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Environmental monitoring of Jersey’s marinas and harbours

Ports of Jersey and the Government of Jersey are undertaking environmental monitoring of Jersey’s marina and harbour areas to gather baseline data on the quality of the water and sediments. The parameters being tested for are heavy metals, organotins and hydrocarbons.

Monitoring of Jersey‘s harbour and coastal environment is important:

  • to enable the collection of baseline data to assess the current environmental status of these areas
  • to track environmental changes and identify trends in water/sediment quality
  • where necessary, develop and implement measures to improve the quality of the marine environment

To obtain this information Ports of Jersey and the Government of Jersey are undertaking a 4-year collaborative chemical monitoring programme of the water and sediments of eight marina and harbour areas, alongside eight control sites around Jersey.

Monitoring parameters

A pragmatic approach was taken to the parameters tested in relation to the likelihood of the parameter being detected in a typical Jersey marina/harbour (e.g. localised industry, landfill, road and catchment run-off and maritime activities that take place that may result in a contamination of the marine environment). The parameters identified as most relevant for this monitoring are:

  • Organotins (TBT/DBT)
  • Heavy metals
  • Total hydrocarbons


Monitoring began in August 2019 at the Elizabeth Marina, St Helier. Four sediment and water quality samples were collected around its perimeter. Sediment samples were collected across four locations in the marina using a grab sampler. The water quality samples were taken from a central point within Elizabeth Marina, with 4 samples being taken over a tidal curve (high, mid, low and mid tide, to show whether different states of tide impact water quality).

Date taken:
Sea state:

Compound (units) Reading Standard

Interpretation of results

The results obtained have been compared against UK and EU chemical standards. These chemical standards provide a range of levels where chemical concentrations range from what is considered ‘normal’ background levels (not cause any harm to the environment) to levels which if exceeded could have a detrimental effect on the environment.


The sediment values have been compared against Centre for Environment, Fisheries and Aquaculture Science (Cefas) Action Level standards developed in the UK for the licensing of dredging activities.

​Contaminant or compound
​Action Level 1 (mg/kg dry weight (ppm))
​Action Level 2 (mg/kg dry weight (ppm))
​Organotins (TBT, DBT, MBT)
​PCBs - sum of ICES 7
​PCBs - sum of 25 congeners


Sediment results

  • TBT (organotins) were reported below Cefas Action Level 1, no action required
  • Heavy metals were reported below Cefas Action Level 1, no action required
  • Total hydrocarbon were detected at Cefas Action Level 1, no action required


The water results collected for this monitoring programme are compared against the EU Water Framework Directive (WFD) chemical standards, where a water body is either good status or failing to achieve good status.

The Environmental status of St Aubin's Bay (Report, November 2015)

Water results

The water quality analysis for all parameters tested were reported to be below the analytical limit of detection and are therefore ‘Good’ status when compared to EU WFD, Environmental water quality standards.

Monitoring schedule

In 2020 Ports of Jersey and the Government of Jersey will continue this monitoring in the St Helier and La Collette Marinas, along with a control site located in St Aubin’s Bay.

Proposed monitoring timetable

​Number of sites
Number of water samples
Number of sediment​ samples
​Elizabeth Marina
​St Helier Marina
​La Collette Marina
​Old / English / French Harbour
(St Helier)
​St Aubin's Harbour
​Bonne Nuit Harbour
​Gorey Harbour
​Control sites
​St Ouen's Bay - Water Splash

​St Ouen's Bay - L'Etacq

​St Aubin's Bay - Bel Royal

​St Aubin's Bay - First Tower


​Greve de Lecq

​Anne Port

​Havre des Pas

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