Dredging these smaller waterways can produce four types of harm that must be weighed when considering the benefits to recreational boaters.

     1. Environmental harms

          * The soil deposits in any water-body have a certain predisposed composition. Dredging alters this composition. Due to this alteration, the existing habitat of creatures and organisms that depend on the original composition of the soil may die out, and aquatic ecosystems may be disrupted.

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          * The turbidness (the stirring up and possible suspension of sediment) of the soil under the water also changes because of this alteration in underwater soil composition. This poses problems by way of creation of newer and harmful organisms, transferring of unwanted organisms to other parts in the water-body leading to a wider spread of contamination and organic processes by way of release of extra and unwanted nutrients. There may be interference with the spawning of marine life. The turbidness also causes the already existing contaminants to spread further into the water-body which also affects the marine environment adversely.

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          * Harmful secondary impacts to marsh productivity and tertiary impacts to marine life may occur.

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          * There may be unacceptable environmental impacts on upstream waterway ecology – such as salinity penetrating further inland.

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          * Possible contamination of dredge spoil sites (the sites where the dredged materials are deposited). The nature of dredging operations and possible environmental impacts cause the industry to be closely regulated. The U.S. Clean Water Act requires that any discharge of dredged or fill materials into waterways, including wetlands, is prohibited unless authorized by a permit issued by the Army Corps of Engineers. This process focuses solely on potential negative impacts to the environment. In addition, the U.S. Environmental Protection Agency provides oversight and authorization for the disposal of dredged materials (National Ocean Service, 2017).

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A study in West Virginia reported:

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Dredging has both short and long-term effects on the natural and human environment. Some or all of the following may occur during or after dredging operations: • increased water flows downstream and increased flooding, • disturbance caused by vehicle and equipment access, • destruction of stream bank and aquatic vegetation, • disruption of the aesthetic values of the stream corridor, • removal, release, or rearrangement of sediments, • reduction of water quality, • remobilization of contaminants, • increased turbidity, • lowered water tables, • increased erosion and sedimentation, • alteration of hydrology, • alteration of hydraulics (current patterns and flow), • increased bank instability and erosion, • alteration of  fish habitat, • alteration of fish spawning habitat, • alteration of benthic (the flora and fauna found at the bottom of a body of water or in the bottom sediment) habitat, • disruption or removal of benthic communities, • reduction in height of high frequency, low- level flood events over the short term unless it is properly maintained, and • false sense of security following dredging (West Virginia Conservation Agency, 2017).

     2. ​High costs

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          * The costs associated with studies required to get a permit are very expensive.

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          * The capital costs of a dredging operation are very expensive.

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          * Benefits gained in the short term are usually soon lost through siltation and shifting banks. This means that once a waterway is dredged, it will need to be dredged periodically in the future – thus adding more cost. “In North Carolina there are two types of federally authorized channels or inlets: deep draft inlets (which have more than a 15-foot depth) and shallow draft inlets (which have a 15-foot depth or less). The two deep draft inlets in North Carolina are Wilmington Harbor and Morehead City. Historically, deep draft inlets have not been an issue in North Carolina. It is shallow draft inlets that are a concern due to their tendency to shoal (development of sand or other material that rises from a body of water to near the surface; these may impact navigability of the water rapidly” (Lesher, 2015).

     3. Alteration of community ambience – the introduction of more and larger boats can change a small, quiet community into a more bustling, commercial community. Smaller water enjoyment activities (paddleboards, kayaks, canoes, etc.) are more difficult in areas with more boat activity especially if they are large and fast boats (KaranC, 2016; Maritime Safety Queensland, 2017).

     4. Harmful unintended consequences. It is not always possible to anticipate consequences of dredging as the state of Florida learned in one of its dredging programs.

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Florida’s coastal population growth and urban development have been driven in part by the creation of the Intracoastal Waterway System to facilitate vessel navigation…Canal systems, originally dredged to create land for homes, have become de facto transportation systems linking tens of thousands of residential boat docks to the ICW and to deeper water in the Atlantic Ocean and Gulf of Mexico. Naturally occurring deeper channels, dredged waterways, and canal systems are also preferred by manatees as migratory routes and travel corridors to feeding areas and, in the case of residential canal systems, as “safe havens” and important sources of freshwater discharge” (Bayside Cape Coral, 2017).   

These natural and human created conditions contribute to a greater chance of collisions between manatees and boats – a significant cause of manatee deaths in Florida…In addition, the alteration of wetlands by dredge and fill operations, channelization of rivers and streams, and other changes to freshwater flow also threaten the habitat that manatees rely on for survival (Manatee Awareness and Protection Program, 2007). The Florida manatees have lived in the state’s waters for about 12,000 years, while their ancestors were here for over one and a half million years. Manatees are a federally listed threatened species and are protected by the State of Florida (Bayside Cape Coral, 2017).