The benefits of dredging are:
1. improves existing water features for better drainage, navigability, and commercial use
2. important for constructing dams, dikes, and other controls for streams and shorelines
3. helps in recovering valuable mineral deposits or marine life having commercial value

The demerits of dredging are related to its severe environmental impact, for example:
1. it can disturb marine sediments, leading to both short- and long-term water pollution
2. it can destroy important seabed ecosystems
3. it can release legacy human-sourced toxins captured in the sediment
All the above impacts can significantly hurt marine wildlife populations, contaminate sources of drinking water and interrupt economic activities such as fishing.