At the time and place of the public hearing, the legislative authority must consider the petition. The legislative authority may receive any evidence it deems material that supports or opposes the formation of the district, including the inclusion or exclusion of land. Unless an amended petition satisfying the requirements of RCW 36.145.020 is approved in accordance with the requirements of this chapter, no land outside the boundaries described in the petition may be included within the proposed district. No land inside the boundaries of an approved petition may be removed from the district unless an amended petition satisfying the requirements of RCW 36.145.020 is approved in accordance with the requirements of this chapter.