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Helsinki Convention: trans-boundary watercourses and international lakes

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Helsinki Convention: trans-boundary watercourses and international lakes

The Helsinki Convention aims to prevent and control pollution of trans-boundary watercourses and international lakes by developing international cooperation.


Council Decision 95/308/EC of 24 July 1995 on the conclusion, on behalf of the Community, of the Convention on the protection and use of trans-boundary watercourses and international lakes (Helsinki Convention).


The Convention was signed on behalf of the European Community in Helsinki on 18 March 1992. It establishes a framework for cooperation between the member countries of the United Nations Economic Commission for Europe (UNECE) on the prevention and control of pollution of trans-boundary watercourses by ensuring rational use of water resources with a view to sustainable development.

The Convention gives a series of definitions:

  • "trans-boundary waters" means any surface or ground waters which mark, cross or are located on the boundaries between two or more States (where trans-boundary waters flow directly into the sea, they end at a straight line across their respective mouths between points on the low-water line of their banks);
  • "trans-boundary impact" means any significant adverse effect on the environment resulting from a change in the conditions of trans-boundary waters caused by a human activity, the physical origin of which is situated wholly or in part within an area under the jurisdiction of another Party to the Convention (such effects include effects on human health and safety, flora, fauna, air, climate, etc.);
  • "Riparian Parties" means the States that are signatories to the Convention that border the same trans-boundary waters;
  • "Hazardous substances" means substances which are toxic, carcinogenic, mutagenic, teratogenic or bio-accumulative, especially when they are persistent.

The Parties to the Convention undertake to take all appropriate measures to prevent, control and reduce any trans-boundary impact.

This means they must:

  • ensure that trans-boundary waters are managed in a rational, environment-friendly manner;
  • ensure that trans-boundary waters are used in a reasonable and equitable way;
  • ensure conservation and restoration of ecosystems.

Any action designed to deal with water pollution must attack the pollution at source. Measures must not result directly or indirectly in a transfer of pollution to other parts of the environment.

Actions of the Parties to the Convention must be guided by the following principles:

  • the precautionary principle: action to avoid the release of hazardous substances must not be postponed, despite the lack of a proven causal link between the substances and the trans-boundary impact;
  • the polluter pays principle: the costs of pollution prevention, control and reduction measures must be borne by the polluter;
  • water resources must be managed so that the needs of the present generation are met without compromising the ability of future generations to meet their own needs.

The means of reducing trans-boundary impact are legal, administrative, economic, technical and financial measures. The Parties may adopt water quality criteria and introduce emission limits for discharges into surface waters. This type of pollution may be avoided or reduced by using low-pollution technology.

The States must establish programmes for monitoring the condition of trans-boundary waters.

The Convention encourages cooperation among the Riparian Parties by means of bilateral and multilateral agreements for the introduction of harmonised policies, programmes and strategies to protect trans-boundary waters. These may, for example:

  • collect information and compile inventories on sources of pollution which have (or may have) trans-boundary impact;
  • set up joint monitoring programmes;
  • adopt emission limits for waste water;
  • establish warning procedures;
  • carry out environmental impact assessments;
  • evaluate the effectiveness of programmes dealing with this type of pollution.

The Riparian Parties must provide mutual assistance upon request should a critical situation arise.

The Parties to the Convention must cooperate on research and development activities regarding effective techniques for preventing, controlling and reducing trans-boundary impact (methods of evaluating the toxicity of hazardous substances, knowledge of the effects on the environment of polluting products, development of environment-friendly technologies or manufacturing methods, etc.).



Entry into force - Date of expiry

Deadline for transposition in the Member States

Official Journal

Decision 95/308/EC



OJ L 186 of 5.8.1995

Last updated: 13.11.2007