This is a great example of how we don't weigh externalities in GDP, why we should, and why we need market based solutions to those externalities. For example, a cap on river pollutants so low the river and wildlife can't be poisoned and each company has to buy rights from the limited pool, or if too expensive, find ways to limit their pollutants.

I once read (from Milton Friedman IIRC) that some european countries passed a law to limit river pollution by requiring companies to have their river water intakes downstream of their outflows. Supposedly this made a huge difference in the amount of pollutants they dumped in the river. That is a simple but limited way of imposing the externality costs on the persons who inflict the damage.