In response to growing concerns over increased air and water pollution, by the early 1970s the United States Congress had begun enacting a series of statutes that continue to shape environmental law today, more than four decades later.  The laws authorize federal agencies to regulate air quality, water quality, the management and disposal of solid and hazardous wastes; and to protect threatened or endangered species of plants and animals. Congress, in enacting these environmental laws, knew that it was imposing significant compliance costs on regulated sectors of the economy.