1. SURFACE WATER /GROUNDWATER INTERACTIONS
GROUP 4
SURFACE WATER /GROUNDWATER INTERACTIONS
Tony Marsland

2. KEY ISSUES Integration of surface water and groundwater objectives;
Relationships between status and quality, “Main Pollutants”, “Priority Substances”;
Determination and application of standards;
Definition of / benchmarks for Good Chemical Status;
Quantitative triggers in respect of quality;
Potential new High chemical status class;
Use of ‘prevent or limit’ measures.

3. RELATIONSHIP OF SURFACE WATER & GROUNDWATER OBJECTIVES
Surface water objectives are contained within groundwater objectives;
Some substances for which you might want groundwater objectives/standards would not have equivalent EQS in surface water;
Surface water standards not universally applicable to groundwater;
Some evidence that there can be significant losses in the hyporheic zone, so it may be unreasonable to have direct read across from surface water in some circumstances.

4. INTEGRATION OF OBJECTIVES
“Where more than one objective …. relates to a given body of water, the most stringent shall apply”;
What will this mean in practice??
Objectives may be different (may not be obvious which are the most stringent);
have suggested “achieve the best environmental outcome whilst maintaining sustainable use of water, consistent with the overall purposes of the WFD.”

5. WHAT IS A POLLUTANT?
….any substance liable to cause pollution, in particular the Main Pollutants listed in Annex VIII;
Pollution is “the direct or indirect introduction, as a result of human activity, of substances or heat into air, water or land which may be harmful…….”
You cannot have natural pollution;
Good Chemical Status does not necessarily mean good quality;
Priority Lists were drawn up for surface waters and have an indirect relationship to groundwater – do we need a priority list for groundwater?

6. RELATIONSHIP BETWEEN GROUNDWATER CHEMICAL STATUS AND QUALITY
Naturally elevated concentrations giving rise to poor quality but good status groundwater
POOR STATUS
Polluted groundwater
Receptor-based standard
Contaminated (altered) groundwater
ANTHROPOGENICALLY INFLUENCED
Variability in natural baseline quality due to hydrogeochemistry
Increasing pollutant concentration
Increasing concentration
GOOD STATUS
NATURAL QUALITY
Level of detection/
quantification
Pristine or high quality groundwater
Notes : Waters with concentrations of substances to right and above thick dashed line are subject to anthropogenic influences. Good status groundwaters include those with anthropogenic influences (but not polluted) and those with naturally elevated concentrations above what would normally be considered appropriate for most groundwater uses.

7. HIGH STATUS
Need to look carefully at purpose and costs & benefits of High Status;
Is there an overwhelming reason to create High status, particularly if you have appropriate prevent or limit measures;
trend reversal and restoration would not apply;
overall status would still be good;
Other options to high status such as new drafting in a Directive to allow a Protected area for high quality;
Must be careful about not preventing all development by creation of high status.

8. SUBSTANCE ISSUES
Need to look at different groups of substances as they have differing relationships with natural background quality;
As far as potential impacts are concerned, how do we prioritise our efforts - which substances are of most concern;
What is the relationship between the lists in the Groundwater Directive and the definition of pollutant in the WFD??

9. GROUPS OF SUBSTANCES
Group A – synthetic substances not found in the natural environment eg organic solvents and most pesticides;
Group B – naturally occurring substances which are not normally found in elevated concentrations in groundwater eg arsenic, bromate, mercury, cadmium;
Group C – naturally occurring substances with variable natural background concentrations.
NB no judgement about the potential to cause harm in these groupings.

10. STANDARDS FOR WHAT?
Status Definition – prevention of deterioration of and restoration to. To make good chemical status “operational”;
Remediation standards – targets for restoration of groundwater quality at sites polluted by point sources and contaminated land;
Prevent or Limit standards (Control standards) – release of pollutants to all groundwater from discharges, current activities etc.

11. STATUS DEFINITION STANDARDS
Need to integrate surface water and groundwater objectives;
Flux rather than concentrations that is important;
Different relationships between and within water bodies;
Difficult to envisage how a single set of Europe-wide standards (eg Drinking Water directive) could be applied to meet all objectives, particularly for Group B and C substances;
Recommend framework for setting standards, but set these locally (groundwater body) to meet local objectives.

12. Varying relationships of groundwater bodies within river basins
EXAMPLE 1 : Major contribution to river flow – status of watercourse heavily dependent on groundwater contribution - potentially close relationship between surface water status and groundwater standards, but losses in the hyporheic zone may vary between substances. Baseline quality may vary widely between A and B due to mineralogy and residence time.
Standards for groundwater remote from natural discharge points may be set as concentrations reflecting groundwater use (eg abstraction)
Standards set at point of discharge into receptor may be expressed as total loading (concentration x flow) A
EXAMPLE 2 : Little influence on surface water status – more flexibility to set standards to reflect other groundwater uses.
Borehole B
River
Groundwater flow
Principle of no deterioration in groundwater chemical status applies in all cases.

13. PREVENT OR LIMIT STANDARDS
Control releases from the surface to all groundwater – ie existing Groundwater Directive;
Use with authorisations, codes of practice, general binding rules etc.;
What do you prevent ? - a priority list of substances ? - with a compliance point at water table;
What do you limit ? – all other pollutants, compliance point at some point down-gradient in the saturated zone;
Need to explore a mechanism for producing a prevent list of priority substances that are relevant to groundwater;
If necessary, it is technically feasible to have Europe-wide standards for Group A substances, but for everything else, natural background must be factored in.

14. COMPLIANCE POINTS X A B ~ ~ X ~ X ~ ~ ~ ~ ~ ~ ~ ~ ~ Receptor
(eg abstraction borehole)
Source
Soil Zone
Unsaturated Zone
Leaching or discharge of pollutants X
Water table A B ~ ~ X ~ X ~ ~
Compliance point for ‘prevent’ substances
Saturated Zone ~ ~ ~ ~ ~
Compliance points for ‘limit’ substances ~ ~
GROUNDWATER FLOW

15. GROUNDWATER DIRECTIVE
Schematic of relationships between substances listed under the Groundwater Directive and ‘pollutants’ defined under the Water Framework Directive
SUBSTANCES that are non-polluting due to their concentrations or effects (contaminants)
Substances that are Main Pollutants but are not listed in existing GWD eg Nitrate.
Non-polluting
Concentration
MAIN POLLUTANTS
(WFD Annex VIII)
POLLUTANT
PRIORITY SUBSTANCES
(Annex X)
Other pollutants (not in Annex VIII)
LIST I
LIST II
Not Listed
List I substances that are not Main Pollutants eg non-persistent hydrocarbons.
GROUNDWATER DIRECTIVE
(Listed substances shaded)

16. REMEDIATION STANDARDS
Site scale, pollution already there;
Need to have regard to meeting status requirements of groundwater body – but compliance point can be at defined receptors;
Need to differentiate between recent and historic pollution;
Achievability of remediation;
Cost-benefit;
Other receptors;
Not appropriate to use Daughter Directive to set standards – should be done locally.

17. Spatial relationships of compliance points for different types of standards
‘Limit’ compliance point (eg abstraction, or other 'use' of groundwater)
‘Prevent’ compliance point
Point source discharges x o x x x o x
GROUNDWATER FLOW
GROUNDWATER BODY x x x
Compliance point at which loading necessary to protect watercourse is assessed and possibly converted to a concentration in groundwater
Historically contaminated land/polluted groundwater (local restoration standard/target, potentially linked to down-gradient status definition compliance point)
Status Definition compliance points

18. Figure 3a : Procedure for taking account of surface water/groundwater interactions in setting Chemical Status definition standards.
Delineate groundwater body and identify all receptors and uses
INITIAL CHARACTERISATION
Identify interactions with surface waters, ecosystems etc
INITIAL CONCEPTUAL MODEL
Assess chemical quality requirements of these receptors
Does groundwater interaction clearly have significant effects on Article 4 objectives for surface waters and protected areas ?
YES
Groundwater status likely to be poor based on impacts on other receptors NO
Determine chemical status based on
A) presence of saline or other intrusions;
B) Comparison with any standards derived under Article 17 (eg based on groundwater use, indicators of good chemical status etc)
Set target values and compliance points within the groundwater body
Conduct further characterisation, refine conceptual model and consider standards in more detail (Figure 3b) NO
By comparison with the above, is groundwater status good and groundwater body not at risk?
Groundwater body is “at risk” or of poor chemical status
YES
No further action, other than targeted surveillance monitoring

19. Figure 3b : Procedure for taking account of surface water/groundwater interactions in setting Chemical Status definition standards.
Determine detailed rates of exchange between surface waters etc. and groundwater body
FURTHER CHARACTERISATION NO
Using refined conceptual model, is groundwater having a significant impact on surface receptors?
REFINED CONCEPTUAL MODEL
YES
Define EQS values and/or acceptable loadings at defined (Status definition) points along watercourses, in wetlands etc.
Review results of groundwater chemical status definition arising from Initial Characterisation in the light of any new data arising from Further Characterisation
Convert concentration/loading requirements needed to protect surface water/ecosystems into a maximum acceptable concentration in groundwater immediately up-gradient in the groundwater body by considering relative contribution of groundwater flow
Combine standards derived for surface waters (including wetlands etc) and groundwater and identify “most stringent” standards (in most cases these are likely to be related to surface water), then consider whether standards within the groundwater body can be adjusted, based on conceptual model and variations in natural groundwater quality
Continue to use groundwater-based standards only
Review operational monitoring data and assess compliance with standards on a periodic basis

21. SOME CONCLUSIONS
Overall it is not considered that a technical case for high status has been demonstrated;
We need to differentiate between groups of substances for the purposes of defining standards – a single methodology will not work (Note background quality);
Potential prioritised list of substances for groundwater to give some meaning to “prevent or limit”;
There are differences between the existing Groundwater Directive and WFD in terms of pollutant lists - can these coexist until 2013?;
There are three different circumstances where standards might be applied - and different compliance points, which must be defined together with the standards.

23. MONITORING DATA Distinct roles :
to assess the quality of a groundwater body to determine compliance with objectives (eg good chemical status) and taking into account background quality;
to assess the impact of specific activities and potentially to assess compliance with a standard, also taking into account background quality (comparable with "requisite surveillance" under the existing Groundwater Directive);
to derive measures and monitor progress.
Need to make sure that you distinguish between monitoring requirements and priority list definition - they are separate processes;

24. POTENTIAL APPLICATION OF PREVENT OR LIMIT STANDARDS?
LIMIT
Non-polluting
vertical axis represents concentration of substance
Increasing Concentration
PRIORITY SUBSTANCES
(Annex X) +
Proposed Priority Substances for groundwater ?
POLLUTANT
Other main pollutants (in Annex VIII)
Other pollutants (not in Annex VIII)
MAIN POLLUTANTS (Annex VIII)
Group A : Synthetic substances (of anthropogenic origin only).
Group B : Naturally occurring substances not normally found with elevated concentrations.
Group C: Naturally occurring substances with variable natural background concentrations that can also be introduced by man.