There are two firms on a lake that both rely on clean water from the lake to raise trout. They release their wastewater, which contains fish droppings, back into the lake. With these two firms on this lake, they can currently use the lake water without treating it because contaminant levels remain low enough. A third firm is thinking about raising trout on the lake as well. If it does, then the contaminant levels from the wastewater of the three firms combined will make it so that all three firms have to pay to install water treatment systems to continue raising trout. For the efficient outcome to occur, the third firm would have to consider the costs of wastewater treatment for _____________________ when it decides whether to build a facility on the lake.