Runoffs are a common problem after major fires, clogging rivers and streams and often killing fish.
What is killing fish, the researchers believe, is a water-borne fungus known as Aphanomyces invadans.
Environmentalists say the practice has destroyed 500 mountains, as well as covering villages with dust, polluting rivers and killing fish.
Those emissions combine in the atmosphere to produce smog, while also poisoning lakes and killing fish, especially in the Adirondacks.
Back in Caquetá, the church worker described how herbicides have run into rivers and streams, killing fish.
The pits are said to be still there, mixing chemicals with groundwater and killing fish and wildlife.
Water full of dyes and chemicals is often dumped directly into rivers, contaminating water and killing fish and other wildlife that millions of people depend on.
The July 2011 rupture fouled 70 miles of riverbank along the scenic river, killing fish and wildlife and prompting an extensive cleanup that lasted months.
It is thepeacetime bomb that goes off, from time to time, killing fish, killing men, gradually building up the level of radioactivity.
The E.P.A., aiming to prevent water intakes at power plants from killing fish and other aquatic life, was proposing regulations that the companies feared would require extensive renovations.
The World Wide Fund for Nature, a conservation group, said the heavy fuel oil also settled onto the seabed, surely destroying marine habitat and killing fish.
