The same is true of those who live near any of a number of chemical- intensive manufacturing operations. Look upland and upwind, as well as upstream. Class I soil, the best for agriculture, is already rare enough. The land shed is just as precious as the water shed. If a chemical or waste spill contaminates the farm land you re counting on for a local food supply, all your preparations may be for naught.
Environmentalists know how to look upstream, upland and upwind.
Think of them as Contamination Trackers. Technologists know how to look at the machinery and find the things that might pop and must be shut off and re- started mindfully if at all.