WFD - Annex V - 2.4.3. Operational monitoring

Operational monitoring shall be undertaken in the periods between surveillance monitoring programmes in order to:

• establish the chemical status of all groundwater bodies or groups of bodies determined as being at risk,
• establish the presence of any long term anthropogenically induced upward trend in the concentration of any pollutant. 

Operational monitoring shall be carried out for all those groundwater bodies or groups of bodies which on the basis of both the impact assessment carried out in accordance with Annex II and surveillance monitoring are identified as being at risk of failing to meet objectives under Article 4.
The selection of monitoring sites shall also reflect an assessment of how representative monitoring data from that site is of the quality of the relevant groundwater body or bodies.

Operational monitoring shall be carried out for the periods between surveillance monitoring programmes at a frequency sufficient to detect the impacts of relevant pressures but at a minimum of once per annum.

(see Annex V 2.4.3. Operational monitoring - L327/62)