Southwestern Australia (SWA) is one of only 2 global biodiversity hotspots in Australia, so its rich, endemic biodiversity is already vulnerable, while fifty years of global warming has created an intensifying existential threat to freshwater ecosystems. Drying is extirpating formerly common invertebrate species in streams, causing declining alpha and gamma diversity in lakes and increasing fragmentation of populations of burrow-breeding endemic frog species. Unlike in other aridified landscapes in Australia, no drought refugia are present in SWA to protect a fauna dominated by endemic species. As natural waterbodies decline, the only perennial freshwater in the landscape is in farm dams (FD). Conventionally, FD are believed to be eutrophic, low in DO, be a haven for invasive species, be lacking native plants and have low biodiversity. We sampled 97 FD and 38 natural lakes and rivers in SWA. Water quality varied. In spring 2023, only 13% of natural sites and 9% of FD were eutrophic. Many FD supported richness of native plants, invertebrates and frogs comparable to or higher than natural waterbodies. Charophytes were diverse (13 species) and native submerged plants were present in many perennial dams, associated with high invertebrate diversity. All local species of frog that oviposit in water and several burrow-breeding frog species used FD for breeding and tadpole growth. FD supported most native species present in natural waterbodies, but also species no longer present (e.g. native gastropods). Species not supported by FD were mainly flow-dependent stream-dwelling species such as suspension-feeders (e.g. Simuliidae, Hudsonema, Cheumatopsyche), and some stream-obligate dragonflies, amphipods and Leptophlebiidae. FD are already providing dry season refuges for endemic freshwater species in SWA. The challenge now is to maximize the capacity for FD to act as refuges for native species.