Dredged Mud Used to Restore Saltmarsh at Lymington Harbour

Dredged mud from Lymington Harbour on the south coast is being utilized in an innovative scheme to restore the eroding saltmarsh surrounding the area. The project aims to protect the local economy and wildlife, with hopes that this remarkable recovery of natural habitat could be replicated in coastal areas at risk from rising sea levels.

Protecting Lymington Harbour

Lymington Harbour, located in Hampshire, is a crucial hub with a ferry link to the Isle of Wight, 1,600 leisure moorings, and around 20,000 visiting yachts annually. The harbour plays a significant role in the local economy, generating millions of pounds each year. However, the saltmarsh that protects the harbor is facing erosion at a rate of two to three meters annually due to rising sea levels and increased storminess attributed to climate change.

Efforts to combat erosion have involved building rocky breakwaters and depositing dredged mud in front of the saltmarsh. Now, a partnership led by Lymington Harbour Commissioners and Land & Water Group is experimenting with new methods to place dredged sediment at a suitable height for plant recolonization and habitat restoration.

Importance of Saltmarshes

Ryan Willegers, chief executive of Lymington Harbour Commissioners, highlighted the decline of the saltmarsh since the early 20th century, emphasizing the crucial role it plays in protecting the harbor. James Maclean, chief executive of Land & Water, stressed that saltmarshes are not only essential for coastal defenses but also support a significant portion of marine species found in inshore waters.

With around 20 million tonnes of nutrient-rich sediment dredged from UK harbors each year being disposed of offshore, the project aims to utilize this sediment to restore saltmarshes and prevent the collapse of marine ecosystems due to rising sea levels.

Trialling New Technologies

As part of the trial funded by the Environment Agency, the team is utilizing innovative technology inspired by Victorian steam drag boxes. This technology involves a “giant scoopy sled” attached to a 28-tonne excavator with a hydraulic winch, allowing for precise placement of dredged mud to regenerate habitat within the saltmarsh.

During the initial year of the trial in 2024, approximately 800 cubic meters of mud were placed at the required height to facilitate habitat regeneration in the least exposed area of the saltmarsh.

The project, supported by the Crown Estate, aims to not only protect Lymington Harbour but also serve as a model for coastal conservation efforts nationwide. By integrating dredged mud into saltmarsh restoration, the initiative seeks to safeguard both the local economy and the diverse wildlife that depend on these vital coastal ecosystems.