ICOLLs (Intermittently Closed and Open Lakes and Lagoons and some lakes that now have permanent entrances) are particularly vulnerable to climate induced sea level rise. Further, the low lying foreshores of many in NSW (Tuggerah Lakes, Terrigal Lagoon, Wallis Lake, Lake Macquarie) are densely populated. As a result, a large number of existing developments are already flood affected and many more have floor levels only slightly above flood levels. At most ICOLLs, a rise in sea level will translate into a similar rise in flood level. As a result there will be a significant increase in the number of buildings inundated and hence a substantial increase in flood damages.

This paper explores the feasibility of management measures to protect existing developments (levees, house raising, “Thames” style barriers). However, in some places redevelopment at a higher level or even the complete removal of existing developments may be the only viable solution. The latter will obviously cause significant social hardship but must be considered.

If the predicted sea level rates of rise occur (0.4m by 2050), NSW Councils will have little time to plan suitable actions and enact long term strategies to ensure the safety of existing developments. Further, to be confident that future developments are adequately protected, Councils will need to ensure that all new developments are subject to flood related development controls in line with the recently released NSW Government Sea Level Rise Policy.