Live Oral Presentation in person as part of National Virtual Conference AFSS Conference 2020

Water quality impacts of the 2019-20 bushfires in the Upper Murray catchment (#7)

Klaus Joehnk 1 , Tapas Biswas 1 , Anu Kumar 2 , Fazlul Karim 1 , Scott Wilkinson 1 , Juan Guerschman 1 , Gavin Rees 3 , Paul McInerney 3 , Petter Nyman 4
  1. CSIRO, Canberra
  2. CSIRO, Adelaide
  3. CSIRO, Albury
  4. Alluvium Consulting, Cremorne

The ‘Black Summer’ bushfires of 2019/20 burnt significant portions of agricultural and forested land in the upper Murray River catchment in south-east Australia. CSIRO undertook a pilot study in the main channel of the Murray River during and after the bushfires to assess impacts on aquatic ecosystems and to explore potential solutions for both short- and long-term deterioration of water quality. Heavy rainfall events immediately after fires in severeley burnt catchments produced large increases in sediment loads and increased the concentration of pollutants (ash, nutrients, organics and metals) that degraded local water quality and threatened water quality in downstream Lake Hume. Short-term effects were readily visible by the black colour and the media reported “cake-mix” viscosity of the water and localised fish kills. Medium to long-term impacts are less clear and require continued monitoring across extended temporal and spatial scales.

Here, we present a synthesis of our key findings from our pilot study, focussing on fire severity maps, changes in streamflow, sediment and nutrient loads, water quality and ecotoxicity responses. Information generated from this study provides a valuable basis for future research direction to support bushfire-related research effort and policy development in catchments across Australia.