Any 2 or more adjoining drainage districts may by contract establish joint systems of drains, levees, pumping plants or other works and provide for the construction, reconstruction, repair, maintenance and operation thereof. For the purposes of this Article, districts shall be considered as adjoining when any portion of their boundaries are contiguous or overlap. When the joint system is established by more than two districts it shall not be necessary for each of the districts to adjoin each of the other districts but it shall be sufficient if each district adjoins one of the other districts.
70 ILCS 605/11-14