If the secretary of state finds the petition to be sufficient as to form and the number and qualifications of the petitioners, he or she shall prepare a certified copy of the petition and transmit the same to the chief engineer within five (5) days from the date of his or her determination of sufficiency. Upon receipt of such certified copy the chief engineer shall institute an investigation of the proposed district, its territory and purposes, and shall within ninety (90) days after receipt of said copy transmit a written report of his or her findings on the petition together with his or her written approval or disapproval of the petition, to the secretary of state and the acting chairman of the steering committee named in the petition.

The chief engineer shall approve such petition if he or she finds and discloses by his or her report:

(1) That the boundary of any proposed district as defined is limited to but, as far as practicable, includes all quarter-quarter-quarter sections (square ten-acre tracts) of which more than one-half is subject to injury and damage from the overflow of some watercourse or watercourses, naming or describing it or them, or to include all of any such quarter-quarter-quarter sections which contain a portion of the channel of the named or described watercourse or watercourses, or includes, as far as practicable, all quarter-quarter-quarter sections which are subject to injury and damage from standing water not resulting from the overflow of some watercourse;

(2) that the downstream limit of any proposed district is established with due regard to the location of highways and railroads and the location and character of existing works of improvement, the boundaries of any organized levee, drainage, irrigation and watershed districts, and the physical characteristics of and the probable relative effect of the operation of the proposed district upon any flood plain area common to both the stream or watercourse and any other stream or watercourse;

(3) that the improvement of the channel of such watercourse or watercourses, the construction and maintenance of levees, drains or other works, including detention dams and reservoirs, are necessary to prevent such overflow;

(4) that such improvement or works will be conducive to the public health, convenience or welfare;

(5) that the proposed drainage district would not include lands in any existing drainage or watershed district;

(6) that the map attached to the petition and the description of lands proposed to be included in the district are adequate and correct. The chief engineer, in his or her report, may make minor corrections with respect to the map or the description of lands proposed to be included in the district to make such map and description of lands conform to the map previously prepared in consultation with the chief engineer, and such corrections shall thereupon become a part of the petition and be deemed effective without a recirculation of the corrected petition among the landowners. If the chief engineer shall approve such petition, he or she shall transmit a certified copy of his or her report to the secretary of state and to the chairman of the steering committee of the district.