A three-decade lake dataset on the Mongolian plateau tracking water area and quality dynamics (1990-2020)

Lakes on the Mongolian Plateau (MP) are vital freshwater and ecological resources, yet comprehensive long-term records of their area and water quality dynamics have been lacking. To fill this gap, we developed the Mongolian Plateau Lake Dataset (MPLD)-the first open-access, spatially explicit dataset providing annual records (1990-2020) of lake extent and three water quality indicators (Secchi Disk Depth, Total Suspended Matter, and Forel-Ule Index) for 1,161 lakes ( > 1 km², including artificial reservoirs). Built from over 56,000 Landsat scenes processed via Google Earth Engine, the dataset reveals a pattern of initial lake shrinkage followed by partial recovery, with total lake area reaching 19,592.78 km² by 2020. By that year, 71.83% of lakes were classified as eutrophic (FUI ≥ 10).The data show strong spatiotemporal heterogeneity: western and northern lakes expanded and cleared, while eastern and central Inner Mongolia saw contraction and water quality decline. The MPLD provides critical support for water resource management across the MP and serves as a valuable reference for global studies on climate change and dryland dynamics.