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Byron Shire
September 22, 2021

How does your toilet flush affect the Belongil Estuary?

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Byron Shire Council are looking to overcome waterlogging of farmland caused by treated effluent from the Byron Sewage Treatment Plant (STP), by diverting excess effluent via a shorter route through the Arts & Industry Estate to the Belongil Estuary. This appears to be a prelude to upgrading the STP. Doing the flowpath project under the infrastructure SEPP, Council are not required to investigate all environmental impacts, alternative options, or engage with the community. Here David Pont continues to explores an alternative…

Part one: Future of the Belongil and the stealthy increase in sewage capacity

Part two: Effluent for Belongil Creek or a sustainable blueprint for Belongil recovery?

David Pont

The Belongil STP ideas advanced by State Member Tamara Smith and Cr Coorey add interesting points to what I’ve put forward in recent articles. We need progress in the discussion if the community wants a sustainable solution to the Belongil problems. With that contribution we are beginning a community assessment, with ideas and concepts put forward, followed by looking at the advantages and constraints of each. A formal assessment process will follow in future, but now is the time for ideas. The complexity means an effluent project must be decided based on best knowledge, what’s practical, and possible, in the landscape.

In broad-scale water management a fuller understanding of the land’s shape helps because water runs easily downhill, and it’s expensive to pump uphill.

Council collects sewage from the houses, and pumps it to the STP for treatment. The excess treated effluent must re-enter the environment by spreading out again. The current short-circuit drain project uses a small estuary to spread it out. I propose that it be spread out to the maximum possible, evaporated, and naturalised through large wetlands.

Mud map of Belongil. Image David Pont.

Restoration opportunity

The ‘mudmap’ (above) shows a broad layout of how water runs (arrows) to the Belongil Estuary, along with the general soil types. The map shows acid sulfate soils (ASS) in yellow to describe the old estuarine areas with mangrove muds and peat, with a little sand, and a general surface elevation below about 2.4 metres above sea level, and a geological age of about 8,000 years to the present – so fairly recent. Owing to the prevalent ASS, my view is that these lands, currently used for low-value grazing, should pass to public ownership and be rehabilitated.

The delineation of these high-risk ASS areas that are cleared and drained, and are suitable for restoration, needs to be done through detailed planning. In general there may be about 400 hectares possible, both north and south of Ewingsdale Road, and around towards Skinners Shoot. The task is to map areas below about 2.4 metres elevation, then work through the constraints around wetlands protected by legislation. It has been considered in detail in the past and the constraints won’t be a block.

There will be little need for any backfill or substantial construction – in fact there will be as little disturbance as possible. The drains could be reshaped so the soil is no longer dry, and the floodplain will revert to its natural function of storing floodwaters.

The West Byron development site, along with Sunrise and the A&I Estate is, in contrast, on the coastal sand plain. Most of it has a general elevation above 3.3 metres, with an age of at least 125,000 years; when the sea level was higher and sand dunes were deposited. These old dunes were levelled during sand mining in the 1960s, leaving the plain of today. ASS presence is negligible there.

Consider the drive from Ewingsdale into the Bay. Past the hospital, up through the cutting, and the vista opens to Byron Bay, crowned by the lighthouse.

We descend quickly from the cutting to the lowest elevation, about 1.6 metres, the main drain coming from the left (the north), running under the road carrying water to the south. This drain gets bigger and bigger as it travels to the Belongil Estuary. The cleared paddocks here are impacted by severe ASS.

Further on, looking up to the left, the melaleuca forest planted some seventeen years ago as a trial for effluent reuse was successful, but not followed up. We are now going gradually upwards with Island Quarry, a strange outlier of basalt rock, on the right, and on the left are the sports fields. We are leaving the worst ASS as we climb subtly higher, but on the right, the old Sunnybrand site – the lower portion – is one of the worst polluted areas where several hectares of SEPP 14 Wetland were killed by ASS flows during the 2019 fish kill.

Through the roundabout, we’re now moving onto the sandplain, elevation at about 3.3–3.5 metres. Coffee rock underlies ancient sand. Stormwater drains carry runoff east and southeast to the Belongil Estuary. In the sixties here, bulldozers and loaders carved through the six old dunes and laid the land level. 

We continue, past the A&I Estate on the left, and the West Byron development site on the right. The land then falls quickly again to the Belongil Creek at the road bridge. Crossing the bridge, the land continues rising very slightly again towards Shirley Street, the town drain hidden down to the right in SEPP 14 wetland forest, then onward to town. In summary, the landform is subtle and hard to read, but the water flow paths tell the story.

Both the higher elevation of the West Byron site and the fact that the area is only about 100 hectares means this site is too small to use for the wetland STP as at least 400 hectares are required to achieve a full reuse plan. There would also be practical difficulties in getting effluent to and then on the elevated land, certainly needing pumps. If that sandy site were not to be developed, I would suggest simply stopping slashing it and some strategic planting that would result in a rich ecology within a few years without extra water.

The proposal I’ve put forward, based on extensive work done by all our groups and resource scientists over the last twenty years, suggests a large benefit in restoring the Belongil lowland catchment by neutralising the identified ASS pollution through using treated effluent, which would lead to a healthy productive estuary. It should be done as part of a larger Catchment Management Plan that deals with the stormwater and other problems in a co-ordinated way, a plan long mooted but never achieved.

We now have excellent hydraulic and water quality models, and capable people in Byron to run them, so there’s reasonable certainty it would be done well to return to clean, running, tea-tree water.


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1 COMMENT

  1. I would like to commend Dave Pont for an Order of Australia, knighthood, or whatever is available please. His work in the Belongil has been an extraordinary tale of citizen science meets ecological necessity and when noone else could work out what was happening in the estuary, he did. I watched him kayak and sample, and fly over the catchment in an ultralight to find the answers and he did. Please Byron Council and residents of the Shire, believe in what he is telling you – the only chance of making our very complex local and beloved Belongil ecosystem sustainable is to return the passage of water from the back of the catchment to the estuary mouth to a semi-natural state, which means re-saturating the back of the catchment now occupied by marginal farmland and slowing the water’s passage to “swampy time”. As a life-long lover of the Belongil, the cradle of all Byron Bay ecosystems, I beg you to heed Dave Pont’s prophetic and scientific advice.

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