This work addresses a critical challenge in the restoration of seagrasses along the Adelaide metropolitan coastline's nearshore areas. While improved nutrient management has created conditions favorable for seagrass growth in previously depleted zones, bed sediment movement and mobility remain a barrier to natural seagrass recovery. Consequently, determining the hydrodynamic tolerance thresholds of seagrasses is crucial to effectively guide restoration efforts. Hydrodynamic (1 year of wave height and period from pressure sensor measurements) and morphological data (24 years of annual beach and nearshore profiles), as well as 40 years of wave hindcast modelled data were obtained at Grange Beach (South Australia) where seagrass recruitment (mostly Posidonia angustifolia) is naturally occurring, from which near-bottom orbital velocities and Depth of Closure (DoC) were calculated. Results indicate that wave-driven orbital velocities varied between 9.5 cm/s during modal conditions and 87.05 cm/s during the 99.5% exceedance conditions. The blue line (zmin, or the upper limit of seagrass presence) corresponds with the outer DoCout position. At Grange, seagrasses withstand storm conditions that produce higher orbital velocities than those suggested by the literature in the Mediterranean Sea. However, for seedlings, this threshold is substantially lower than that observed during storm events. This difference suggests that successful recruitment would have required a window of one or more years of low wave energy- conditions that coincidentally occurred in the region during a decade of drought that began in the early 2000s.