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Council’s annual report card on water quality in the Tweed has just been released and residents are invited to view the results via a new online interactive tool.
As well as providing a summary of water quality from the creeks and rivers across the Tweed, the online platform allows the audience to view the report, images, videos and graphs in a strikingly laid out and interactive medium.
The waterway report card scores are based on data collected between April 2020 and May 2021, a period characterised by higher than average rainfall in the Tweed.
Council’s Waterways Program Leader Tom Alletson said this year’s report asked the Tweed community what they valued in their waterways and what they looked for when evaluating waterway health.
“While Council measures water quality with scientific instruments and compares it to targets set by the NSW Government, we know the average person is not considering turbidity or milligrams per litre of total nitrogen when they look at their environment,” Mr Alletson said.
“Year to year and week to week, rainfall is the biggest influence on water quality in our creeks and rivers. While Council is delivering a significant amount of work that is restoring the environmental health of our waterways, water quality benefits are likely to be achieved and measured across decades rather than years.”
Key findings indicate the lower parts of the Tweed River – from the ocean up to Stotts Island and to Terranora/Cobaki Broadwater – have good water quality, scoring an ‘A’ on the report card.
The tributaries of the Cobaki and Terranora broadwaters are showing poorer water quality, scoring a ‘D’ and reflecting low tidal flushing and the impacts of degraded creek banks. These 2 factors also affect the Rous River, which scores a ‘C’ and shows high levels of the nutrients nitrogen and phosphorous.
The freshwater reaches of the river upstream of Murwillumbah have moderate water quality, scoring a ‘B’ on this year’s report card. The single biggest issue that affects water quality compliance in the upper catchment is the high level of phosphorus detected in water samples. While this is expected in the waters of a settled catchment, it is also likely to be related to the rich volcanic soils of the upper Tweed Valley.
Mr Alletson said the only change of grade in this year’s report card is of the combined Tweed coastal creeks, dropping from a ‘B’ to a ‘C’ in 2021. This is due to samples showing non-compliance for bacteria, pH (acidity) and nitrogen.
“We know there are acid sulphate soil problems in the floodplains of both Cudgen and Cudgera creeks and this, combined with higher than average rainfall, has resulted in low pH runoff,” Mr Alletson said.
“High flows also lead to elevated bacteria levels at times. In 2022, Council will undertake more research to trace the source of bacteria which is being identified in Cudgera Creek, particularly within its upper reaches.
“We have ruled out human sources for the bacteria, however we are considering the use of a technique that can collect and match the DNA of animals in waterways to determine its source.
“Given the Tweed’s coastal creeks typically have healthy bushland habitat on their banks and livestock in their catchments, the bacteria found is likely to be a combination of native animals and domestic species such as dogs and cows.”
Samples undertaken over recent weeks, before the heavy rain in late November, showed full compliance with water quality targets for swimming at the mouths of all 3 coastal creeks. However, it is expected water quality will have declined with high rainfall flows in recent days.
“Water quality changes throughout the day with tide, and from week to week with rainfall and across wet and dry years,” Mr Alletson said.
“People should exercise caution when swimming in creeks or rivers that are turbid and affected by runoff.”
View the water quality report and online interactive tool at tweed.nsw.gov.au/rivers-creeks.
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