Dredging involves removal of accumulated bottom sediments in waterways to maintain adequate depth for navigation or to remove environmental contaminants. In the Great Lakes, navigational dredging may be required due to wind and wave action, which deposits sandy sediments in harbor mouths. In other instances, navigational dredging is conducted in response to soil erosion resulting from agriculture and development (Great Lakes Commission 1999). Although not as common as navigational dredging, environmental dredging is conducted to reduce the threat of contaminated sediments to ecological and recreational functions.

The need for sediment removal must be balanced against the critical need to protect the aquatic resources of Michigan's waters. Direct effects of dredging to the aquatic environment include destruction of spawning habitat, mortality of aquatic organisms, potential release of contaminated sediments, and destruction of near-shore habitat. Furthermore, dredging can re-suspend sediment, disrupt nesting birds, and result in the entrainment of aquatic organisms by hydraulic dredges (Great Lakes Commission 1999).

Conservation Needs to Address Dredging Threats:

Land, Water & Species Management

• Minimize dredging activity to the extent necessary to retain current navigation uses
  
  
• Develop and adhere to standards for timing of dredging activities to minimize adverse effects to spawning and migrating Great Lakes fish and nesting birds
  
  
• Discourage open water disposal of dredged materials
  
  
• Avoid freshwater mussel beds during dredging activities, or, if unavoidable, relocate beds to a suitable location

Law & Policy

• Require best management practices to limit escape of sediment (e.g., specialized dredge equipment and techniques)

Education & Awareness

• Encourage soil conservation practices such as vegetation cover, conservation tillage, and educational activities to reduce soil erosion and, therefore, the amount of dredging necessary over the long term
  
  
• Protect and promote naturally vegetated riparian corridors, thus reducing the need for rapid drainage

Capacity Building

• Provide financial incentives to private landowners to encourage soil conservation practices and conservation of naturally vegetated riparian corridors

Research, Surveys & Monitoring

• Continue to conduct research to determine timing and habitats used during spawning and migration for Great Lakes fish species to assist in minimizing adverse effects of dredging activities
  
  
• Conduct surveys to identify freshwater mussel beds that should be avoided during dredging activities
  
  
• Monitor freshwater mussel beds that have been relocated due to dredging activity to determine success of these mitigation efforts
  
  
• Develop and test best management practices to limit sediment escape during dredging