Yes, an unmaintained retention pond can flood. If the local government does not own it, it is the responsibility of the homeowners’ association or the individual owner to keep the pond in maintained and working order. This includes performing regular inspections, particularly after severe storms or heavy rain, to identify and repair areas of erosion, gullies and other damage; removing sediment and debris from the pond before it reaches the outlets; and beautifying the surrounding banks with grass, shrubs and other vegetation.