The appraisers shall forthwith proceed to the assessment of damages and shall make written report of the damages to the board of supervisors. [SS15, §1527-r2; C24, 27, 31, 35, 39, § 4613; C46, 50, §306.54; C54, 58, 62, 66, §306.25; C71, 73, 75, 77, 79, 81, §306.31 ] 99 Acts, ch 171, §31, 42 Referred to in §306.19 , 306.27 , 331.304