This dedicated e-newsletter has been established to keep community updated on information and actions relating to the health of the Curdies River and tributaries.
Please forward to your networks.
Happy New Year and welcome to the first Curdies community update for 2023.
Deakin University have released the results from their 2022 Curdies River Nutrient Enrichment Study. Below we provide an overview of the results as well as links to where you can find the full report. The Curdies River Consultative Committee will meet in February to discuss the results and determine next steps in response to the recommendations. We will keep you updated following the meeting.
We’d like to say thank you to those who attended our recent Fish Hotel & Citizen Science event in Peterborough. Participants learned about our fish hotel program in the Curdies Estuary and got to be citizen scientists for the day – see the full story below.
We’d also like to make you all aware of an upcoming event you can sign up for, Sustainable Dairies Workshop including Fert$mart, an invaluable learning opportunity for all farmers. Read on to find out more about the event and to sign up.
Table of contents: click the links to jump to each story
Investigating Sources of Nutrients in the Curdies River
Deakin University researchers have released their final report in the Curdies River Nutrient study. Below we provide you with a brief description of the study and why it has been conducted, an executive summary as well as the key findings.
The full report can be found here: Investigating the sources of nutrients in the Curdies River
Analysis of water quality data from 1990 to 2005 was presented in a 2005 report (Applying an Ecological Risk Assessment process to investigate nutrient enrichment in the Curdies River Catchment, 2005) prepared for the Corangamite Catchment Management Authority (CCMA), the Victorian Department of Sustainability and Environment (DSE) and the Victorian Department of Primary Industries (DPI).
The 2005 report found that phosphorus concentrations in the Curdies River regularly exceeded State Environment Protection Policy (SEPP) triggers and that phosphorus and nitrogen concentrations, and turbidity increased at high-flow periods, especially during winter and spring. The 2005 report gathered substantial data, with the aim of identifying the risk of elevated nutrient levels on ecological and other values of the Curdies estuary over the following decade. The report also provided several recommendations for management and monitoring and advised that, without substantial action, in addition to other factors, ongoing eutrophication (excessive nutrient enrichment) meant that the risk of cyanobacterial blooms occurring in the future was high and posed a substantial risk to ecological values of the estuary.
Since the 2005 report was completed, this risk has been realised. Cyanobacterial blooms have now occurred a number of times in the Curdies estuary, culminating in a major bloom in early 2022, which resulted in fish deaths. Understandably, these events have resulted in increasing community concern and highlighted the need for action to address the underlying factors that have led to the Curdies’ current condition.
In this report, we review data from the 2005 report, in addition to data collected since that time, to investigate whether and how patterns of nutrient concentrations have been affected by management strategies implemented for the Curdies River catchment, including those implemented in response to the 2005 report. We also review and update the conceptual models presented in that report and the recommendations it presented relating to cyanobacterial blooms and eutrophication. Our aim is to provide management authorities with information to inform decisions and strategies into the future and to provide the community with information about the health of the Curdies River and estuary.
EXECUTIVE SUMMARY OF CURRENT STUDY
A major bloom of toxic cyanobacteria (commonly referred to as ‘blue-green algae’) in the Curdies River Estuary in early 2022 raised considerable concern in the local community about the health of the Curdies River system.
Cyanobacterial blooms occur when environmental conditions occur that favour cyanobacteria over other photosynthetic organisms, such as algae. Cyanobacterial blooms are increasing in frequency, severity and extent worldwide. A major cause of this increase is an increase in important nutrients in waterbodies, especially of phosphorus and nitrogen, in combination with changes in climatic factors.
Monitoring data collected for the Curdies River system since the 2005 Ecological Risk Assessment indicate that eutrophication continues to be of major concern. Concentrations of the key nutrients phosphorus and nitrogen regularly exceed Environmental Reference Standard objectives in the upper reaches of the Curdies River. It is likely that they are, likewise, exceeded in the lower catchment and estuary, although direct monitoring of nutrient levels in these segments of the system is unavailable. Whilst mitigation measures instituted since 2005 appear to have reduced concentrations of phosphorus under low-flow conditions, concentrations of phosphorus under high-flow conditions have not decreased and concentrations of nitrogen have increased.
In the upper reaches of the Curdies River catchment (the upper Curdies and Scotts Creek subcatchments), high concentrations of phosphorus and nitrogen are strongly associated with high turbidity. This association suggests that high nutrient inputs are likely to be a result of erosion or other processes, or factors associated with current or past farming practices that contribute sediment and nutrients simultaneously. An example of such a source is sheet runoff from pastures. Monitoring data also indicate that the majority of nutrients enter the system and migrate down it during the high-rainfall period between June and October. The Scotts Creek sub-catchment contributes more nutrients to the system than the upper Curdies subcatchment, likely because of its steeper topography. Dairy farming is likely to be a major source of these nutrients to the catchment, due to its predominance over other land uses in the Curdies River Catchment and because data suggest diffuse (spread over a large area), rather than point, sources of nutrients.
To address high nutrient levels in the Curdies River catchment, strategies should be put in place to reduce nutrient loads entering the system. Surveys should identify major sources of nutrients inputs (especially in the Scotts Creek sub-catchment). In particular, key locations should be identified where nutrient reduction strategies, such as constructed wetlands and riparian revegetation, are likely to have the largest effect. Long-term monitoring of nutrients in the lower Curdies sub-catchment and in the Curdies Estuary should be undertaken to assess the nutrient contributions and loads present in those areas, and so that the success or failure of management strategies can be accurately assessed.
Whilst there are many opportunities for improvements that could, over the long-term, reduce nutrient concentrations throughout the Curdies River catchment and estuary, high levels of nutrients in the sediments of the estuary, river and in the soils of the catchment as the result of historic and current practices mean that ecological benefits, including a reduction in the incidence of cyanobacterial blooms, may take decades to become apparent.
Recommendation 1: Management strategies put in place to address nutrient enrichment in the Curdies River catchment and estuary should incorporate clear goals and targets so that their effectiveness can be assessed. These goals need to consider that there are high levels of nutrients in the sediments of the estuary and river and in the soils of the catchment that are likely to continue to fuel cyanobacterial blooms for years to come. Targets should be clearly articulated, be achievable and should have clear criteria for success or failure. Management strategies should focus on reducing the amounts of nutrients entering the system over the long-term.
Key Recommendation 2: Baseline monitoring be conducted to gather more information and provide a more holistic picture of the current health of the river system. Monitoring should include assessments of the nutrient loads of the estuary and the lower Curdies catchment. Ongoing monitoring to assess whether targets are being achieved should be viewed as an essential element of the management program.
Key Recommendation 3: A nutrient reduction program should be implemented for this catchment to lower the levels of nutrients entering the Curdies River system. Monitoring and surveys should be conducted to identify the most important nutrient transport pathways that should be targeted for management. The major focus of the management effort should be invested in addressing diffuse source nutrients from grazing land.
Key Recommendation 4: As a first step in launching the management program, the community and the various land and water management agencies in this catchment need to review these targets and clearly state whether they support them. A coordinating body should be established to ensure that any planned actions can be organised among responsible management organisations as a unified strategy.
Key Recommendation 5: To the extent that it is practicable, monitoring and/or estimation of land-use changes and other key factors in the Curdies catchment should be incorporated as part of an adaptive management program, so that information provided to landholders, management strategies and assessments of strategies’ success or failure can take these factors into account and can be adapted as they change.
Key Recommendation 6: Extension programs should be specifically designed and implemented to continue improving nutrient management practices, and should highlight both economic and environmental benefits. These should be frequently updated in the light of new research.
The full report can be found via the Corangamite CMA website HERE. The full report also contains community questions and answers and a series of case studies on blue green algae management.
Fish Hotels - A great place to stay if you are a fish!
Fish hotels provide habitat for aquatic wildlife including fish, frogs, water rats, insects and birds. As part of the 2023 Summer by the Sea program run by Coastcare Victoria, the Corangamite CMA hosted a fish hotel education experience in Peterborough.
Participants were able to see a typical fish hotel, that has been installed in the Curdies River estuary, as well as learn about the EstuaryWatch program and how people get involved in water quality monitoring at Peterborough.
Attendees were a scientist for the day, learning to use water testing equipment to measure oxygen and salt levels in the Curdies River estuary.
The education sessions finished off with a craft activity were participants created their own fish hotel.
A fun day was had by all!
Event participants create their very own (mini) fish hotels
Summer by the Sea is brought to you by Coastcare Victoria, in collaboration with a range of activity providers and community groups.
Fisheries Habitat Restoration Program
In 2022, thirty-two new fish hotels were installed into the Curdies Estuary providing habitat for aquatic wildlife, including angling species such as Black Bream and Estuary Perch, frogs, water rats, insects and birds. This is part of the Australian Government’s ‘Fisheries Habitat Restoration Program’.
The fish hotels are built from locally sourced eucalyptus designed as shelter and feeding sources for fish species.
A fish hotel ready to be installed
The Curdies Estuary fish habitat restoration project is being delivered in partnership between the Corangamite Catchment Management Authority, OzFish Unlimited and VRFish. The project also includes riverbank protection and revegetation works and angler planting days.
Members of the public are invited to come to the Curdievale boat ramp on Saturday 4th March to see a demonstration of the electrofishing process and hear a talk about Curdies River fish. Watch our Facebook page for more details and timing.
Having been installed in August 2022, it is now time to survey the fish hotels hotels to see if they are being used by fish. Dion Iervasi from Austral Research and Consulting will conduct electrofishing at various sites along the Lower Curdies River, between Curdievale and the top of the estuary.
From his boat, Dion will put an electrical charge into the water which will stun any fish using the fish hotel as habitat. The fish will be weighed and measured. The data collected will be used to compare the numbers and types of fish using that part of the river with the numbers present when the first survey was conducted, back in June 2021 before the fish hotels were installed.
This project is supported by Corangamite CMA and funded by the Australian Government.
Sustainable Dairies Workshop including Fert$mart
Brought to you by WestVic Dairy, Agriculture Victoria and the Corangamite Catchment Management Authority, this four day course is held over three months, including a field day at the conclusion.
Participants will complete a Fert$mart course, which includes five soil tests and a comprehensive nutrient management plan, and will also receive an Effluent Use Plan.
New program start date:
Tuesday 31st January
10.45am - 2.15pm
Please contact Libby on 0459 612 681 for further information.
Many farmers find that when they get soil and fertiliser management right, they can produce more feed at no extra cost. With careful planning, fertiliser becomes a strategic tool to boost feed when it is most needed, whilst ensuring there are minimal nutrient losses to the environment.
Fert$mart provides farmers and advisors with a planning approach and the know-how to achieve this.
The Fert$mart planning approach aims to better match nutrient applications to pasture and crop nutrient requirements, allowing dairy farmers to save money on fertilisers without reducing production. Using the Fert$mart approach, nutrient application can better match the right product at the right rate at the right time and in the right place.