Combined Monitoring-based and

Article 16 also states that the list of priority substances needs to be reviewed by the Commission every four years. Eor the definition of the first list of priority substances, in accordance with the provisions of the WED, a Combined Monitoring-based and Modelling-based Priority Setting scheme (COMMPS) was devised. The implementation of this scheme also involved a data collection exercise to assess the level of contamination by chemical substances in Europe. This led to the development of the COMMPS monitoring database. But this was a one-off exercise (the database was never updated) and it was therefore recognised as fundamental that a data collection process should be carried out on a regular basis, with data to be included in the Water Information System for Europe (WISE) developed under the Common Implementation Strategy (CIS). 

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