Please note that this guidance is for information only; it should not to be used in the classification of ecological status until information is available on which of the species listed are considered ‘high impact'.
The alarm list contains species thought to pose a risk to surface waters and their ecological status under the EC Water Framework Directive, but whose presence has not yet been recorded in Great Britain.
The working paper outlining the impact classification of alien species has been updated (05/02/2014) following the completion of additional risk assessments by GBNNSS and Phase 3 of the review of Environmental Standards.
This method statement describes a system for assessing and classifying surface water bodies (rivers, lakes, transitional and coastal) based on the presence of high impact alien species.
The Final Recommendations on Environmental Standards following phase 3 of the review have been published (November 2013). This report includes zinc standards.
The aim of this paper is to provide guidance on (a) the pressures from alien species on river, lake, transitional and coastal water bodies; (b) data required for carrying out risk assessments for Article 5 analyses; and (c) pressure thresholds at which water bod