Fla. Stat. § 157.07

Whenever any public drain or auxiliary thereto has been constructed, is now in process of construction, or may hereafter be constructed by the board of county commissioners, under the provisions of any law now in force, or that may hereafter be enacted, and the actual cost of the construction of said drain or auxiliary shall have exceeded or may exceed the estimated cost thereof, said board of county commissioners shall assess against the lands benefited or to be benefited by said drain or auxiliary thereto, the difference between the estimated cost thereof and the actual cost thereof.