Fire and water in the Blue Mountains : lessons from a long term monitoring program

The Australian bushfires of summer 2019-20 had drastic impacts on catchments and waterways that are yet to be fully understood. Seventy-one percent of the Greater Blue Mountains World Heritage Area (GBMA) was affected by these fires. To date, much of the research on the impact of fires has focused on catchment hydrology and physical water quality. Less is understood about impacts on aquatic macroinvertebrates, and hence the ecological health of waterways post-fire. This paper analyses long-term data from Blue Mountains City Council's aquatic monitoring program, to assess the impact of the bushfires on headwater streams in the GBMA. We compare the macroinvertebrate community, waterway health ratings, and basic physical water quality parameters pre-fire and post fire, at sites with over twenty years' of data. The results from this research showed that the stream invertebrate communities displayed a much higher degree of resilience to bushfire than was expected. Some measures of stream ecological health were actually higher at more recently burnt sites. The need for management that builds the resilience of waterways with urban catchments is emphasised by these results, as well as the value of long term monitoring programs. This contributes to a growing body of research on fire impacts, building capacity for adaptive management in the Blue Mountains area and beyond.