Complex sentence: Shortly after the act was signed into law, President Richard Nixon expanded the CEQ's mandate by executive order, directing it to issue guidelines to federal agencies for the proper preparation of an EIS and to assemble and coordinate federal programs related to environmental quality.
Split into simpler sentences: Shortly after the act was signed into law, President Richard Nixon expanded the CEQ's mandate by executive order. He directed the CEQ to issue guidelines to federal agencies for the proper preparation of an EIS and to assemble and coordinate federal programs related to environmental quality.