MSU Extension Michigan Sea Grant

Summary of Research Related to the Potential Physical and Biological Impacts of Dredging to Channelize the Grand River

A Working Paper, May 9 version with appendices added November 22, 2019

The Grand River Waterway proposal is not a typical harbor dredging project, but rather a river channelization project that would remove roughly 50 acres of shallow habitat through dredging portions of the Grand River in Kent and Ottawa counties. The project seeks to create a 7-foot deep channel through a 22.5-mile stretch of the Grand River between Grand Rapids and Bass River State Recreation Area near Eastmanville.

The Grand River Waterway economic impact study stated that river channelization via dredging will “help return the river to its natural state” and that “increased recreational opportunities and improved water quality may generate up to 49,000 net new visitor days annually … and an annual net new economic impact of up to $5.7 million.” Research suggests that dredging will not improve water quality. A more likely scenario is reduced water quality, increased erosion of private and public land, increased deposition of sand and silt in certain areas, and harm to fish and wildlife populations. This paper deals specifically with physical and biological impacts, but it is important to note that these have economic implications, as well.

Appendices to Summary of Research Related to the Potential Physical and Biological Impacts of Dredging to Channelize the Grand River

Appendices published November 22, 2019

Appendix I – 2019 Mussel Sampling in Ottawa County Waters of the Grand River
Appendix II – Response to Critique by Grand River Waterway’s Consultants
Appendix III – List of Groups That Oppose and Support Grand River Waterway

These appendices provide an update to the May 9, 2019, MSU Extension working paper based on subsequent sampling conducted on the Grand River in Ottawa County and a critique of the working paper by GZA consultants working on behalf of the Grand River Waterway organization. Sampling conducted in August and September 2019 revealed shallow gravel habitat, large woody debris, and training walls in the path of proposed dredging in Ottawa County. A diverse mussel community was also discovered outside of the proposed channel in Ottawa County waters of the project area. Studies conducted to date cannot rule out the possibility of impacts to this site and other off-channel habitats that could result from changes in current velocity, sedimentation, and erosion post-dredging. Although the magnitude of negative impacts is uncertain at this time, published scientific literature from around the world supports the general conclusion that dredging to channelize a river harms benthic macro-invertebrates, freshwater mussels, and fish. This is supported by the Michigan Department of Natural Resources’ Wildlife Action Plan and Grand River Assessment, which both list channelization as a serious threat to large river ecosystems.