This study was done on 86 images from Landsat 5 and 8 from the years 1990 to 2023, and emphasized the spatial change of Birendra Lake. The Otsu method was used on the normalized difference water index (NDWI), modified normalized difference water index 1 and 2 (MNDWI), and automated water extraction index (AWEI) for this study. The area of Birendra Glacial Lake area grew significantly between 1990 and 2023 (94,500 m2 to 222,300 m2) because of climate change. The mean annual temperature was increasing at a rate of 0.024 °C every year and the total precipitation was increasing at a rate of 14.531 mm every year. The increase in the snow depth from 1999 to 2007 was observed and the snow cover from 2011 to 2020 was also found to be increasing. The lake area was validated by using the KNN method. The lake area from Google Earth was found to be 246,060 m2 on 10/07/2013 while from the Otsu method, the lake area for the date 10/24/2013 was 222300 m2. A relative error of 10.69% was found when the result obtained from the Otsu method was compared with the result from the KNN method. Furthermore, a comprehensive study including a field survey of the lake is suggested for more accuracy.