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Byron Shire
May 20, 2024

Effluent for Belongil Creek or a sustainable blueprint for Belongil recovery?

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David Pont

The Belongil Estuary discussion, to date, (see part one here) has raised questions about what happens next as we move towards a decision in the next year or two on replacing or upgrading the sewage treatment plant (STP), and how to manage the treated effluent after 2025. The major issue with the effluent is the increasing quantity, the daily load of water via Byron Bay’s population, and its impact on a relatively small waterway classed as an ‘intermittently closed and open lagoon/lake’ (ICOLL).

Draining floodwater. Photo supplied.

Ocean outfall – what do locals want?

Council is currently implementing a project that will further ignore the reuse option and drain effluent down a shorter flowpath to the Belongil, in spite of the legally binding Effluent Management Strategy, current until 2025, that has a primary principle of ‘sewage or effluent disposal to natural waterways or to the ocean shall be considered only as a last resort’.

How often the Belongil entrance was open before modern times, is a very uncertain thing to define but it is critical in deciding at what point the quantity of effluent becomes problematic. My sense of it is that it depended on long-term weather patterns, with the ocean wave climate and sand movement. One certainty for me is that the estuary should not be artificially opened just to let effluent out, especially in the dry season, but Council’s present drain plan makes that virtually certain. It’s already been reported the effluent is keeping the entrance open longer because of increasing volumes over the last few years with no increase in reuse.

Exploration of the issue has listed the main options for the next twenty-five year strategy as: increased reuse, dumping in the estuary or the ocean, or ‘potable reuse’, i.e. reuse back into houses. This is the normal assessment approach. They’re all difficult propositions. Much depends as well on whether the community agrees with the proposed increase in development. The 2025 effluent load will be about seven megalitres per day, but with the proposed increase of housing, that would rise to ten megalitres. How much is a megalitre? Imagine a tank of water ten metres wide by ten metres high.

The discussion can be derailed by speculation and misinterpretation where there’s a lack of clarity. My aim here is to provide an evidence-based explanation to help in achieving a sustainable solution with the least amount of conflict. The main source of information comes from the development of the current strategy twenty years ago, with the addition of recent studies. Not much of this is new, except that the current Council and the EPA appear to have abandoned the Belongil to its fate by their current pursuit of sending the effluent load via open drains in the Byron Arts and Industry Estate to the Belongil Creek and the ocean.

In that earlier phase the dumping options were rejected quickly. Farm reuse was supported, but turned out not to be practical at that time. Potable reuse didn’t make it into serious consideration, but recent developments suggest it might be looked at again.

Acid sulfate soil impact on the Belongil drains.
Photos supplied

Wetland regen

This article examines the wetlands regeneration option. The idea began with the increasing realisation that the fish kills were overwhelmingly the result of acid sulfate soil runoff (ASS), not effluent, stormwater or farm chemicals or other popular explanations.

In 1998 I was recommended by Southern Cross University to do the field work for the Byron Bay Fate of Effluent Study, sampling 27 groundwater bores, plus surface water sites. Consultants did the reporting.

After a couple of months it became clear the effluent wasn’t polluting the groundwater, so I was tasked with finding out just where it was going. I worked upstream from the lower catchment, wearing waders and carrying snake bandages. I actually needed a suit of armour against the mosquitoes that love these drains. I found an environmental nightmare: drains full of soupy red water with nothing alive except mozzies, indicating ASS. Then I came upon two small flowpaths with clear water, small native fish, mullet and eels. That was the effluent. I followed it to the STP wetlands. It was, and probably still is, the best quality water in the catchment.

The need for rehabilitation

The wetlands regeneration proposal is primarily a catchment rehabilitation project focused on bringing the severe ASS pollution under control by re-using treated effluent. ASS runoff works this way; smaller rainfalls cause the acid-generated pollutants to collect in black ooze sediments in the drains and the closed estuary. At a lower temporary opening depth of 1.0 metre under the Estuary Plan, the water flowed out at much lower velocity without picking up all the black ooze, and it deoxygenated the water (this idea was opposed later by consultant scientists who considered there wasn’t enough evidence).

We can only look at the results over many years, not just fish kills, but this opposing view would have caused some confusion in Council. As I’ve previously written, we now have a chance to see what happens; as the opening height has risen again under a new strategy.

Dead prawns in the Belongil Estuary.
Photos supplied

More than a fish kill

In some years the Belongil is affected by major floods as rain depressions dump heavy falls, usually following the hot dry spring-summer. Over several days the floods spread out across the low-lying floodplain. Salty estuarine water lapped in these zones 6,000 years ago, and have left their sulfur signature. More recent pasture grasses, and metals like iron and aluminium washed down from the catchment’s volcanic soils, combine in a cocktail that drags oxygen out of the water.

A series of chemical phenomena ensue as the still waters warm up and interact with the underlying soils. Acid and dissolved metals rise into the floodwaters, and bacteria quickly break down the pasture grasses. It also stinks with the off-gassing of sulfides as the bacterial reactions gain momentum.

As the water level falls, the extensive drains start to discharge, and the poison completely fills the estuary. Everything begins to die, right down to the entrance. Fish are gasping, dead prawns float to the surface, yabbies die in their burrows and mud crabs climb up the banks seeking air. These events aren’t just ‘fish kills’. The entire estuary is wiped out, usually until the dry spring, then the whole process starts again. Research has also found perhaps 25 per cent of surviving fish are affected by Red-Spot Disease, as the acid and metals eat away protective skin slimes. Some have no mouths, no tails or backbones.

This is why reducing the opening height was effective in preventing these events for many years. With the opening depth recently returning towards a higher 1.2 metres there’s ten times as much water which runs out at higher velocity, mobilising the sediment, while larger floods are also held in longer and turn septic.

Council has been removing fish affected by the fish kill from the river. Photo supplied.

Decoupling the catchment

In concert with the interim opening at a lower depth, the Estuary Management Plan and every document since has defined the need to ‘decouple’ the catchment from the estuary. Decoupling means a fundamental change in the drainage network on the 1,000 hectares of drained Belongil-Cumbebin wetlands, such that the soils are kept moist or wet, and floods are retained in the mid-upper catchment, as in the natural situation. It can be done with drain blocks, or preferably by filling the drains, and keeping shallow floodways near developed areas to allow big floods safely out.

Reducing CBD floods

This restoration project would not only rehabilitate what is essentially a large contaminated site, using highly treated effluent in an intermittent application cycle to regenerate the wetlands and absorb most of the effluent, but also reduce Byron Bay’s flood risk considerably. Many times I’ve seen the runoff from the western catchment drains pushing floodwaters back up towards town. Regenerating the wetlands, using a site like the proposed West Byron site, would return them to their function as a giant natural sponge, holding the floodwaters in, treating them, then letting them seep out gradually, supplying life-giving natural nutrients to the estuary.

Rejected by landholders

The science around how all this works is well established, but has been rejected by landholders. It should be understood that there’s a fundamental conflict between the landholders’ desire for dry soil in the grazing season, and the need to wet the soil to control acid generation.

I carried out much of the consultation with landholders for several years. I followed an empathetic and common sense approach, always stating ‘nobody should be disadvantaged’ in the adjustments in land use that were clearly necessary. Many times we were able to bring independent specialist scientists in to do research. We would dig up the dark soil, with landholders watching, and often it would turn red right in front of our eyes. ‘Oh, that’s why the drains are red!’. ‘Oh! That’s why the Belongil turns red and all the fish die’. 

The Belongil-Cumbebin Wetlands Restoration Strategy (2005), a Catchment Management Authority document (I was co-author), laid out a plan for rehabilitating the catchment, with practical suggestions about where the money would come from. That Strategy, with its $45k seed funding, was rejected by the Barham Council, with no explanation, but remains today the most valid blueprint for the job.

About 600 hectares of the lowlands are under SEPP 14 or other legal protection, but almost every SEPP 14 wetland has a drain either through it or around it, and is affected by acid sulfate soils. The remaining 400 hectares are agricultural, used for grazing cattle for about 3–4 months of the year. At that earlier time the average value of poor agricultural land was about $10,000 per hectare, meaning an up-front purchase cost of about $4m to buy the proposed 400 hectares outright. I think most of the landholders would have accepted it, considering this large contaminated site is virtually worthless for agriculture, and it’s unlikely these low-lying contaminated areas will ever be developed.

We know a lot about the pre-history of the Belongil from several excellent studies of ancient pollen. The lowlands once featured a mix of wetland species following the infilling of the old estuary as soil washed down onto the floodplain. Melaleuca forest, rushes and sedges and billabongs shifted around over the centuries in response to drier or wetter periods.

Stabilise the ASS

I argue for a re-creation of this ecosystem using known principles of sustainable vegetation, soil and water management, in accord with what we know about the Belongil’s history. The encouragement of native aquatic plants and wetland conditions will stabilise the acid soils. These ecosystems can be regenerated through informed water management rather than high cost plantings.

The questions around how much will it cost, and who’ll pay, need to be framed in the context of comparing it with the costs of the other effluent options. Also, with the profound question: what’s the value of an estuary full of fish?

A new STP, after Council had bought the land, could be approximately $80m. Farm reuse should be examined, but is likely to be a challenge as well. Council is spending one-and-a-half million dollars on the ‘dump it in the Belongil’ option. The costs of setting up the wetland regeneration system I suggest are roughly $2,500 per hectare for the 400 hectares; meaning about a million dollars, including project design, drainage changes, approvals, and revegetation.

The land values constitute the biggest uncertainty in the proposed regeneration project. I recommend outright acquisition and dedication as public land. The money could be sourced in a number of ways: developer charges, local contributions from sewer rates, and state government grants that would also attract federal funding – as did the first Rehabilitation Project twenty years ago.

In the Restoration Strategy we also suggested ‘development offsets’ used in similar projects elsewhere, such as a landholder might be granted for a small-scale development right for land above the floodplain, in exchange for surrendering title or use over lowland areas. This option is being implemented in Tweed Shire right now in relation to flood-prone land in an urban area. Carbon sequestration will also become more relevant as the penny drops about how much carbon wetlands can store.

My view today is that the next Council should consider moving directly to invoking the NSW Just Terms Compensation Act, an excellent piece of legislation designed for just this kind of situation where a demonstrated overwhelming public interest indicates transfer to community ownership under a fair and just process. The Act includes provision for both voluntary and non-voluntary transfer. Land values are calculated by the Valuer General.

Last, I quote for spiritual authority, the Byron land custodians – the Arakwal people, from the National Park Plan: ‘Let the creek run out into the ocean and make it clean, running, teatree water…’ During the years I was writing estuary and other management plans and consulting ‘stakeholders’ I was struck by the number of First Nations people I met who understood and talked about the tea-tree water. It inspired me to research what is actually in this complex water, and to understand that it’s full of life-giving natural nutrients.

We don’t have to be stuck in this antiquated failed system with primitive mosquito-ridden drains, saddled with acid and metals and dead estuaries; but it will take an energised community doing some thinking, coming to a conclusion, talking with councillors, followed by a concerted effort – with good scientific advice that is understandable and makes sense to everyone. ‘…Clean, running, teatree water’.

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  1. Thank you David Pont in explaining the history of the Belongil Estuary and answering my concerns for the growing amount of effluent that needs to be processed everyday by a system that is past its used by date.
    Byron’s natural wetlands of tea tree, paperbark and melaleuca habitat give us the beautiful lakes at Broken and Tallows and I hope the West Byron developments are rejected so that restoration can happen for Belongil and Byron’s population is kept to a manageable level because we are on a precipice now.


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