GWDTE Threshold Value development in UK UK Wetland Task team has developed TV’s for GWDTE categories using 3 sets of data: Groundwater quality monitoring of water feeding GWDTE’s Groundwater chemical measurements In GWDTE’s Literature

Develop TV’s our approach…

GWDTE TV Data sets 180 Wetlands with good hydrogeological connection to GW-body, contained 475 GWDTE’s GWDTE’s in 11 categories ANOVA revealed that ‘intensity of land-use was important (upland <-> lowland)

Rules The TVs must lie above the mean (per vegetation category) and preferably above the 75th percentile for sites in good condition The TVs must lie below the mean (per vegetation category) and preferable below the 25th percentile for sites in poor condition The TVs must include the knowledge from the within site research The TVs must reflect the available knowledge from the literature The TVs are, where possible, a round number (or ½) to reflect the uncertainty in the data The TVs must include expert knowledge from the Wetland Task Team members

Groundwater dependent Wetland TV’s (mg/l NO3)

Groundwater dependent wetland Threshold Values; use in characterisation and classification If GWDTE damaged (and likely caused by nutrient pressure) and Threshold Value exceeded in relevant groundwater monitoring point then At risk and further investigation Result of investigation is used in classification and could trigger remedial action Also used in prevent and limit / no deterioration