hi,

ugc net score is used to recruitment for lecturers in college and as well as research fellowship program, see if you want to come in teaching career or interested to do phd then you should appear in ugc net, however m.tech in environment engineering has also various job available in many industry and manufacturing company. however try to do m.tech from a tier 1 institute, like iits, nits, vit vellore, bits etc.