Michigan Compiled Laws, Chapter 211. Taxation of Real and Personal Property § 211.7g

Sec. 7g. The value of a seawall, jetty, groin, dike, or other structure whose primary purpose is to prevent or control erosion or prevent or control inundation or flooding on property affected by waters or levels of the Great Lakes or their connecting waters and tributaries as affected by levels of the Great Lakes is exempt from taxation. The department of natural resources shall, when requested by the owner or the assessor, determine if such seawall, jetty, groin, dike, or other structure has as its primary purpose the prevention or control of erosion.

That portion of structures which are modified or designed to provide benefits other than erosion control or flood prevention are not exempt from assessment for property tax.