I have seen several petitions in the past three months that have resulted in action taken by the Federal Regulators, guess what, Congressional action was not involved nor sought.  Well written petitions and comments can have an effect on rulemaking, I should know as I had to write and evaluate regulations and comments.  Congress passes laws but it is the Executive Branch that writes the regulations to conform with the enacted Public Law.  Often in determining Congressional Intent on a Public Law , it is necessary to go into the hearing records for a particular law.  The EIS is an action taken by any agency when they determine that an EIS is needed or has been requested.  It is all done in accordance with the requirements as stipulated by National Environmental Protection Act (NEPA).