Little has been documented on large (>250 g), water-associated birds in the north-eastern KwaZulu-Natal, South Africa, that nest colonially and rely on suitable sites for breeding. The purpose of this study was to highlight these species and the importance of nesting sites for their effective conservation management. From 1920–2010, there were 622 records of 27 of these species breeding at more than 48 sites. Five sites accounted for 65% of these breeding events, four at Lake St Lucia, highlighting its importance for bird conservation. Several sites were abandoned. However, two new sites have established more recently (Nsumo Pan, Mkhuze Game Reserve; Nyamithi Pan, Ndumo Game Reserve) that are important in terms of number of individuals as well as variety of species. Some species (Pink-backed Pelican Pelecanus rufescens, Grey-headed Gull Larus cirrocephalus, Caspian Tern Sterna caspia, Great-white Pelican P. onocrotalus and African Spoonbill Platalea alba) have bred regularly but have used only a few sites, mainly at Lake St Lucia. Two species (Glossy Ibis Plegadis falcinellus and Black Heron Egretta ardesiaca) have bred once only on Lane Island (1961) and in trees at the mouth of the Hluhluwe River (before 1964) respectively. Two colonial sites hosted 10-12 species while others (n = 8) only two. Twenty-one sites were used by only one species. Two species (Pink-backed Pelican and Yellow-billed Stork Mycteria ibis) nest nowhere else in South Africa on a regular basis. Recommendations for the ongoing monitoring and conservation of these colonially-nesting birds in the region, particularly in terms of securing these sites, are made.