Manasarovar or Lake Manas situated at an altitude of 4, 590 m / 15, 060 ft., is a glacier melt freshwater lake. It is the holiest pilgrimage site for the Hindus, Buddhists, Jains and the animistic Bonpos (a religion predating Buddhism in Tibet). Though often touted as the world's highest freshwater lake, in actuality the credit goes to Lake Pumoyong also located in Tibet.
Mt. Gurla Mandhata can be seen on the bank of the lake.
The blue hue is moonlight and not any Photoshop trickery.