Iowa Code § 161F.2
The board of supervisors of any county shall have jurisdiction, power and authority at any regular, special or adjourned session to establish, subject to the provisions of this chapter, districts having for their purpose soil conservation and the control of flood waters and to cause to be constructed as hereinafter provided, such improvements and facilities as shall be deemed essential for the accomplishment of the purpose of soil conservation and flood control. Such board shall also have jurisdiction, power and authority at any regular, special or adjourned session to establish, in the same manner that the districts hereinabove referred to are established, districts having for their purpose soil conservation in mining areas within the county, and provide that anyone engaged in removing the surface soil over any bed or strata of coal in such district for the purpose of obtaining such coal shall replace the surface soil as nearly as practicable to its original position, and provide that, upon abandonment of such removal operation, all surface soil shall be so replaced. This section shall apply only to surface soil so removed after July 4, 1949, and then only if it is essential for the accomplishment of the purpose of soil conservation and flood control within the purview of this chapter.
Iowa Code § 161F.2