The award was presented at IrrigationNZ's recent biennial conference in Timaru.
The company's entry featured a comprehensive programme of environmental management which had been developed during the last six years.
The company's scheme irrigates 10,000ha, with work under way on stage two.
Environmental stewardship was part of everything the company did, NOIC chairman Leigh Hamilton said in a statement.
"It starts with our culture and values and is a central part of all our day-to-day operations, and has been so since the very start of the company."
Environmental sustainability was not just something that happened on its own.
The company has invested significant time, money and effort into developing environmentally sound farm plans and improving environmental performance right across its scheme, Mr Hamilton said.
He thanked the Otago Regional Council and farm planning consultant Ian Brown for their ongoing support, while also recognising the commitment of the company's shareholders to environmental improvement.
The company intended using the $2500 prizemoney to help fund an environmental project within the local community such as a biodiversity and water quality enhancement project in the Waiareka Valley.