Source control • Management of a pollution event • Improvement of drainage • Management of local erosion due to ship wash • Management of access

Any management system should aim to control unfavourable influences, so that events such as trampling, pollution and/or eutrophication can be prevented or at the very least minimised.

Techniques include:

Source control

Source control, that is, the control of pollutant inputs to a saltmarsh system at source, can only be achieved through local cooperation with adjacent land owners, particularly service providers (such as water treatment companies) and farmers. Identifying the source of any pollution is key to managing the problem, e.g. sewage discharge or the runoff of fertilisers/pesticides (including their de-flocculants).

Maintaining close relationships with local landowners should remedy most of these problems. If, however, the problem continues then the relevant regulatory authority may need to be informed.

Management of a pollution event

Works to restore a saltmarsh after an oil spill can be important, because cleaning vegetation and sediments is very difficult. The main generic options are:

• Mechanical recovery offshore from the marsh.
• Dispersal (using oil spill dispersants) offshore.
• Booming of saltmarsh shorelines and inlets.

Of these options, if saltmarshes do become oiled, the best approach is often to allow natural recovery. However, intervention may be needed if:

• Free oil is present which may be spread with tidal action.
• Oil on the marsh surface threatens birds or other wildlife.
• The recovery time of vegetation is predicted to take several years.

If intervention is required, the main clean-up techniques include:

• Physical containment and recovery - booming and skimming of oil on the water in creeks and pumping bulk oil from the marsh surface, depressions and channels.
• Low pressure water flushing – however, results are variable, and the method must be used before oil penetrates the sediment.
• Sorbents - the rapid deployment of sorbents can reduce penetration into sediments.
• In-situ burning of oiled vegetation - while burning can increase damage, in winter, much of the vegetation is dead and the ground is likely to be wet enough to protect underground systems from heat damage.
• Vegetation cutting – this may be justified if there is a threat to birds or other wildlife. This will have a lesser effect on subsequent yield if it is undertaken in autumn and winter.
• Combined vegetation/sediment removal – this is an extreme method only used for serious cases, usually followed by rehabilitation (seeding and/or transplanting).

Improvement of drainage

The management of drainage inputs to the site to control freshwater input, for example, can also only normally be undertaken with the co-operation of adjacent landowners. As for source control, the key to resolving this issue is the identification of the problem and then getting agreement to any remedial action that is necessary. This may involve the control of water inputs via a sluice or improving drainage to facilitate the flushing of water though the marsh. It may include altering existing or historic drainage patterns (potentially associated with land claim/reclamation) within the saltmarsh itself.

Again, defining the objectives of the improvement action will be central to determining the action that ought to be undertaken. In some instances, for example, changes to salinity can increase diversity. However, large scale inputs of freshwater will most often lead to the loss of saltmarsh vegetation.

Management of local erosion due to ship wash

This can be simply resolved, normally in conjunction with the body responsible for navigation, through an imposed (and enforced) restriction on the speed of vessels, to a speed that reduces the wash caused. It may also be necessary to consider changing the direction of approach of vessels, to alter wave direction, in the vicinity of an eroding saltmarsh.

Management of access

Continued public access to a particular saltmarsh area might sustain localised trampling and possible disturbances of nesting birds (in the summer) or wintering wildfowl. Even small numbers of pedestrians (particularly walking dogs) can disturb roosting and nesting birds (Boorman, 2003). The identification of areas sensitive to trampling or disturbance should be undertaken to assess whether access is having a damaging effect. Where necessary, the provision of public information on potential adverse effects and limited or re-routed access may be acceptable (Boorman, 2003). This can be achieved through the use of information boards that encourage appropriate use. The existence of Public Rights of Way around much of the UK ’s coast, however, can represent a constraint to limiting or diverting access.