Future of the Belongil and the stealthy increase in sewage capacity

David Pont

The revival of debate about how the Belongil estuary is to be managed has been sparked by Council’s plan to ‘short-circuit’ treated effluent through the Byron Arts and Industry Estate, in response to complaints by a few landholders about excess water. Many of Byron Bay’s problems involve water and are closely connected, whether acid sulfate fish kills, or stormwater flooding in the central business district (CBD), or management of the sewage treatment plant (STP) effluent.

We can begin to unpack it by first looking at some hard facts: the lifespan of the current STP and Effluent Management Strategy ends in 2025, and the need to plan for whatever comes after that means some tricky decisions in the next couple of years. Second, Council has commissioned a number of studies since 2015 that have procured an EPA licence for the new effluent pipe and drain.

40% more effluent

I’ve examined these documents and assess most of the work as capable, some very good as far as they went, but the overall approach was deeply flawed by limited briefs and a failure to deal strategically with some fundamental problems that will become clearer as time goes on. In particular, an effluent increase of over 40 per cent was quietly tacked on to the new drain.

All these recent studies support the main thrust of what was achieved in the early 2000s. Let’s look at what went down in that period in developing the current Strategy, valid until 2025. I focus mainly on the two biggest issues: the artificial opening of the estuary, and the reuse of effluent in regeneration wetlands. I point out here that my contribution to this discussion is simply as a volunteer professional witness clarifying what the community needs to start thinking about. I don’t need a job.

A little history

The Belongil Estuary Management Plan (2001) was commissioned by Council and the State government. Peter Parker and I synthesized the information and understanding from intensive research and on-ground observation of the many fish kills in the 1990s. We presented the results to the community in a practical plan for the next period, meant to be for about 4–5 years under the NSW Estuary Program. The Plan was very widely and intensively consulted and agreed by all parties. It wasn’t simply a ‘Council’ output or individual opinion.

The Plan adopted two major changes: lower the artificial opening height from 1.2 metres to 1.0 metre, primarily to stop the fish kills and stabilise the situation, and secondly make progress on addressing the major pollution impacts of acid sulfate soils (ASS) and other lesser pollution.

Ramifications

We all recognised the need for an ecology as close as possible to ‘natural’, but it was clear the Belongil, over the last 130 years, had become a highly modified place. For example, when the estuary height is at 1.2 metres or more, there’s very little space for a subsequent flood. Drainage from the CBD, already suffering from inadequate flow paths after many decades of harder surfaces and more pipes, also becomes an issue. Some have advocated stopping opening the estuary altogether, letting it rise to some notional ‘natural historic’ high level. Good luck on that one.

Some of the dangers in lowering the opening height were obvious: potential changes in the ecology over time, possibly a lower impetus to reduce Byron Bay’s overall flood risk, and my own biggest fear was that development would creep downwards, making future remediation more difficult.

There were no fish kills after 2002, until a new Opening Strategy was recently adopted, with the result that there have been two fish kills in two years. The opening height has risen again without much done about the acid sulfate drains (‘Acid sulfate drains’ is an abbreviation for the 40+ km of drains in the lowlands that dry out the peaty soils and cause the chemical reaction that produces sulfuric acid that in turn dissolves the metals, mainly iron and aluminium, that then flow into the estuary, causing a toxic soup that kills everything) so it seems the old lessons will need to be learned again. Sulfuric acid and toxic metals are being generated right now in the lowland soils, and when the La Niña rains arrive this will flow into the estuary. Also, Council’s new effluent plan will now add major flows much closer to the entrance, raising the issue of the Belongil mouth becoming permanently open just to let effluent out.

Effluent reuse

The community clearly decided in the late 1990s that reuse of effluent was far preferred to an ocean outfall or discharge to the estuary. A detailed analysis of reuse in agriculture turned up some realities, listed in Council’s current Recycled Water Management Strategy, 2017–2027: Limited irrigation in wet and cool periods; shallow water tables or unsuitable soils; and reliance on private users reduces Council’s ability to manage, adapt and maximise recycled water use. In the Brunswick Valley farm scheme, over twenty years, only eight per cent is being reused.

A rule of thumb in our region for estimating reuse demand on farms is to allow six megalitres of effluent per hectare per year. Meaning, you take the total effluent production over a year and divide by six to roughly estimate the land area required. For example Byron’s ultimate load to year 2025 of about 2,500 megalitres, divided by six means a total required area of over 400 hectares. Then there’s the massive dam needed to store the effluent for up to six months. And the pipes and pumping to move the effluent to the sites. I’ve never heard of anyone paying for effluent, so it’s all a heavy sunk cost for the community.

In response to these facts, all the people involved, on and in Council, committees and the State government took a look at trials we had set up on unused Council land near the STP, and the 24-hectare trial project evolved. It became heavily engineered with pumps and pipes, and very dense plantings leading to high set-up costs, but the Federal government provided most of the funds. We would do it differently today, using gravity flow and low-intensity regeneration methods, but the concept is proven. There would be big benefits from reusing effluent, acid sulfate control, ‘blue carbon’ sequestration, reducing the stormwater threat to Byron Bay, and others.

The wetlands have taken up 23 per cent of Byron’s annual effluent to date, but I believe this is an over estimation, amounting to ten megalitres per hectare. Urban reuse takes another 15 per cent, but this is not expected to increase. Meaning more wetlands are needed if this form of reuse is pursued. Further, I recommend a 2018 video by Martin Selecki, featuring Mayor Simon Richardson, in which the mayor offers complete and eloquent support for the wetlands solution to the Belongil problems, including expansion to 120 hectares.

Alternatives

So here we are. In summary the community needs to think about a number of questions:

• Council’s land use planners have said a 43 per cent increase in development is on the cards. Does the community want this?

• One of the issues around helping to answer this is – can the treated effluent be sustainably managed? The options include: (1) expanding the wetlands reuse scheme to at least 400 hectares for complete reuse in the catchment for the benefits explained above; (2) look at achieving more agricultural reuse; (3) an ocean outfall; or (4) potable reuse – that is, highly treated effluent for community reuse.

There are other problems to consider, such as the condition of the constructed wetlands that, in conjunction with the STP, have produced the highest quality effluent in Australia. It’s unhelpful to use terms like ‘dumping sewage’ or ‘shit’ because it undermines the credibility of the argument with the responsible authorities who know it’s not true. Issues such as the presence of viruses and endocrine disruptors should be looked at as well. Finally, how long do we tolerate the odious drains in our wetlands that are killing our fisheries, year in and year out?