Question from a curious person: if goverment lost the ability to regulate factories how does society protect the local environment?

If a factory puts out cancer causing chemicals into the water and people are suffering because of it how do you deal with it without invoking a goverment in some capacity. If the goods are destined for foreign markets and the employees are paid well enough to not care about what happens to the locals it seems like the only recourse would be violence. If it came to violence then the company which likely has more money would likely win the altercation.

How would a libertarian society keep companies in check in regards to environmental concerns?