For purposes of this article, service territory of a local publicly owned electric utility means within the boundaries of its service territory as it existed on December 20, 1995, or within the boundaries specified in an applicable service territory boundary agreement entered into pursuant to Article 1 (commencing with Section 8101) of Division 4, or any other provision of law, between an electrical corporation and the affected local publicly owned electric utility, or within the boundaries specified in an applicable service territory boundary agreement between one local publicly owned electric utility and another local publicly owned electric utility. Furthermore, for purposes of this article, the boundaries of the Merced Irrigation District shall be as those boundaries existed on December 20, 1995, together with the territory of Castle Air Force Base, which was located outside of the district on that date.