The aims of the methodology are to determine whether water bodies (rivers, lakes and transitional) identified in Northern Ireland are at risk or not at risk, with low or high confidence, from the combined pressures of abstraction and flow regulation. The deviation from natural flow or the flushing/level change for lakes according to ecological thresholds will be used to determine the risk, in line with UKTAG guidance1 . A two tier approach has been adopted. Tier 1 involved the screening of river, lake and transitional water bodies using a simple presence and absence assessment. A Tier 2 assessment refined the Tier 1 assessment by using a water balance approach where the magnitude of the pressure and sensitivity of the water body are considered. The assessment of abstraction pressures on groundwater is recorded elsewhere.