1. Case study for the discussion on the use of article 4. 4
Case study for the discussion on the use of article 4.4.c WFD: Nitrate in Groundwater (NL)
Jacqueline Claessens

2. General description
The current policy aims to improve groundwater quality (nitrate)
Standard for nitrate is exceeded in some GWBs
Due to over fertilization in the past > historical load in subsurface
Slow response time of subsurface > difficult to predict how and when historical load will manifest
Decrease of concentrations due to
hydrological system > dilution
degradation capacity of subsurface (OM and iron sulphides)
Side effect is increasing hardness and release of metals
Toekomst grondwatermonitoring | 18 mei 2016

3. Pressures
Input at the surface decreased since ‘90 due to national policy
Decrease was not sufficient to reach good status in all GWB in 2015
Highly conductive sandy aquifers > continuous supply of nitrate from historical load
Fraters et al., 2016
Toekomst grondwatermonitoring | 18 mei 2016

4. Measures Since 2006 fertilizer policy based on application standards
Aim is to restrict the loss of nitrate to the soil
Decline of 408 millions kg/yr ( ) to 185 millions kg/yr ( )
With intended policy the number of drinking water protection areas with elevated nitrate concentrations will decrease from 25 % ( ) to 7% ( )
Toekomst grondwatermonitoring | 18 mei 2016

5. Justification of the use of article 4.4.c
The length of time needed to overcome the historical load is determined by:
Input at the surface
Hydrological system
Degradation capacity of the subsurface
Settlement of historical load due to hydrological system may therefor be covered by art 4.4.c
Precondition: Input concentrations sufficient to reach good status
Toekomst grondwatermonitoring | 18 mei 2016

6. Discussion
Is it possible to use article 4.4.c when input concentrations are sufficient to reach good status in time?
Is the settlement of the historical load based on conceptual model covered by natural conditions as is used in article 4.4.c?
Is it possible to use article 4.4.c when additional measures are required in specific (e.g. drinking water protection) areas?
Are additional measures obliged to shorten the period after 2027 to reach good status?
What conditions?
May cost-benefit analyses be considered?
Toekomst grondwatermonitoring | 18 mei 2016