The school was the first secondary school in the South Island to win a silver award, which thrilled the organisers and Otago Girls High School Environment Committee chairman Douglas Black.
"It's a big achievement," Mr Black said.
"If you're going for a silver award, it has to be a team effort. The environmental message needs to spread throughout the whole school."
Mr Black said the school had worked hard to build environmental awareness among staff and pupils, and had developed an environmental care code.
Task forces had also been established to look at the school's waste and recycling, energy use and carbon footprint, and landscape.
The school is one of 39 taking part in the EnviroSchools programme and one of six which received awards at the ceremony.
Kaikorai Primary School and Hawea Flat School also won silver awards, and Portobello School, Macandrew Bay School and Waitati School won bronze awards.
Otago EnviroSchools assistant regional co-ordinator Katherine Dixon said five main principles guided schools in the programme.
They were derived from emerging understandings about how environment, ecology, education, society and culture each contributed to creating a sustainable world, she said.
Schools are encouraged to develop these principles and continually check for signs they are growing and visible.
Mr Black said Otago Girls High School would now work towards the challenging task of earning a gold award.
"That will take another two years, at least."
