When the owners of lands lying outside of a district but within the same natural drainage basin or involved in the same system of drainage as the lands within the district, desire to have their lands annexed to the district, they may so petition the court. The petition must meet the proportional requirements of Section 3--3 as to signers and shall include a description of the lands proposed to be annexed and the names of the owners, when known.
70 ILCS 605/8-4