Can u explain this in ur own words?
By 1987 it became clear that a great deal of pollution was coming from nonpoint sources. It was estimated that over 50 percent of the nation's remaining water pollution problems was coming from sources that are not easily identified, such as runoff from agricultural lands, construction sites, urban areas, and even forests.

Respuesta :

By 1987 it was becoming evident that 50 percent of the nations water pollution problems were coming from a number of hard to identify sources.