How many councils does it take to save the Hawkesbury River?

The Hawkesbury River had a time of it during the 1980s and 1990s — faulty wastewater treatment, urban runoff, dead fish, toxic algal blooms.

It was only following advocacy by grassroots community groups and the local council that conditions have significantly improved over recent decades. 

But now, with the pressures of increased development and rising sea levels, local councils and environmental scientists are again working out how we can keep the river clean and healthy.

How does this happen? 

A Coastal Management Program (CMP) is the first step in preparing coastal regions for the impacts of climate change. 

It broadly assesses the Hawkesbury River’s health, examining past, current and future hazards — pollution, flooding, erosion, algal blooms — and what needs to be done to avoid these. 

The Hawkesbury-Nepean River System CMP, led by Hornsby Council, is currently the largest in NSW.

Tim Macdonald, an environmental scientist who has worked along the Hawkesbury for decades, is helming Hornsby’s input to the CMP.

Work on the program has identified two major issues: development and climate change. 

Macdonald told the Lorikeet that increased urban development across councils like Hornsby and the Central Coast will likely mean more runoff into the river. This runoff — heavy metals, litter, oil and nutrients — has a direct negative impact on water quality.

Rising water levels are one impact of climate change being assessed. Maps are being redrawn and flood plans reassessed based on how high scientists project our tides will climb.

The issue of temperature is equally significant, as warmer waters correlate directly to algal events. This would only be exacerbated by increased nutrients for algae to feed on washing in from increased flooding. 

Among risks to the river, toxic algal bloom events similar to those observed in South Australia are a major concern.

Why does it matter?

Water quality of the Hawkesbury doesn’t just matter to those living directly along the river, but to the large, diverse industry operating along it. 

Oyster farmer James Brown told the Lorikeet recently that strict quality control in the industry meant tiny changes to water salinity or temperature could halt harvesting. 

Alongside mollusk farmers and fisheries, the Hawkesbury is a magnet for tourists.

What can be done?

In Australia, much of our larger response to climate change — reducing net emissions, investing in clean power — lies with the federal government. Macdonald accepts that councils only hold a limited amount of power.

“All levels of government, everyone plays a role, but from a local council perspective … how do we manage the known impacts of climate change, that aren't going to change quickly and are happening already?”

He said there is still much councils can do, working in collaboration with the state, to adapt to looming climate impacts. Some measures looked at in the plan include:

• Increased water monitoring and early warning systems for algal bloom events
  

• Upgrading the sewerage and stormwater infrastructure of surrounding suburbs
  

• Rehabilitating wetlands and mangrove forests, which can act as natural bulwarks against flooding, pollution and erosion 

Beyond Hornsby: The CMP is collectively organised by Hornsby, Ku-ring-gai, Northern Beaches, Central Coast, Hills and Hawkesbury councils. The NSW government funds two-thirds of the project.

One councillor involved in the project told the Lorikeet reaching consensus between six councils presented somewhat of a challenge. Still, after years of planning, they have agreed for the CMP to go on public exhibition.