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State of the (Birrarung) Yarra and its parklands

At a recent public conversation on the City of Melbourne’s Greenline, moderator Russel Howcroft asked the panellists how they would know if it was a success.

Dr Erin O’Donnell1 responded that people might say

~ I had a connection with the River
~ I developed an intimacy with the River
~ I got introduced to the River

Those phrases were humming along in my mind as I rode along the Yarra Birrarung this week. They tempted me off the path between Swan St Bridge and Como. Parks Victoria boat landings are the perfect place to make that connection with the River.

At first, just sitting in the quiet within the enveloping traffic noise. Then tuning in.

A pied cormorant on alert. Strands of stormwater borne plastic caught in the twigs. A Nankeen night heron under the cover of branches watching the water intently. Stormwater drains flowing into the River like a water feature.

Nankeen night heron

Enriched and energised by spending time with the River, I returned home to find the the State of the Birrarung (Yarra) and its Parklands report had been tabled in Parliament. The report is required under the legislation to be prepared every five years by the Commissioner for Environmental Sustainability.

The first report was published in 2018. In attempting to establish that first baseline, the report highlighted significant data gaps. Because if you want to manage something over time, you have to be able to measure it, as the adage goes. It was the first comprehensive status report on the Yarra Birrarung that had been prepared and it found the River wasn’t in great condition across a range of indicators.

In the five years since the last report, little has improved. Many declining trends reported in 2018 continue on a downward path. This is in spite of having legislation, supported by a plan, for the Yarra Birrarung.

The report tracks 36 indicators. I’m just going to highlight a few of the findings in this post.

Stormwater is already a grave threat to the health of the River. Stormwater flushes a cocktail of chemical pollutants into the River, and also flushes away woody debris. Stormwater will only grow as an issue in coming years as the extent of impervious surfaces grows with development in the catchment. Targets for stormwater infiltration are way off track.

Less frequent, but more intense, rainfall anticipated in climate change modelling will exacerbate the impact of stormwater on the River. Reconciling flood management with River health remains a major challenge to be addressed.

The report also finds that the negative impact of invasive species, both plants and animals, is increasing. To take just two examples: carp and sambar deer.

Carp was introduced to Victoria in the 19th century. Carp uproot and eat aquatic plants which increases turbidity and reduces light in the water column. They increase nutrients by excretion which can lead to algal blooms. Carp can survive in water quality situations too poor to support most other fish species, and can survive for several hours out of water in damp conditions. They prey on native fish and their eggs and larvae, and frog eggs and tadpoles. They also compete for space and food with water birds. Carp undermine the attempt to re-establish native fish populations.

Sambar deer are common and widespread in the Yarra River catchment and their spread is likely to continue. They have been observed as far downstream as Alphington. A study in the Yarra Ranges National Park concluded that ‘In the absence of effective deer control, commonly browsed understorey trees shrubs and tree ferns are likely to decrease substantially in cover over coming decades, potentially leading to increased light availability, drying of the understory, and increased susceptibility to wildfire.’2

They not only browse on vegetation but wallow in the mud, causing widespread damage.

The River is now protected by legislation as a ‘single living integrated entity’ from source to sea.

The health of the River and the Bay is affected by what is happening upstream.

I’ll come to the Commissioner’s recommendations another day. The Government has a year from the date of tabling the report to respond to them.

State of the Birrarung (Yarra) and Its Parklands 2023 Report Commissioner for Environmental Sustainability

2 Report by Wills et al (2023) quoted in the report above

1 Dr O’Donnell is widely recognised as an authority on the rights of Rivers. On 15 April, she gave evidence to the Yoorrook Justice Commission. The focus of water legislation and practice in Victoria has been on extracting water, water rights and entitlements. We know about terra nullius, but what about aqua nullius, is her challenge. Considering water from a cultural and environmental perspective has not been part of our historical arrangements.

All hearings of the Yoorrook Justice Commission are online.

Listen to Erin O’Donnell’s evidence to the Yoorrook Justice Commission from around 4:05

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