Whenever a petition, verified by one or more persons and signed by not less than 10 percent of the qualified electors residing in the territory which is proposed to be formed into a municipal park improvement district, setting forth a general description of the improvement or work to be acquired or constructed and a general description of the exterior boundaries of such proposed district, shall have been filed in the office of the clerk of the legislative body of the city, and the genuineness of the signatures shall have been certified to by the city clerk, the legislative body may adopt an ordinance declaring its intention to call an election in the proposed district for the purpose of submitting to the qualified electors of the district the proposition of authorizing the issuance and sale of bonds of the district in the manner and for the purpose set forth in the ordinance of intention. The legislative body shall have power to change or modify the boundaries of the district and the nature, character or extent of the proposed public improvement or work.