South Africa's flagship assessment of the state of biodiversity and ecosystems, produced approximately every five years by SANBI in collaboration with numerous research institutions and government departments. First assessment in 2004 (National Spatial Biodiversity Assessment), followed by NBA 2011, NBA 2018, and NBA 2025. The NBA assesses the status of species and ecosystems across five realms: terrestrial, freshwater (inland aquatic), estuarine, coastal, and marine. Key freshwater findings from NBA 2018: 64% of river ecosystem types are threatened (22% Critically Endangered), 65% of wetland ecosystem types are threatened, freshwater fish are the most threatened vertebrate group in South Africa. Drivers of freshwater ecosystem decline: flow modification (dams, abstraction), habitat degradation, pollution, invasive species, and overexploitation. The NBA informs national conservation priorities, spatial planning, environmental authorisation, and international reporting obligations under the CBD, Ramsar Convention, and SDGs. NBA data supports evidence-based policy-making and compliance monitoring.