Ring tank vs turkey nest dam: how to tell them apart in satellite imagery
When you're going through a licence register trying to work out what's actually sitting in a paddock, the first fork in the road is usually this one: is that a ring tank or a turkey nest? They get lumped together as "off-stream storage" on a lot of applications, but they're built differently, they're licensed differently in most states, and once you know what to look for, they're not hard to tell apart on imagery.
Shape and construction give it away first
A turkey nest dam is almost always circular or close to it. The bank is built up from the surrounding ground level rather than excavated into it, so from directly overhead you get a near-perfect ring, like a doughnut sitting on the paddock. There's no inflow channel because there's nothing flowing in on a gravity line. Water gets pumped or piped in from a bore, a trough line, or a nearby watercourse, and the structure just holds it for stock. Walk the bank and you're walking on fill, not cut.
A ring tank is a different animal. It's built by excavating a basin and pushing the spoil up into a perimeter wall, so the water sits partly below natural ground level and partly behind the bank. That construction method means ring tanks follow field boundaries more than they follow geometry. You'll see rectangular tanks, L-shaped tanks, tanks with a dog-leg where they've been fitted around an existing channel or a fence line. If the shape looks like someone drew it with a property plan in hand rather than a compass, it's almost certainly a ring tank.
What's feeding it tells you the rest
This is the part that matters most for compliance work, because it points straight at the licensing question. Turkey nests are stock and domestic infrastructure. They're fed by low-volume sources, a bore, a small pump off a channel, sometimes just a windmill, and the inlet is usually a single pipe you can spot as a straight dark line running to the ring from the nearest infrastructure. There's rarely a pump shed of any size next to one.
Ring tanks are usually tied to irrigation, which means they're built to move a lot more water a lot faster. Look for a pump site on the bank nearest the river or channel, often with a hardstand or a vehicle track worn into the ground leading to it. The delivery side will show head ditches or pipe risers running out toward cropped country. If you see a turkey-nest-shaped structure with a serious pump site next to it, that's worth a second look, because it might be a ring tank that's ended up roughly circular by coincidence, or a turkey nest repurposed for something a lot bigger than stock water.
Size and siting as a tiebreaker
Turkey nests tend to run small, often under half a hectare of surface area, and they sit wherever it's convenient to run a pipe, which can be well away from any watercourse. Ring tanks are commonly larger, sometimes a lot larger, and they sit close to the river frontage or channel they're drawing from, because every metre of delivery pipe or channel is money the landholder would rather not spend. A big rectangular storage a paddock's width from the river bank is a ring tank nine times out of ten. A small, perfectly round pond out in the middle of grazing country with no river anywhere near it is a turkey nest.
None of this replaces reading the licence file, but it narrows down what you're chasing before you've even opened the register. A structure that reads as a ring tank and isn't on anyone's irrigation entitlement is worth a site visit. A turkey nest with no stock and domestic record attached is a different, smaller conversation.
Matching what's on the ground against what's on the register, paddock by paddock, is the slow part of the job, and it's the part Farm Dam Detection flags for you ahead of time.
See how it maps against your own licence register before the next audit round.