The Times Australia
The Times World News

.

Floods of nutrients from fertilisers and wastewater trash our rivers. Could offsetting help?

  • Written by Michele Burford, Professor - Australian Rivers Institute, and Dean - Research Infrastructure, Griffith University
Floods of nutrients from fertilisers and wastewater trash our rivers. Could offsetting help?

The rivers running through the hearts of Australia’s major cities and towns are often carrying heavy loads of nutrients and sediments.

This is a problem. While nutrients like nitrogen and phosphorus are essential to life in small quantities, in large quantities they become destructive to river and ocean ecosystems.

When rivers are pumped too full of nutrients washing out from farms or from wastewater treatment, bacteria and algae numbers soar. We see the effects in dangerous blue-green algal blooms and in oxygen levels dropping so low that millions of fish can die, as we saw recently[1] in Menindee, New South Wales.

Fixing the problem can be expensive and difficult for landholders. That’s where a new idea could help: nutrient offsetting. Here, large wastewater plants can meet stringent requirements to keep nutrient levels low by fixing eroded riverbanks and gullies upstream, creating wetlands, and preventing fertiliser runoff. The end result: cleaner rivers.

While offsetting schemes for carbon have come under significant scrutiny[2], nutrient offsetting is a simpler market, with fewer participants and clear ways of measuring success.

Early trials in southeast Queensland by water utilities have proven it can work, as our new report[3] shows.

menindee fish kill
Poor water quality can lead to fish kills and algal blooms. AAP

Why are our rivers too full of nutrients?

In the early industrial period, rivers around the world were seen as dumping grounds, from factory chemicals to tannery waste. Since then, many countries have worked hard to clean up their waterways, with major successes including the UK’s Thames river[4].

It’s comparatively easy to stop the dumping of chemicals. You can see the pipes and pinpoint who’s doing it. But nutrient overloading is a harder problem, which is why we’re still wrestling with it.

Our cities and towns are growing. Almost seven million more people live in Australia now compared to the year 2000. As our population grows, we need more food, and we create more human waste. Our agriculture sector has also boomed and is exporting more and more food. To make our famously poor soils fertile requires fertiliser. When too much fertiliser is applied, heavy rains can wash it into rivers. Erosion on riverbanks and in gullies make the problem worse.

Read more: Would a nature repair market really work? Evidence suggests it's highly unlikely[5]

Some rivers, estuaries and coastal waters are in real trouble, such as parts of the Murray-Darling, and some urban creeks in our capital cities. We’ve hit their natural limit to handle nutrient loads and gone past it. This can cause algal blooms, fish kills and water too disgusting to drink without expensive treatment.

Erosion in queensland Erosion accelerates nutrient runoff from farms. Shutterstock

Why do we need offsetting at all?

Chemical dumping can be solved with laws and enforcement. But while we can fix degraded river catchments to reduce nutrient loads, this is rarely done. That’s because the costs are too high to be borne by any one sector, such as farmers.

By contrast, regulations on nutrients discharged by sewage treatment plants place limits of how much can be released into rivers and estuaries. The costs of further upgrades to sewage treatment plants to reduce nutrients to the required low levels is prohibitively expensive, because ratepayers would end up paying much more for water treatment.

That’s why offsetting can be useful, as it offers a win-win. Urban polluters like wastewater treatment plants can meet their regulatory requirements by restoring eroded and degraded catchment areas upstream to reduce nitrogen and phosphorus flows from farmland. Better, this can be done reasonably cheaply when done at scale. Depending on the available sites, this can be done along rivers and creeks on rural properties, or on council owned land in cities and towns.

Making this viable means using a market. Polluters looking for low-cost ways to comply with regulation of nutrient flows are linked with landholders upstream with degraded land.

This is an emerging solution, but early trials show it has promise. Population-dense south east Queensland has large waterways like the Brisbane and Logan Rivers. Wastewater plant operators such as Logan Water, Urban Utilities and Unity Water have replanted shrubs, grasses and trees along riverbanks, as well as undertaking engineering work to stabilise eroding banks.

This led to significant cost savings. Urban Utilities avoided spending A$8 million in upgrading a sewage treatment plant to cut nutrients and got the same result by spending $800,000 in erosion control and revegetation[6] upriver, which prevented five tonnes of nitrogen entering waterways. Operational costs were also much lower, saving $5 million over ten years.

Controlling erosion keeps nutrients in the soil to help crops and grasses to grow, benefiting farmers, rather than having it washed downstream. Healthier riverbanks create better habitat for birds, reptiles and mammals and makes rivers healthier for fish and other species.

What’s next?

Nutrient offsetting is still new in Australia. For it to gain traction across Australia means working to make sure the systems and science are mature.

To maximise benefits and give participants certainty, we’ll need to shift from a piecemeal trial approach to a coordinated trading scheme. Successful overseas examples typically have a third party coordinating buying and selling, and ensure there’s a robust structure to set up and assess these projects.

Canada has seen successes here, such as the South Nation River trading program[7] which has reduced phosphorus in the river, while America has examples such as the nutrient credit trading program in Chesapeake Bay. In Australia, a voluntary reef trading scheme[8] is underway in the catchments of rivers flowing into the waters of the Great Barrier Reef, involving farmers and a range of investors.

To make sure this works, we need detailed scientific knowledge on comparing nutrient pollution from different sources. Catchment runoff nutrients are mostly bound to soil particles, while sewage treatment plants have much more dissolved nutrients. As yet we don’t know how these sources differ.

We also need to know what methods of land management are best suited to stopping nutrients from washing into rivers, to ensure the best outcome for the money spent.

Creative solutions are necessary

Despite our efforts in cleaning up many of our rivers, traditional approaches haven’t been enough to stop nutrient pollution. It’s time to explore creative new approaches to make our rivers and reefs healthier.

Read more: How did millions of fish die gasping in the Darling – after three years of rain?[9]

References

  1. ^ saw recently (theconversation.com)
  2. ^ significant scrutiny (theconversation.com)
  3. ^ new report (www.wsaa.asn.au)
  4. ^ Thames river (theconversation.com)
  5. ^ Would a nature repair market really work? Evidence suggests it's highly unlikely (theconversation.com)
  6. ^ erosion control and revegetation (www.wsaa.asn.au)
  7. ^ trading program (onlinelibrary.wiley.com)
  8. ^ reef trading scheme (www.qld.gov.au)
  9. ^ How did millions of fish die gasping in the Darling – after three years of rain? (theconversation.com)

Read more https://theconversation.com/floods-of-nutrients-from-fertilisers-and-wastewater-trash-our-rivers-could-offsetting-help-203235

Times Magazine

Headless CMS in Digital Twins and 3D Product Experiences

Image by freepik As the metaverse becomes more advanced and accessible, it's clear that multiple sectors will use digital twins and 3D product experiences to visualize, connect, and streamline efforts better. A digital twin is a virtual replica of ...

The Decline of Hyper-Casual: How Mid-Core Mobile Games Took Over in 2025

In recent years, the mobile gaming landscape has undergone a significant transformation, with mid-core mobile games emerging as the dominant force in app stores by 2025. This shift is underpinned by changing user habits and evolving monetization tr...

Understanding ITIL 4 and PRINCE2 Project Management Synergy

Key Highlights ITIL 4 focuses on IT service management, emphasising continual improvement and value creation through modern digital transformation approaches. PRINCE2 project management supports systematic planning and execution of projects wit...

What AI Adoption Means for the Future of Workplace Risk Management

Image by freepik As industrial operations become more complex and fast-paced, the risks faced by workers and employers alike continue to grow. Traditional safety models—reliant on manual oversight, reactive investigations, and standardised checklist...

From Beach Bops to Alpine Anthems: Your Sonos Survival Guide for a Long Weekend Escape

Alright, fellow adventurers and relaxation enthusiasts! So, you've packed your bags, charged your devices, and mentally prepared for that glorious King's Birthday long weekend. But hold on, are you really ready? Because a true long weekend warrior kn...

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Times Features

Prefab’s Second Life: Why Australia’s Backyard Boom Needs a Circular Makeover

The humble granny flat is being reimagined not just as a fix for housing shortages, but as a cornerstone of circular, factory-built architecture. But are our systems ready to s...

Melbourne’s Burglary Boom: Break-Ins Surge Nearly 25%

Victorian homeowners are being warned to act now, as rising break-ins and falling arrest rates paint a worrying picture for suburban safety. Melbourne residents are facing an ...

Exploring the Curriculum at a Modern Junior School in Melbourne

Key Highlights The curriculum at junior schools emphasises whole-person development, catering to children’s physical, emotional, and intellectual needs. It ensures early year...

Distressed by all the bad news? Here’s how to stay informed but still look after yourself

If you’re feeling like the news is particularly bad at the moment, you’re not alone. But many of us can’t look away – and don’t want to. Engaging with news can help us make ...

The Role of Your GP in Creating a Chronic Disease Management Plan That Works

Living with a long-term condition, whether that is diabetes, asthma, arthritis or heart disease, means making hundreds of small decisions every day. You plan your diet against m...

Troubleshooting Flickering Lights: A Comprehensive Guide for Homeowners

Image by rawpixel.com on Freepik Effectively addressing flickering lights in your home is more than just a matter of convenience; it's a pivotal aspect of both home safety and en...