New River estuary is a shallow intertidal dominated estuary in Southland, New Zealand. The estuary drains a 4314km2 catchment comprising of >75% pasture, of which 60% is intensive pasture. Historical land reclamation and intensification of land use in the catchment have led to significant degradation of the estuary over time. New River estuary is a part of Environment Southland’s long term estuary monitoring program, which includes broad scale habitat mapping in addition to sediment chemistry, sedimentation and macroinvertebrate community composition at 5 key sites across the estuary. Gross eutrophic zones (GEZ) represent areas with >50% macroalgal cover, >25% mud content and depleted sediment oxygenation (e.g. redox potential discontinuity depth <5mm). Since 2001, GEZ areas have increased from 23ha or 1% of the intertidal area to 428ha or 15% of the intertidal area in the estuary. Seagrass loss in the Waihopai Arm (the upper estuary) has been catastrophic, with >94% of seagrass displaced by fine sediment and macroalgal mats between 2001 and 2018. The widespread and rapid increase in nuisance macroalgal growth has contributed to sediment anoxia, trapping of fine sediment and accumulation of nutrients in these GEZ areas, and resulted in a severely degraded macroinvertebrate community in which only a few tolerant species persist. This state of severe degradation primary reflects excessive fine sediment and nutrient loads associated with land use practices within the catchment. Environment Southland is in the process of developing objectives for Southland estuaries with the aim to ‘maintain or improve’ estuary state, this process will explore both regulatory and non-regulatory methods.