In praise of sewage

“Cockle Creek? Ooo, I wouldn’t put in there” my sister’s mate, the local, said “They’ve been dumping heavy metals in that spot for years! And there’s the sewage farm up the river as well.  I’d steer well clear”.

I muttered to my sister as we walked away “What do you think? Are you worried about heavy metals and sewage?”

“Nah!  Let’s do it!”

Sunrise on Lake Macquarie

Sunrise on Lake Macquarie

The power of poo.  Over the last couple of years, I’ve been hearing a lot about it from my fabulous friend and colleague, Cath Simpson, at this very minute writing a documentary for Radio National full of plops and splashes.

Thanks to some bad experiences with cholera and typhoid, we modern city dwellers generally a bit iffy about human excrement. But the bacteria that dwell in and on us – our own personal ecosystems – seem to be quite critical to human health.   While I’m a huge fan of the toilet, poo is not all bad.  If you have a nasty case of Clostridium difficile, for instance – an infection that kills 30,000 Americans every year, often older people in hospitals who have had their bacterial ecosystems depopulated by antibiotics – a “faecal transplant” from a healthy donor is might well be your best chance of a cure.

If the much of Western world, with its convenient superphosphate fertiliser and cow-pat free central heating, has been a bit “ew” about excrement, one sub-culture has held the faith.  Bird watchers have never lost confidence in the value of ordure.

Cormorant diving crop for trim

Painterly pied cormorant fishing in Lake Macquarie

When Birdlife Australia asks “where’s your favourite birdwatching spot?”, do you choose an offshore island, fringed with white sand?  the lush splendour of the tropical rainforest?  Or choice number three, a sewage treatment plant? And you guessed it, the first comment is a ringing endorsement of the glories of the Alice Springs Sewage Ponds.

So I wasn’t really surprised at the new and exciting birdlife I saw up  Cockle Creek in amongst the drowned computer monitors, abandoned bridge footings and Impressionist riverscapes subtly enhanced by a discreet discarded tyre.

So many striated herons I got bored of taking photos.  White-cheeked honeyeaters.  Orioles.  Black faced cuckoo shrikes. White breasted woodswallows, showing off their 80s batwing styling.   Double-banded finches with their neat dress shirts, black ties and cummerbunds.

Why are sewage treatment plants so great for birds?  Well, wetlands are a particularly threatened habitat – a third of Victoria’s wetlands have been drained over the last two hundred years, for instance – and old-style sewage ponds offer alternative places for birds to feed and rest, especially during droughts.  With plenty of nutrients, the settling ponds of sewage treatment plants actually offer more invertebrate snacks than natural wetlands, and sustain a greater range birds. Christopher Murray’s research in Victoria has found that newer treatment plants – the dynamic sounding “activated sludge” facilities – that take up less expensive real estate than old-fashioned waste stabilisation ponds (and smell better) are less appealing from a waterbird’s point of view.

If the news on sewage plants is pretty good, I’m not so sure about the heavy metals. Cockle Creek really has been a dumping ground for cadmium and lead, among other things, from the smelter in Boolaroo, on and off for more than a century.  There’s black slag from the plant tucked away in all sorts of unexpected places around the lake shore and lead, zinc, mercury and cadmium lurk in the creek’s sediment, 70 centimetres deep.

The smelter closed down in the noughties and the site is still being “remediated” for housing.  Previous “abatement” strategies seemed to involve scraping off a few centimetres of topsoil and (after most of the local pre-schoolers were found to have worryingly high levels of lead in their blood) urging kids to  “Wash wipe and scrape – you’ll be right mate!”. In the 1980s and early 1990s, the streets closest to the “The Sulphide” were rented out on the strict condition that the household should have no children or pets.

There’s a giant Bunnings there already, though, amidst the rubble.  Perhaps the logic is that the visiting DIYers are heading home to put a mallet through an asbestos wall, so where’s the harm in throwing in a spot of bonus lead?

The local birds seem to be doing okay, though.  A pair of ospreys nest at the top of a Norfolk pine at Speers Point, where Cockle Creek flows into Lake Macquarie, and this last year they’ve had chicks.  Osprey are locavores and since they’re at the top of the food chain, anything toxic in the fish they eat ends up in their chicks.  Eventually.  It takes a while for our endlessly updated array of contaminants – from DDT to teflon, fire retardants and hypertension medications – to make it into the bloodstream of the baby raptors.

Osprey wings bent crop wide

Osprey with fish at Speers Point, Lake Macquarie

I’ll be back to Cockle Creek for sure, to see what the local sewage has in store for me.  Trying to tread lightly, and hoping not to feel too much lead and mercury squelching between my toes…

D in canoe at dawn small more waterReferences

Murray, C. G. & Hamilton, A. J. (2010). Perspectives on wastewater treatment wetlands and waterbird conservation. Journal of Applied Ecology, 47(5), 976–985. DOI: 10.1111/j.1365-2664.2010.01853.x

Murray, C. G., Loyn, R. H., Kasel, S., Hepworth, G., Stamation, K. & Hamilton, A. J. (2012). What can a database compiled over 22 years tell us about the use of different types of wetlands by waterfowl in south-eastern Australian summers? Emu: Austral Ornithology, 112(3), 209–217. DOI: 10.1071/MU11070

Murray, C. G., Kasel, S., Szantyr, E., Barratt, R. & Hamilton, A. J. (2013). Waterbird use of different treatment stages in waste-stabilisation pond systems. Emu: Austral Ornithology. DOI: 10.1071/MU12121

Murray, C. G. & Hamilton, A. J. (2012). Sewage ponds a refuge for wetland-deprived birds. ECOS, 175. http://www.ecosmagazine.com/?paper=EC12418

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One thought on “In praise of sewage

  1. Beautiful shots, especially of the raptors! I’m very envious of your flying bird pics and I share your praise of poo. A shame about the heavy metals and other contaminants though. Funny how they would rent the houses to people without kids and pets. I had to laugh at your comment about DIY people, asbestos and lead. Sadly, it’s probably close to the truth.
    It is interesting how we view poo in the western world. On a personal note, when my kids played in dirt and had plenty of exposure to manure on farms, they were healthy and strong. It’s only when they moved to live in the poo-less, low-dirt, chlorinated water, city environment that they started having regular health problems – ear, nose throat and intestinal. Of course there are other factors involved such as more contact with sick people, less home grown food and increased air pollution, but I do wonder if the reduction in dirt/poo bacteria contributed. Loved the post!

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