Summary of possible effects of maintenance operations in ports and harbours in marine SACs and suggestions for means of avoiding, minimising and addressing them

(Ben = Beneficial, Min = Minimal, Adv = Adverse)

Port and Harbour Operations

Potential issues, key processes & potential impacts


and comments



Potential impacts on marine SACs




Possible means of avoiding, minimising and addressing impacts

Issue: Maintenance wastes and runoff

Key process: Toxic contamination

Non-toxic contamination

Potential impact: Wastes from the cleaning of port and harbour infrastructure and boat/ship maintenance areas can contain harmful contaminants that may have toxic effects on marine wildlife. Cleaning agents include biocides, bleach, and detergents. The combined effects of these substances needs further study.

Bleach and other chlorine containing chemicals used to clean harbour structures may have toxic effects on shellfish and fish, and reduce the diversity of marine wildlife in localised areas.

The use of detergents for cleaning operations can form phosphate-rich waters that may encourage the formation of algal blooms which can cause oxygen depletion and may result in the localised suffocation of animals.

The effects depend on scale of maintenance operations, background water quality, maintenance techniques used, amounts/types of contaminant in wastes and proximity of marine features.

Impacts are likely to be localised and temporary due to dilution, however there may be more of a problem in enclosed areas or areas with low tidal flushing.



Cleaning agents tend to only be a problem when used in high concentrations and often present the only effective means of ensuring safety in harbour areas.



























Educate, encourage and train harbour staff.

Raise public awareness of environmental management in harbours.

Ensure staff follow good housekeeping practices.

Provide separate collection facilities for maintenance wastes.

Consider constructing bunds, sumps and/or installing oily separators to collect wash down wastes and reduce contaminants entering the harbour where necessary.

Use environmentally sensitive alternatives to biocides or harmful cleaning agents wherever practical.

Where no suitable effective alternative is available, minimise amounts used and frequency of use where practical.

Give high priority to finding effective alternatives so that the use of substances containing phosphates and chlorine can be stopped.

Issue: Anti-fouling paints

Key process: Toxic contamination

Potential impact: Most anti-fouling paints are toxic. When allowed to accumulate in high concentrations in sediments they can be toxic to non-target marine organisms. The adverse effects of TBT on marine life are well known, particularly with regard to shellfish and molluscs. Copper-based anti-fouling paints are less toxic to non-target species, but may still have toxic effects in high concentrations.

The use of TBT anti-fouling paints on commercial vessels is at present the most effective option available. However, the IMO have recently decided to ban the use of TBT in antifouling paints. Research and development is ongoing to find and test alternative coatings. Copper anti-fouling paints have been relatively widely used on vessels and are the BPEO available to the marine industry at present. Toxic effects from copper to non-target species are only likely as a result of high amounts in sediments due to continued spills or careless maintenance operations. Non-toxic alternatives are also available, but are less effective.


Develop guidance to encourage the careful use, handling, storage and disposal of antifouling paints in the harbour.

Provide separate reception facilities for vessel maintenance wastes.

Provide ‘scrub-off’ facilities to collect maintenance residues from boat cleaning operations.

Consider the use of alternative anti-fouling agents, bearing in mind their effectiveness and operational efficiency.


Useful operational and environmental guidance for recreational harbour operations

  • Good Practice to Boating and the Environment (British Marine Industries Federation 1997).
  • Navigate with Nature - Are you on Course? (UK CEED 1998).
  • Pollution Prevention Guidance Note 14: Marinas and craft (PPG 14) (Environment Agency, 1996).
  • PPG9 – Planning Policy Guidance on Nature Conservation. (DoE 1994).
  • The Code of Practice for the Construction and Operation of Marinas and Yacht Harbours (The Yacht Harbour Association 1992).
  • Tide Lines- Environmental Guidance for Boat Users (Royal Yachting Association 1997).
  • Managing Personal Watercraft: A guide for local and harbour authorities (BMIF et al 1999).
  • UK Marine SACs Project, Task 2.1 Recreational User Interactions: Framework for reviewing and managing potential recreational impacts (UK CEED 1998 and 1999 in preparation)

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