Assessing water and environmental carrying capacity (WECC) requires a holistic approach that integrates ecological and hydrological aspects. This study introduces a novel integrated framework that couples projections of ecological footprint (EF), biological capacity (BC), and the water stress index (WSI) to evaluate WECC under climate change scenarios. The framework is applied to the Zarrinehrud Basin, the primary inflow source for Lake Urmia—one of the world's largest saltwater lakes—to support ecosystem preservation and sustainable development. Detailed time series analyses of BC and EF across multiple land uses reveal that carbon emissions constitute over 70% of the region's total EF. Using downscaled climate projections from five general circulation models (GCMs) and three shared socioeconomic pathways (SSPs), future carbon trends are forecasted, showing a potential increase of 6.43–6.52 million tons by 2040. This amplifies the existing per capita ecological deficit of 1.49 global hectares. To mitigate this impact, the study designs 15 targeted carbon-reduction packages spanning energy, transport, industry, and household sectors. Concurrently, WSI analysis identifies critical water stress threatening Lake Urmia's ecosystem, prompting the development of seven additional water-use optimization packages to improve WECC. The coupling of these mitigation strategies within the integrated framework identifies the most effective combination—packages P4, P5, P8, P11–P14, P17, P20, and P21—improves the ecological stress index from 2.52 to 0.9 and reduces the WSI from 0.7 to 0.43 by 2040 under the most probable climate change scenario. This intervention successfully transitions the basin from a “critically overloaded” state to “moderate capacity,” demonstrating that integrated water and environmental management can restore regional sustainability even under climate change pressures. This combined approach offers a powerful tool for restoring ecological balance and provides a decision-support system that can be adapted for other basins facing comparable sustainability challenges, thereby enhancing WECC evaluation and policy development.