1. Natalie Phillips (Environment Agency)
Approach for assessing WFD significant damage to GWDTEs in England & Wales
Natalie Phillips (Environment Agency)
Good morning, my name is natalie Phillips.
I am a hydrogeologist in the EA’s research team.

2. Acknowledgements Iain Diack, Anna Wetherell (Natural England)
Peter Jones (Countryside Council for Wales)
Andrew Brooks, Mike Carey, Susie Roy (Amec)
Mark Whiteman (Environment Agency)

3. Outline Classification overview
Identification of groundwater dependent sites
Characterisation
New qualitative assessment
Classification
Conclusions – lessons learned & future developments
Overview – picking up the milestones

4. Classification overview
Identification GWDTEs
Initial risk assessment
(national GIS data)
Local risk adjustment (workshops & GIS)
Significant Damage Assessment
(Detailed site analysis)
Characterisation
Classification
Stage 1
Stage 2
Three stages to the classification approach:
Stage 1 – identification of groundwater dependent sites by lead conservation organisations
Stage 2 – Characterisation of the sites in terms of chemical and quantitative risk. This is essentially a desk based study of data, and is intended as a screening process to reduce the number of site requiring conceptual modelling and expert assessment of significant damage for classification in Stage 3.
Stage 3 – Classification of sites. This process involves detailed consideration of the sites.
This approach has the advantage of using readily available data and knowledge to target resources on those sites that are most likely to be at risk of chemical or quantitative pressure.
Stage 3

5. Identification of GWDTEs
Stage 1
Data provided by National conservation bodies
Natural England & Countryside Council for Wales
Groundwater dependency assessed using:
National Vegetation Classification (UKTAG 5a-b, 2004)
Expert judgement
1,386 sites in RBC1
421 Natura2000 sites
Identification of sites…. the occurrence of vegetation assigned with a groundwater dependency rating by UK-TAG Wetland Task Team (paper 5a-b, 2004), using the UK National Vegetation Classification (NVC). Were this data was not available local expert knowledge was used.
The number of sites included in the interim classification assessment has increased. We are currently looking at the feasibility of developing a methodology for non-statutory designated sites i.e. Sites of local importance.

6. Risk Screening and Characterisation
Stage 2
Quantitative pressure
Abstraction pressure
Other gw level pressures
Pathway
Source
Receptor
Degree of dependence of ecology on groundwater
We use a Source-pathway-receptor approach for assessing risk.
Quantitative sources of pressure – assessed using abstraction data. Taking into account the size and location of abstractions.
Chemical sources of pressure –assessed using water quality monitoring data, or modeled data where this is not available.
Hydraulic connection – is assessed based on the nature of superficial deposits located between the site and the underlying groundwater body. Taking account of the thickness and permeability of those deposits.
Groundwater dependence of the site is assessed using National Vegetation Classification data.
The data are used to assign a score to each element of the assessment (pressure, pathway, and dependency). If any one of these elements is not present then there can be no risk to the receptor.
Chemical pressure
NO3/PO4
Other chemical pressures
Hydraulic connection
Drift thickness
Drift permeability

7. Assessing quantitative risk
High Risk = significant abstraction pressure, gw dependence + good hydraulic connectivity with the gwbody affected
Medium/low risk = Wetland located away from abstraction pressure and/or have low gw dependence + poor hydraulic connectivity to the groundwater body
No risk = No abstraction pressure and/or no hydraulic connectivity
The picture shows the location the wetland site in orange, with abstraction recharge circles shown in yellow. These show the abstraction volume as a proportion of the aquifer recharge. The larger the size of the circle, the larger the relative size of the abstraction
In a high risk site there would be....
(this is Bryn Marsh & Ince Moss) located on the Lower Coal Measures overlying the Sherwood Sandstone. The national method takes into account abstraction pressure at the waterbody scale and the site scale. However, local knowledge is required to ‘ground truth’ the assessment. In this case local knowledge was used to reduce the abstraction pressure since they are located in the sherwood sandstone which is poorly connected to the lower coal measures on which the site is located.

8. Assessing Chemical risk
RBC1 – phosphates
RBC2 – nitrate thresholds
Nitrate loading (NEAP-N) used if insufficient data
High risk = Local monitoring point with good connection to wetland + nitrate threshold exceeded
Medium/low risk = threshold exceeded in groundwater body/more distant monitoring
No risk = No chemical pressure and/or no hydraulic connectivity WQ TV
In the first cycle of RBP, PO4 monitoring and modelling data was used for the national assessment of chemical risk. However, this was considered to over estimate the problem.
- the application of surface water thresholds to groundwater
- uncertainties with respect to attenuation of phosphate levels between the site and the groundwater body
- Lack of confidence in the modelled data
Nutrient trigger values for groundwater were developed and tested by UKTAG. Nitrate groundwater body threshold values are now being used for the national risk screening.
Local information about other chemical pressures is used to modify the pressure scores if required. t

9. Proposed nitrate threshold values (mg/l N)
GWDTE category
Low altitude (<175mAOD)
Medium altitude (>175mAOD)
Any altitude
Quaking bog 4 1
Wet Dune_ 3
Fen (mesotrophic) and fen Meadow) 5 2
Fen (oligotrophic and wetlands at Tufa forming springs)
4.5
Wet Grassland  6  2
Wet Heath
Peatbog and woodland on peatbog
Wetlands directly irrigated by spring or seepage
Swamp (mesotrophic) and reedbed
Swamp (oligotrophic)
Wet Woodland  5
This table shows the threshold values developed by UKTAG.
The trigger values vary according to wetland type and in some cases the altitude of the site.
These values are more robust since they were developed using groundwater monitoring data and are linked to ecological condition

10. (7 step) Classification approach
Stage 3
For chemical status only, determine if a chemical threshold is exceeded in the groundwater body.
Define environmental supporting conditions (e.g. flow, level or chemistry) required to maintain dependent (plant) communities in a favourable state.
If the required environmental supporting conditions are in place, the groundwater body is considered to be at good status for this test.
If the required environmental supporting conditions are not in place, determine the magnitude of the departure from required conditions within the GWDTE.
Determine the proportion, if any, of the departure due to anthropogenic pressures compared to other pressures.
If this proportion is significant and a dependent community is damaged, the groundwater body is at poor status for this test.
If this proportion is significant, and a dependent community is not damaged, the groundwater body is at good status for this test, but is at risk of failing good status requirements in the future.
The UKTAG Guidance on Groundwater Quantitative Classification for the purposes of the Water Framework Directive (final draft April 2007) has identified a 7 step approach to the classification test relating to GWDTEs.
Don’t worry if you cant see the detail here. The handouts provide tables detailing the approach for chemical and quantitative pressure.
Essentially the method uses information about the level of risk (from the risk screening assessment) together with ecological condition data and site specific hydrogeological to establish whether a site has been damaged.
The magnitude of damage is determined by the degree of departure of the hydrological or hydrochemical regime from environmental supporting conditions.
This process requires considerable hydrogeological and ecological expertise in order to build up a conceptual understanding of the site and assess the cause and degree of impact.

11. Status Confidence Criteria Good High Low Poor No/low risk
Medium risk and condition favourable
Medium risk and condition unfavourable for reasons unrelated to groundwater
Low
Medium risk and unfavourable condition thought to be due to groundwater but no evidence of link
High risk and condition favourable
High risk and unfavourable condition for reasons unrelated to groundwater
High risk and unfavourable condition perceived to be due to groundwater but not corroborated by investigations
Poor
High risk and unfavourable condition, weak evidence of link to groundwater e.g. marginal failure of environmental conditions
High risk and unfavourable condition, strong evidence of link to groundwater e.g. Significant failure of environmental conditions
Status
Confidence
Criteria
For a site to be at Good status high confidence....
Conversely, for a site to be at poor status, high confidence there must be a
If the site is high risk Then the site is poor status, low confidence. Otherwise it is good status, low confidence.

12. Lessons Learned
Risk screening approach is a useful way to prioritise and target resources
Local ground-truthing of risk screening is essential
Classification requires experienced hyrogeologist and ecologist input as well as local conceptual understanding
Site specific monitoring and survey data is critical
Face to face workshops help with building conceptual understanding & reaching a consensus

13. Future developments Thank you for your time!
Expanded the list of plant communities for which there are groundwater dependency scores.
Thresholds for other chemicals (e.g. PO4)
Comparison of thresholds with databases held by other EU Member States on specific habitats
Expert knowledge/peer review of methods by WG-C members and contacts in other EU Member States
Better understanding of the fate of nitrate (and other chemicals) between groundwater body and the site
Significance of atmospheric N deposition
Development of approach for non-statutory sites
Measures - cost-effectiveness, response times, benefits.
Thank you for your time!