WILLIAMS PARTNERS L.P. And THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A. Trustee FOURTH SUPPLEMENTAL INDENTURE Dated as of November 15, 2013 To INDENTURE Dated as of November 9, 2010 $600,000,000 4.500% Senior Notes due 2023 $400,000,000 5.800%...