EXHIBIT 99.1 FIRST AMENDMENT TO AGREEMENT AND PLAN OF MERGER FIRST AMENDMENT TO AGREEMENT AND PLAN OF MERGER (this "First Amendment") dated as of December 2,1999, among EL PASO ENERGY CORPORATION, a Delaware corporation ("Parent"), EL PASO ENERGY...Agreement and Plan of Merger • January 14th, 2000 • El Paso Energy Corp/De • Natural gas transmission • Delaware
