Subdistricts of a soil and water conservation district may be formed as provided in this chapter for the purposes of carrying out watershed protection and flood prevention programs within the subdistrict but shall not be formed solely for the purpose of establishing or taking over the operation of an existing drainage district.
Iowa Code § 161A.13
86 Acts, ch 1238, §61; 87 Acts, ch 23, §22; 89 Acts, ch 83, §58