Climate change and unsustainable resource exploitation can adversely affect ecosystem functioning and biodiversity. Vegetation degradation and freshwater depletion are important indicators of environmental change and inadequate resource management. Remote sensing provides an effective means of monitoring vegetation and surface water dynamics. This study investigated temporal variations in vegetation cover and surface water extent in the Qazvin Plain Salt Marsh (QPSM), Iran, from 2017 to 2021. Landsat 8 imagery was processed using Google Earth Engine (GEE) to calculate the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI). The resulting datasets were analyzed in a Geographic Information System (GIS) to estimate land-cover classes and surface water extent. Vegetation was classified into five categories using NDVI thresholds. The results revealed substantial interannual variability in vegetation cover and surface water extent rather than a consistent declining trend. Estimated surface water area increased from approximately 28,000 ha in 2017 to 42,000 ha in 2018, declined to 15,000 ha in 2019, increased to 27,000 ha in 2020, and decreased to 22,000 ha in 2021. The estimated water area in 2021 was approximately 21.4% lower than in 2017. NDVI-based land-cover estimates also varied considerably among years, particularly for fallow land and grassland. These fluctuations indicate substantial short-term changes in vegetation conditions and surface water extent. However, the short observation period and threshold-based classification approach limit the interpretation of these changes. Therefore, the findings should be interpreted cautiously, as they do not independently establish a persistent long-term trend in environmental degradation.