Iowa Code § 468.144
When such agreement is filed, the auditor shall record it in the drainage record. The board shall at a regular, special, or adjourned session thereafter locate and establish a drainage district and locate the ditches, drains, settling basins, and watercourses thereof as provided in said agreement, and enter of record an order accordingly. The board thereafter shall carry out the object, purpose, and intent of such agreement and cause to be completed and constructed the said improvement and shall retain jurisdiction of the same as fully as in districts established in any other manner. It shall cause to be levied upon and against the lands of such district, the drainage taxes and assessments according to said agreement and when collected said taxes and assessments shall constitute the drainage funds of said district to be applied upon order of the board as in said agreement provided.
Iowa Code § 468.144
89 Acts, ch 126, §2