Over the past 160 years, rocks and boulders were removed from the river bottom and used as fill for construction along the river or in the foundations of many buildings within the city. Using natural boulders, rock and cobble to construct the proposed improvements will contribute to the aquatic diversity of the Grand River. The pocket water, micro-eddies, seams, fast water and slow water created by the use of natural boulder and alluvium all contribute to improved oxygenation, macroinvertebrate habitat, and overall health of a river. These features also provide healthy structure and habitat for a variety of fish and wildlife species.