If, after the formation of a district, the addition of properties to be maintained as open areas by the existing district is proposed, the legislative body shall adopt a resolution declaring its intention that the cost of maintaining the additional open areas shall be borne by the existing district. It shall fix a time and place for a hearing on the resolution, at which hearing any and all persons having any objections to the things proposed to be done may appear and be heard. The resolution shall contain the statement of the estimated annual cost of maintaining the additional open areas. If new or increased assessments are proposed, the legislative body shall comply with the notice, protest, and hearing procedures pursuant to Section 53753.