The primary source for all hydrographic information should be UK Hydrographic Office (UKHO) charts.

All areas within the Authority’s jurisdiction are regularly surveyed and the data submitted to UKHO.

Mini plots are featured on this page for area that are regularly dredged by the Authority.  These are plots with a reduced number of soundings to highlight areas of significant depths that should be considered when using the Deep-Water Channel and Harwich harbour.

Navigable depths have been assessed based on acoustic measurements (echo sounder MBES and SBES). In Harwich Harbour, which is subject to fluid mud, data is based additionally on yield stress values (which are provided as single point values).

Mariners are advised the latest hydrographic surveys, including those that show depths in the Harwich Deep Water Channel – which are published as follows:

Harwich Deep Water Channel

• South Threshold to North Threshold
• North Threshold to Haven
• Haven to Cross
• Cross to No. 1 Buoy
• 1 Buoy to No. 8 Buoy
• No 8. Buoy To Platters
• Platters to Beach End

Harwich Harbour

• Harwich Harbour

Haven Ports

• Harwich International Port

River Stour 

• Mistley Quay and Approaches