Dear Rahul,

You can check the top colleges for M.tech for environmental engineering in Karnataka below

National Institute of Technology Karnataka Surathkal

Manipal Institute of Technology, Manipal

Indian Institute of Science, Bangalore

PES University, Bangalore

BMS College of Engineering, Bangalore

JSS Science and Technology University, Mysuru

To check the complete list you can refer below link

https://engineering.careers360.com/colleges/list-of-engineering-colleges-in-India?f%5B0%5D=sm_college_course_level%3APG&f%5B1%5D=sm_college_degree%3AM.E%20/Mtech.&f%5B2%5D=sm_college_state%3AKarnataka&f%5B3%5D=sm_course_offered%3AEnvironmental%20Engineering

Good Luck!!