We are the Estuary
This is how I explained estuaries to my nine-year-old son: an estuary is where the river meets the sea. Where fresh water merges with salt to become what is called brackish water. In-between water. I tell him that estuaries are where human connection to the water is at its most concentrated. Our cities are built on them, so estuaries are also places where we meet the sea. Together we run through all the ways people come into the picture: drain meets sea, house meets sea, road meets sea, and so on. People tend to complicate things.
Our home on the man-made island of Carrington is ringed by an estuary with two sources. To the east it’s where the Hunter River ends its 300 kilometre journey and spills out into Newcastle Harbour, the world’s largest coal port. To the west it’s where the Throsby Creek winds its way around, carrying the wastewater from 3,000 suburban hectares. The Throsby is a fraction of the size and significance of the Hunter, but it frequently occupies my thoughts. I visit at least once a day, usually on morning walks with my wife. I love that it’s never quite the same, never fixed. Tidal estuaries change constantly throughout the day, moving between states and sizes. They move between time too, and the sediment of our history keeps getting deposited into our future.
Carrington was once a low-lying floodplain that the Aboriginal people called Onebygamba. Mud-crab place. Rich in marine life and vegetated with melaleuca and mangroves, Onebygamba would get completely submerged with the tides. The Throsby itself was once a natural free-flowing river banked with alluvial soils. Alluvial comes from the Latin alluvia which means to wash. Alluvium is what we call the rich, fertile silt and clay deposited by a fluvial process. Fluvial is the word used to describe the action of the river. Fluvial. Alluvial. Fluid. Alive. The estuary is a miraculous self-restoring ecosystem that was seen by colonists as a land to be corrected. So began a project to raise the island up above sea level, at first with decades of ship ballast then finally with soil dredged from the harbour. Factories and silos and sheds quickly rose up on the new high ground, as did little miner’s cottages like our own.
Settler activity expanded along the banks of the Throsby into what are now dense inland suburbs like Tighes Hill and Mayfield. Slaughterhouses and breweries took up residence on the shores creating new tributaries of waste that would flow directly into the creek. By the turn of the century locals described the creek as a “degraded, evil smelling drain”. Despite this, for a time, stingrays would still make their way up the water from the sea towards homes. Bull sharks too, sometimes feasting on dogs and horses as children would play in their home-made boats nearby. With each passing year urbanisation would continue to reform the natural floodplain. When the Depression hit, local men were put to work on building the stormwater network that feeds the Throsby today, entombing the flow in concrete channels underground. We didn’t drain the swamp; we buried it.
537km worth of pipes travel through the Throsby catchment. Living waterways have been straightened out and redirected into plastic pipes. The whole thing functions through gravity feeding whereby the water simply runs down from the highest points of the catchment and into the estuary. Gross Pollutant Traps and Continuous Deflective Separators are placed throughout to capture large pieces of litter, debris, and soil however these don’t stop the incalculable volumes of micro and nanoparticles coming through, nor the liquid pollution that reconstitutes the water. When you look at the creek, here’s what you’re not seeing: bacteria and pathogens from sewer overflow; nutrients like nitrogen and phosphorus from fertilisers and pesticides and animal waste; decomposing plants and animals that frequently choke out the oxygen; eroding metals like lead, copper, zinc, mercury, and silver; hydrocarbons from oil and petrol leaks; and an assortment of forever chemicals from cleaning products and plastics. These are aqueducts of abandonment. This estuary is freshwater, saltwater, and the entire periodic table.
There is life to be found throughout the creek, but it is drain life, not river life. This is the domain of crows and bats, rats and periwinkles, and thistles and algae. The impoverished and the intractable. A mix of the hardiest and most opportunistic survivors. White ibis live here in huge numbers, but only because we destroyed their homelands first through drought and deforestation. We call them bin chickens, but they only thrive on our waste because there is so much of it available. I’ve tried to map out the life of the catchment zone, looking for exposed sections of drain to see what’s there. I am surprised to see shells of Sydney rock oysters creating filled collars around rusted pipes some eight city blocks from the ocean. This creature reproduces by broadcast spawning, which means that males release sperm and females eggs directly into the water. The resulting larvae latch themselves to hard surfaces to grow into adult oysters. So sensitive to the temperature and chemical conditions of the estuary water, oysters have their own terminology for flavour profile, merroir, similar to the way grapes respond to their terroir. I wonder what the merroir of these oysters is like as I watch vape pens and witches hats and dead mynah birds float by.
This is flood country. This is the domain of East Coast Lows, so powerful that they can drag a 76,000-tonne cargo ship into shore. I often look at archival photos from some of the great deluges and the images are striking and surreal. Pubs and homes look like they’re floating in space, with sky and land erased by the same white emptiness. But it’s not the water that looks out of place, it’s us. We keep trying to build up over it, push it out of our way, deny it. But it keeps coming. The latest climate modelling suggests that by the end of the century, rising sea levels could see Carrington submerged underwater once again. The most extreme predictions say that we’ll experience a 3-metre rise by 2100. Our home insurance bill has already increased based on these predictions. The council has spent a good amount of time and money building up our seawalls. What began as conquest is starting to feel like bracing, holding on to what’s there rather than pushing forward to what could be.
Lately I’ve been noticing subtler but more frequent signs of change. King tides have become more common and more severe, and this seems to have had a lifting effect in the daily tides. The water is often coming right up to the path, covering the little beaches and then receding out fully to reveal the creek’s belly. Lobster traps and shopping carts and abandoned bikes poke out from the mud and from a distance they look like the bones of ancient sea creatures and if the wind is going in the right direction, it smells like ancient carcass too. As it ebbs and flows, ebbs and flows, the water seems to want to reveal to us the mess we’ve made before covering it all over again. Here’s what you’ve done, here’s what’s coming.
Year after year the water will rise. New homes will become harder to build and existing homes will become harder to insure. We will enter an era of retreat, an age of rezoning. Our house is near the centre of the island so we’ll be able to stick it out for a while but we’ll start to say goodbye to neighbours on nearby streets as the government buys back property and people begin to relocate. The Throsby will widen. The estuary will grow. Once the kids are all out of home with families of their own, the West Antarctic Ice Sheet will enter irreversible collapse and the final, unstoppable stages of inundation will begin. Dense seawater will push its way up the creek, overwhelm the network, reclaim the land, and salt everything in its path. The mangroves will return, not as a sign of restoration, but a redrawing of the map.
When my son is older I will explain to him that we are the estuary.
We are the in-between place.