BELFAST, Maine (AP) A large, land-based salmon farming operation in Maine has obtained a key approval it needed to move forward, but opposition to the project remains.

Nordic Aquafarms wants to build a $500 million, 55-acre salmon farm in Belfast. The company announced earlier this week that is has received an Army Corp of Engineers permit, which is the final permit it needs.

Local conservationists are still challenging the salmon farm in court, Maine Public reported. They have concerns about how the project would discharge waste water. Environmentalists have also raised concerns about the size of the project and its other potential impacts on the community.

Nordic Aquafarms spokesperson Marianne Naess said in a statement that the company is ready to move into the final stages of engineering and construction planning for the facility. The company has said the facility would produce tens of millions of pounds of salmon per year.

Nordic is based in Norway and operates similar operations in Europe.