This study investigated relationships between durations of inundation in River Red Gum wetlands and waterbird breeding, in particular the durations of flooding under nest trees that waterbirds need to breed successfully; and developed guidelines for managing water regimes in River Red Gum wetlands for waterbird breeding. The main study area was the middle section of the Murrumbidgee River in New South Wales. Average lag times between flooding under nest trees and first nests of Darter, cormorants, herons, egrets, Australian White Ibis and spoonbills ranged from two to four months following spring floods, and from four to seven months following autumn floods. The average lag times from flooding under the nest trees to first broods of ducks were one to two months, regardless of season of flooding. Average lag times to peak breeding of Darter, cormorants, herons, egrets, Australian White Ibis and spoonbills were three to five months following a winter/spring flood and six to nine months following an autumn f...