Pollution Impact Potential Maps — Surface Water Phosphate

Pollution Impact Potential (PIP) maps were generated separately for nitrate and phosphate to rank critical source areas (CSAS) relative to one from diffuse agriculture for both the Groundwater and surface water receptor. The PIP maps are generated by the EPA Catchment Characterisation Tool (CCT). The CCT delineates the CSAS displayed in the PIP maps by overlaying the hydro(geo)logically susceptible areas (the likelihood of nutrient transfer due to soil and geological properties along the near surface and/or subsurface Pathway) with nitrate or phosphate loadings. The nitrate and phosphate PIP maps for the surface water receptor combine the contribution from both the subsurface Pathway and the near surface Pathway while the Groundwater receptor maps only consider the contribution from the Groundwater Pathway. Surface Water receptor Phosphate PIP maps show the relative the pollution impact potential to surface water along the subsurface and near surface pathways due to phosphate loading. This map should be used to evaluate nutrient impact at the waterbody, subcatchment and catchment scale (at a resolution of less than 1:20,000). Pollution impact potential (PIP) maps rank the CSAS in Descending order of risk (where Rank 1 is the highest risk) and are available for the surface water receptor for nitrate and phosphate, and the Groundwater receptor for nitrate. Local pressure data has been used to generate the maps in agricultural areas where available. For urban, Forestry and the remaining agricultural areas, regional sources of pressure data have been used; these areas are marked ‘using regional loadings’ on the PIP maps.