Flow regulation has significantly altered the natural seasonality of many rivers. These changes interrupt ecological cues that many aquatic species rely on for reproduction, dispersal, and recruitment. The Goulburn River in Victoria, Australia, delivers environmental water through seasonal flow pulses (‘freshes’) to restore elements of the natural flow regime. While these managed releases can reintroduce natural cues for some species, they may trade-off unintended consequences for others. For example, freshes overlap with the critical breeding window of platypuses (Ornithorhynchus anatinus), making this burrowing mammal especially vulnerable to high flows that might inundate nesting burrows and compromise juvenile survival. It is hypothesised, but untested, that burrow inundation could be avoided by releasing a pulse of environmental water prior to nesting (‘winter fresh’), to cue platypuses to build their nests higher on the riverbank where they are safe from high flows in spring. This research explores how environmental flows, particularly winter and spring freshes, impact platypus nesting behaviour and reproductive success. Specifically, we test whether: (1) platypus position the height of their nesting burrows in response to flow cues; and (2) reproductive success is greater in higher-elevation burrows with lower inundation risk. Overall, this project will evaluate how environmental flows can be used to support platypus recruitment while maintaining broader river management objectives. More broadly, it highlights the need to anticipate species-specific responses and unintended outcomes when setting ecological targets under increasingly variable climatic and hydrological conditions.