Climate change presents several increasing challenges, in particular relating to water management and allocation. This has given rise to a search for mitigation strategies, including methods of carbon sequestration and storage. Phragmites australis is one species that can provide these ecosystem services. P. australis thrives in wetland conditions with periodical flooding, allowing for a drying period between flooding events. Within Australia's Murray- Darling Basin, the Great Cumbung Swamp has a highly valuable P. australis stand which is managed with environmental flows. This stand is used as a case study to determine the effects of different watering levels on the biomass, carbon proportion, and carbon content distribution in P. australis in above- and below-ground detail, and at an organ level. Satellite imagery and inundation histories were used to establish the three watering treatments of frequently, moderately, and infrequently watered. It was found that with an increase in inundation events the level of carbon and biomass present in P. australis also increased. The driest treatment was unable to produce much above-ground mass with the vast majority stored below-ground to survive water stress. As this study quantified the amounts of carbon found in each organ type within each treatment, estimations can now be made across the Great Cumbung Swamp. The results from this study also lead the way to further future findings including how many kilograms of carbon are additionally sequestered with each further megaliter of environmental water. Through the discovery of how watering influences carbon sequestration and storage, the management of wetlands can be undertaken in such a way to allow them to assist in climate change mitigation, or at a minimum, to prevent carbon loss back into the atmosphere. The findings of this study also have the potential to be applied globally and to other wetland species, with adjustments and considerations.