I agree, there would be little impact on the environment forest and animal wise, at least not worthy of mention.

What the natives worry about, or at least exaggerate, is the potential impact from pollution. Namely chromite ore blowing off transporting truck or railway cars. There is also potential impact from tailings. Note that Noront at the Eagle mine intends to return the tailings underground to act as fill for the tunnels from which the ore is excavated.
Pollution could mean degraded ground water and fishing grounds.
Pollution is varaiable and highly dependent on the operations type and methods taken to prevent or limit. Noront seems to appear to be very responsible and natives very inflamatory.

Therefore I agree that there is more noise made about the subject then is warranted. Unfortunately I am no expert so my opinion means squat.