Environmental water is increasingly used to support functioning river and floodplain ecosystems, including reedbeds, where maintaining wetland vegetation condition is a common objective. These restorative actions require knowledge of the needs of the river and its biota, and ongoing monitoring is fundamental to the adaptive management of environmental water, providing a way to track progress against objectives or targets. Drone-based remote sensing allows for the consistent collection of high-quality data in locations such as wetlands where access is limited. Using data obtained using unoccupied aerial vehicles (UAVs) and convolutional neural networks (CNNs), we estimated the cover of Phragmites australis (common reed) in the reedbed of the Great Cumbung Swamp in semi-arid western New South Wales, between October 2019 and March 2021. Using these data we examine the role of reedbed condition and prior environmental watering in the response of reedbeds to flooding. The first year of surveying (2019) was a very dry period, when environmental water was used to maintain the condition of the central reedbed. In 2020, large-scale flooding occurred where all (9) plots within the reedbed were flooded. Prior to the flooding event, sites that had received environmental water had a significantly greater cover of Phragmites australis. The sites that were not managed with environmental water had very low cover (<1%) of reeds prior to the flood event and transitioned from a critical condition to a Poor or medium condition following flooding. Using these data, we demonstrate the role environmental water plays in filling the gaps between large flood events and maintaining the condition and resilience of reedbeds.