Position statement and evaluation guidelines
From the document:
A habitat enhancement structure (marine habitat enhancement structure) is a submerged structure deliberately constructed or placed on the seabed to emulate some functions of a natural reef such as protecting, regenerating, concentrating and/or enhancing populations of living marine resources.
Objectives of a habitat enhancement structure may also include the protection, restoration and regeneration of aquatic habitats and the promotion of research, recreational opportunities and educational use of the area.