Combine olive oil, lemon juice, green onions, parsley, rosemary, thyme, salt, black pepper, and garlic powder in a small bowl. Set aside 1/4 cup of the marinade. Place salmon in a shallow dish and pour the remaining marinade over the top. Cover and refrigerate for 30 minutes. Remove the salmon and discard the used marinade.
½ cup olive oil, ¼ cup lemon juice, 4 green onions, thinly sliced, 1 tablespoon chopped fresh parsley, 1 teaspoon chopped fresh rosemary, 1 teaspoon chopped fresh thyme, ½ teaspoon salt, ⅛ teaspoon black pepper, ⅛ teaspoon garlic powder, 3 pounds salmon fillets