Monitoring water bodies such as lakes is expensive, but remote sensing made it cost-effective. The extensive anthropogenic activities negatively impact the water lakes everywhere. Moreover, the Egyptian coastal lakes are not an exception. This paper investigates changes in land use/land cover and detects coastal changes of Buullus Lake, ranked to be the second-largest Egyptian northern Mediterranean coastal lake, using Remote Sensing and Geographic Information Systems (GIS) techniques. Multitemporal Landsat satellite images from 1984 to 2019 have been collected and processed where Landsat and Sentinel-2A images for 2019 have been used for comparison purposes. In addition field visits have been conducted to verify the obtained results. The maximum likelihood supervised classification approach was shown to be more accurate in monitoring changes in the Lake's water bodies. Classes of the supervised classification included eight classes; seawater, lake water, floating vegetation, sand, urban, agricultural areas, fish farms, and drainage canals. Analysis of the satellite data indicated that: between 1984 and 2019, the lake's water bodies and floating vegetation area were reduced by 16 % and 52 %, respectively. While agricultural lands increased by (648 km2). In addition, there has been a significant growth in the area of fish farms (290 km2). The resulted updated spatiotemporal maps and extracted water features assist decision-makers in taking the necessary steps to stop or minimize anthropogenic activities. These steps will help to restore or maintain the lake to host the government planned activities to achieve the Sustainable Development Goals (SDGs) on the lake level.