The Colligan Estuary is a significant tidal water body on the southern coast of Ireland in County Waterford. It forms a key part of Dungarvan Harbour, draining a catchment area of approximately 101 square kilometers. The estuary is designated as a transitional water body under the Water Framework Directive and is part of the Dungarvan Harbour Special Protection Area. Its ecological status is currently assessed as Poor due to significant pressures, primarily from urban wastewater sources. The area is a mix of natural foreshore and developed flood defenses, with the historic town of Dungarvan and the village of Abbeyside situated along its banks, offering scenic views and integrated access to the Waterford Greenway.