Mich. Comp. Laws § 67.19: Bridges, streets, and highways; principles of tax apportionment.

Sec. 19.

Assessments made under section 18 upon exempt public lands may be paid from the general highway fund, or may be apportioned to the other assessable lots, at the option of the council. If because of the shape or size of any lot an assessment thereon in proportion to its frontage would be unjust and disproportionate to the assessment upon other lots, the council making the assessment may assess the lot for such number of feet frontage as in their opinion is just.