“Local agency” also means any entity or agency created pursuant to Article 1 (commencing with Section 6500) of Chapter 5 of Division 7 of Title 1 for the purpose of acquiring, constructing, maintaining, or operating systems, plants, buildings, works or other facilities or property for the purposes of disposal, treatment, or conversion to energy and reusable materials of solid waste. Any proposition submitted to an election held within such local agency for the purpose of authorizing bonds shall be deemed adopted if it receives the affirmative vote of a majority of all the voters voting on the proposition. Such an election shall be held within the combined territory of all local agencies which, pursuant to such Article 1, have jointly created such entity or agency.