On June 25, 2013, President Obama issued a Presidential Memorandum directing the Environmental Protection Agency (EPA) to work expeditiously to complete greenhouse gas (GHG) standards for the power sector. The agency is using its authority under section 111(d) of the Clean Air Act (CAA) to issue emission guidelines to address GHG emissions from existing power plants. The Presidential Memorandum directs the EPA to issue proposed GHG guidelines for existing power plants by no later than June 1, 2014, and issue final guidelines by no later than June 1, 2015. In addition, the Presidential Memorandum directs the EPA to, in the guidelines, require States to submit to EPA the implementation plans required under section 111(d) of the CAA by no later than June 30, 2016. On June 18, 2014, the EPA proposed emission guidelines for States to follow in developing plans to address GHG emissions from existing fossil fuel-fired electrical generating units (EGU), using its authority under CAA 111(d). On November 4, 2014, the EPA published a supplemental proposal to address GHG emissions from existing fossil fuel-fired EGU on tribal lands and in U.S. territories. On August 3, 2015, the EPA Administrator signed the final Clean Power Plan rule.