmark for future lake management.