From Wikipedia;
” On July 9, 1970, citing rising concerns over environmental protection and conservation, President Richard Nixon transmitted Reorganization Plan No. 3 to the United States Congress by executive order, creating the EPA as a single, independent agency from a number of smaller arms of different federal agencies. Prior to the establishment of the EPA, the federal government was not structured to comprehensively regulate environmental pollutants.”
Thanks for you post, I see it was an EO that started it.