Increase in levels of suspended sediment during maintenance dredging operations
This could potentially affect the SPAs/Ramsar by remobilising and redistributing contaminated sediments within the estuary and by affecting populations of small fish which are a food source for a number of waterfowl. The provision of sediment samples is a requirement of all new dredging applications and samples must be provided once every two years for ongoing maintenance dredging operations.
The PLA has developed guidelines on the number of samples required which is dependent upon the quantity of sediment to be dredged. This provides a mechanism for modifying or preventing dredging if the sediments are significantly contaminated.
In some areas of the estuary, contaminants are present at deeper levels within the sediments, and a buffer layer is maintained to prevent dredging of the contaminated sediments. However, it is understood that in no locations has contamination been identified which precludes dredging. It is therefore considered unlikely that maintenance dredging has to date had an adverse effect on the integrity of the European Marine Sites through remobilisation of contaminated sediments. Furthermore, assuming the existing Maintenance Dredging Framework testing regime stays in place, it is unlikely that an impact would be allowed to occur in the future.