The magnitude of potential environmental impacts caused by boating facilities developments depends on factors such as the actual location of the development, the scale of the scheme, construction methods and project design and implementation.

Those marina developments that irreversibly modify existing natural habitats are likely to cause the most significant impacts. In particular, where land claim is part of the development, the potential to modify the habitat is greater.

Isolated swing moorings and limited pontoon provision are likely to have the least relative impact, although their cumulative impact may be more significant in the vicinity of those features which are already experiencing stress from other sources, such as agriculture, industry and also other recreational activities.

Dredging may induce turbidity which, depending on the scale, may affect tidal regimes. In addition, deep dredging may disturb large benthic communities on the sea bed, although evidence of long term impact is limited.

There is a trade off between maintaining adequate flushing characteristics of marina basins by dredging and causing increases in turbidity by the dredging operation.

The disposal of dredge spoil may have the beneficial result of removing contaminants from marine sediment, many of which are from industrial and agricultural sources, although the location of disposal is an important issue as is the resuspension of the contaminants in the water column.

Disposal may also cause potential problems associated with the smothering of sea bed communities.

Evidence suggests that water quality in a low flushing marina basin can undergo a number of changes. In particular, water temperature may increase, dissolved oxygen levels may decrease, and there may be increases in certain pollutants such as copper from antifouling paints.

Terrestrial and non-marine invertebrates, abundant in sand dunes and salt marshes, are unlikely to be effected by marina and other facilities development unless the construction involves significant modification of their habitats through land claim.

Aquatic estuarine communities, including algae, worms and molluscs, are greatly affected by the loss of estuarine area through land claim and locked basins. This also has a detrimental effect on fish and bird populations which feed on the organisms.

The impact of boating facilities’ operations is dependent to a large degree on the nature of the management procedures on site.

The provision of adequate facilities for the reception of various wastes, the adoption of run-off minimisation strategies and effective general site management can all improve the environmental performance of a facility.

Quantities of antifouling paint may enter the water in the vicinity of boat lift out areas, where craft are washed down, and in maintenance areas, where craft are scraped. These activities can remove a large amount of paint which invariably enters water from the landside. Where present in significant concentrations, the biocides have implications for marine organisms, although there is limited data available to confirm the nature and scale of such impacts.

An existing slipway may have a continuing impact on a feature, site designation suggests that the site can support the facility at its current level and type of use. However, if usage levels of the facility increase greater impacts may occur, such increase therefore require close monitoring.

Blank Squares - not applicable

m - minimal

w - observable, likely to be location specific

w * - observable at certain times, minimal at other times

l - appreciable, although depends upon scale of operation

• anchor drag and maintenance activities carried out at low tide

• this refers specifically to the impact of maintenance activities such as hull scraping on mud banks at low tide

• impact of operations at facility, not including impacts of construction

• concentrations of biocide in the vicinity of facility, not including general impacts of antifouling paints

• concentrations of sewage and other discharge in the vicinity of facility, not including general impacts

• disturbance to wildlife during operation of facility, not including impacts of construction

• impacts due to operation of facility, not including general impacts of recreational activities

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