A largescale dieback of mangrove and saltmarsh has been documented around St Kilda (SA) following hypersaline brine leakage from an adjacent salt mine. We studied the impacts of this leak on soil salinity and wetland vegetation health over 9-months using bimonthly vegetation and soil porewater salinity surveys. More than 80 % of porewater samples had salinities greater than seawater (with a maximum of 278 ppt), with deeper soils having higher salinity than surface soils; indicating hypersaline groundwater. We used linear mixed effects model to explore the influence of spatial (distance from the leak, elevation, soil type) and temporal (rainfall and tide height) variables on soil salinity and vegetation condition over time. We found little evidence for improvement in soil salinity or vegetation condition across the site over time, although there was some indication that tidal flushing may be helping soil remediation in some parts of the site, and that areas of higher elevation with coarser soils were less impacted. Despite the lack of improvement observed, this research has been critical for better understanding the processes and mechanisms of impact at this coastal wetland site, as well as informing expectations around both soil and vegetation recovery timelines.