70 ILCS 605/3-13
The temporary commissioners shall examine the area proposed to be included in the district and the land upon which any portion of the drainage system is proposed to be constructed. They shall not be confined in their deliberations to the system of drainage proposed in the petition, but may consider such alterations or modifications of the same as they believe will best drain or protect the lands in the proposed district with the least damage and greatest benefit to all lands affected. No system of drainage shall be considered or proposed by the temporary commissioners unless such system shall at least provide a main outlet of ample capacity to drain the lands in the proposed district, but this limitation shall not apply to any district proposed to be organized for the sole purpose of protecting lands against overflow.
70 ILCS 605/3-13