The location of Sarawak State in the equatorial region makes it an area of high rainfall. For this reason, hydroelectric power plants have been built in several catchments in Sarawak, especially in the Kapit area. This needs to be harnessed to improve the economy and social living standards of the people of Sarawak in particular. This paper presents the land cover change by analyzing the stratification change for 30 years (1985-2018) at Bakun Dam, Sarawak. This study uses Landsat 5 and Landsat 8 satellite data. Both data have to go through pre-processing such as geometric, radiometric, and atmospheric corrections. In this study, Normalized Water Difference Index (NDWI) is used to classify water areas, built human areas, and vegetation areas. Overlay analysis was applied to identify areas that had changed over the 30 years in the study area. The results showed the greatest changes from vegetation areas to water bodies for 30 years. The results showed that the most affected land cover was forest cover with a reduction of 740 km², which shifted mainly to water bodies with 669.9 km² and human development with an area of 68.7 km². The study area is less populated and anthropogenic influences are rather low, but deforestation is observed in the upper river basin. These events would change the hydrological behavior of these catchments in the future. Land cover mapping is very important to provide information to those responsible for planning sustainable development. In addition, land cover maps are important for land use planning and land use regulation to avoid land-use conflicts.