New Deakin University report sets out how to save the Curdies River

A long-awaited Deakin University report into the causes of deadly algal blooms in the river was published in late January, presenting six "key recommendations" to bring the waterway back from the brink

The Corangamite Catchment Management Authority (CCMA) commissioned the study in mid-2022 after an unprecedented outbreak of blue green algae in the lower reaches of the Curdies wiped out tens of thousands of native fish and other aquatic life, triggering a desperate, angry community outcry.

The report maps a decades-long history of environmental degradation bringing the catchment to its current condition, along with the contemporary practices that continue to damage the waterway, and sets out a clear plan to resurrect the river.

But one of the key reference points for the new report is a 2005 Ecological Risk Assessment of the Curdies, also commissioned by the CCMA, which points out nearly identical issues, foreshadows potentially devastating algal blooms and sets out nine "key recommendations" that would avert disaster.

Subsequent events have shown disaster wasn't averted - by many measures the river is as sick as it's ever been - and almost none of the recommendations in the 2005 study were implemented in a substantial way, which raises the question: will it be different this time?

The land around the Curdies catchment has been home to the Girai Wurrung people for thousands of years, but it wasn't until white settlers arrived to the area in the 1840s that the landscape began to change.

The perfect pastoral conditions prompted waves of agriculturalists to take land from Cobden down to Peterborough and start ripping out the native forest to make way for paddocks.

The process steadily accelerated through the 20^th Century, particularly during the Heytesbury Soldier Settlement Scheme between 1960-1976, so that by 2003 less than six per cent of the native forest in the region was left standing.

Since the late 1980s there has been very little land use change, but 83 per cent of the land has become "exotic pasture" and for the river system it has been catastrophic.

The loss of trees and native shrubs has meant that the naturally abundant rains wash much more soil and sediment into the river system than before. But just as important as the sediment are the chemicals, or "nutrients" which also enter the river and are either washed downstream or settle into the silt of the riverbed until the next downpour.

The 2005 study noted problems with the river water in the Curdies were already clear in the early 1990s. It showed results from a testing gauge in the river where concentrations of phosphorus were breaching State Environment Protection Policy trigger levels every single year from 1990, and were sometimes eight to 10 times above the trigger point.

Both the 2005 and 2022 Curdies studies singled out phosphorus and nitrogen as the key threats to the current and future health of the river system.

The two nutrients are the vital elements, along with sunlight, for blue green algae to grow. They are also key nutrients used by dairy farmers on their pastures, primarily to fertilise the grass to grow faster and more abundantly.

The 2005 study warned algal blooms were the main risk to the river, both at the time and over the following 10 years or more. It also said the huge amount of nutrient already lying in the river sediment needed "to be considered when setting realistic management goals" to fix the river.

Among the nine recommendations in that study were stopping new nutrients from entering the river system, baseline monitoring of the river water and riparian vegetation, nutrient reduction programs targeting dairy farms to change harmful farming practices, and setting clear targets to assess the success of the interventions.

In the following 17 years the government and CCMA have installed water monitoring gauges, started community citizen science programs, dairy farmer education programs, and riparian and aquatic restoration programs. But most of the 2005 recommendations haven't been substantially implemented and the nutrient levels haven't been curbed.

The Standard asked the CCMA why so many of the recommendations in the 2005 report hadn't been implemented. A spokesperson said "while some recommendations had progressed, some were not realistic or feasible".

The Deakin report reviewed a number of targets set in the 2005 study regarding nutrient and phosphorus levels in the river. It found the targets "have either not been met... were not able to be assessed due to identified minimum monitoring requirements not being undertaken... or can be shown to have not been met, despite minimum monitoring requirements not being undertaken".

It also assessed the management strategies set out in the previous study, judging the fencing and riparian restoration process a success because it had protected 30 per cent of the catchment's 330km of "named waterways". Although it noted there were an additional 1200km of "unnamed waterways" where the existence of fencing was unknown, meaning a significant majority of the catchment was unprotected.

The Deakin study said the repair work appeared to be improving some of the nutrient levels at particular times, with phosphorus levels decreasing slightly since 2005 under low flow conditions.

Unfortunately the report also found phosphorus levels under high flow conditions had increased over the same time period in the Scotts Creek sub-catchment and remained steady in the Upper Curdies section.

The report also showed high flow conditions - during the wet period from June to October -were when the vast majority of the total nutrient load entered the waterway, meaning arguably the most successful intervention in the river over the past 17 years had not led to a reduction in the overall nutrient quantities in the catchment.

Lead researcher for the Deakin report Professor Rebecca Lester said anecdotally stocking rates in the region had risen over the period, so it was possible nutrient levels would have risen without the various intervention measures.

The report repeated the 2005 advice that strategies were urgently needed to stop more nutrients entering the system. It also repeated the recommendation that any goals be "clearly articulated", "achievable" and "have clear criteria for success or failure".

Professor Lester said she and her colleagues were instructed to review the 2005 recommendations, which was why the new recommendations were so similar, with the researchers warning that there were already enough nutrients in the river sediment to produce algal blooms for decades, even if practices like the widespread use of fertiliser were to stop overnight.

After the major bloom and fish kill in autumn 2022, the CCMA created a consultative committee composed of government bodies like the Environment Protection Authority and Department of Energy, Environment and Climate Action, along with dairy industry representatives, Indigenous groups and concerned locals.

At its next meeting on February 22 the committee will discuss the report and how its recommendations could be implemented.

The single-biggest contributor to new nutrients entering the Curdies is dairy farming, with rain continuing to wash fertiliser into the river. The CCMA runs a Sustainable Dairies program to teach farmers how to move away ecologically damaging chemicals, but it has changed practices in just a small fraction of the dairy farms in the region.

The Standard asked whether new nutrients could be stopped without much greater investment and co-operation from farmers and the dairy industry. A spokesperson said the CCMA would "continue to work with farmers and the dairy industry via the Curdies River Consultative Committee".

"The Sustainable Dairies program is just one part of the equation. Some dairy processors also work with their farmers on Environment Management Plans, and the EPA has undertaken compliance inspections of a subset of farmers and found that the level of compliance was high with the farmers inspected."

The EPA compliance program aimed to audit 450 farms across the region. After nearly a year it has spent three days auditing 25 farms, with two found to be breaching environmental regulations by allowing effluent to pour into the river.

Consultative committee member and president of the Curdies River Catchment Alliance Barb Mullen said the next step would be crucial.

"Will this report actually make anything different?" she said. "What difference will it make to the river?"

Given the most significant 2005 strategies were ultimately shelved as "unrealistic", The Standard asked the CCMA whether there was sufficient funding and political will to implement the new suite of recommendations.

A spokesperson said the CCMA "will work with the consultative committee to identify the most feasible and effective options for future river management".