Possible contamination of dredge spoils sites.Secondary impacts to aquatic and benthic organisms' metabolism and mortality.Tertiary impacts to avifauna which may prey upon contaminated aquatic organisms.Secondary impacts to marsh productivity from sedimentation.Secondary effects from water column contamination of uptake of heavy metals, DDT and other persistent organic toxins, via food chain uptake and subsequent concentrations of these toxins in higher organisms including humans.Short term increases in turbidity, which can affect aquatic species metabolism and interfere with spawning.

Release of toxic chemicals (including heavy metals and PCB) from bottom sediments into the water column.The activity of dredging can create the following principal impacts to the environment: In addition, dredge spoils may contain toxic chemicals that may have an adverse effect on the disposal area furthermore, the process of dredging often dislodges chemicals residing in benthic substrates and injects them into the water column.

Dredging can create disturbance to aquatic ecosystems, often with adverse impacts.

Hand gold dredges