Waterway health: bushfires, floods take a toll

Published on 22 October 2020

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MidCoast waterways have been impacted from the 2019-2020 season of extreme events, with the release of the 2020 Waterways and Catchment Report Card showing a decline in some areas.

“The 2019-2020 monitoring period was one of extreme climatic conditions including drought, bushfires and flooding all of which can have a significant effect on water quality and that was reflected in the results. A total of nine sites tested dropped a grade when compared to the previous year with the remaining nine sites maintaining their grade,” said Dr Peter Scanes from the NSW Department of Planning, Industry and Environment (DPIE).

Fire is an intrinsic part of the Australian environment, and often used for ecosystem management. However the 2019 fires that took place on the MidCoast were extreme and had devastating impacts on our community, wildlife and environment. 

"Due to the moderate and heavy rainfall that followed the fires in January and February it is difficult to differentiate the changes in water quality due to the bushfires from the flooding that followed them, but from the results we can see they both had an effect," said Dr Scanes 

Increased levels of algae in our waterways had the biggest impact on the results this year, with 14 of the 18 sites sampled showing an increase in algal levels. This result indicates there was an increase in nutrient runoff during the rains early in the year, particularly evident in the fire-affected sites of the Manning, Khappinghat and Wallamba, as well as in the Karuah and The Branch Estuaries. Many sites also saw a reduction in water clarity after the rains.

Each year, MidCoast Council partners with scientists from the DPIE to independently assess the health of our waterways as part of the Waterway and Catchment Report Card. "These results help us keep track of the effectiveness of the many water quality projects we undertake each year with our community and partners," says Council’s Water Quality and Estuary Coordinator, Prue Tucker.

“Waterways are an important part of our region, contributing significantly to our economy and tourism, and providing us with a beautiful natural environment in which we live.

“We’re invested in a waterway health program and in monitoring water quality across our region to protect our important waterway assets.”

This year’s Report Card results were revealed during a free livestreamed event on Thursday 22 October, with over 60 participants joining the event.

A number of scientists shared the results of studies and projects taking place across the MidCoast region, highlighting that good science underpins management of MidCoast waterways.

"The evening was a great success, it was great to see so many people join us to learn more about the role scientific study plays in catchment management," said Prue Tucker.

In the coming weeks Council is hosting a number of other free livestreamed events to allow residents to connect with our waterways and the science behind them.

To book in for these events or view the report card go to the link above. Hard copies of this year's Waterway and Catchment Report Card are also available from MidCoast Council. 

Snapshot view: The 2020 Waterway Report Card results

  • In estuaries there is always the potential for algal growth it just grows better in some conditions (high temperatures and lots of light improve the ability to utilise excessive nutrients). Due to the changes in conditions from drought to flood during 2019/20 there was an increased ability for algae to grow particularly in lake estuaries.
  • Half of the tested sites (9) dropped by a grade from the 2018/19 results, the remainder (9) remained at the same grade as 2018/19.
  • The only location to receive an good (A)  grade this year was Myall Lake.
  • Karuah River and The Branch Estuaries remained at fair (C) grades.
  • Khappinghat Estuary remained at a C grade the same as in 2018/19; this is unusual though as ecological condition of the area is expected to be excellent.
  • Wallamba Cove dropped from a B to C; this was driven by water clarity results indicating that there is still an issue with sediment runoff coming from urban area in Tuncurry. 
  • In the Manning we saw a drop in grade from good (B) to fair (C) in the Upper Manning and Dawson River Estuaries, while the Mid and Lower Estuaries and Farquhar Inlet retained their good (B) grade.
  • In Wallis Lake, the Mid Wallamba Estuary retained its fair (C) score while all other sites dropped a grade.