As Australia's power crisis began to ramp up early this month, Snowy Hydro was called on to increase production.
But the hydro-electric generator remains significantly constrained by a surprising problem — too much water.
It's only one example of how weather extremes have deepened the nation's man-made power crisis.
Snowy Hydro's biggest power station is Tumut 3. At maximum output, it can generate 1,800 megawatts of electricity.
That's as much as a large coal-fired power station, but with zero emissions.
The huge volumes of water used by Tumut 3 are either pumped back up the hill to an upper reservoir or emptied into Blowering Dam.
The problem according to Snowy Hydro is that Blowering Dam is full, following back-to-back years of La Niña rain, and increased hydro-electric generation risks flooding, according to an alert released by Snowy Hydro on June 3.
"Generation from Tumut 3 Power Station is significantly constrained by the current storage levels in Blowering Reservoir and the release capacity of the Tumut River.
"In order to meet the predicted energy demands in the coming days, it is possible Blowering Reservoir will fill and spill, potentially exceeding the Tumut River channel capacity.
"In this scenario, there is potential for the inundation of low-level causeways and water breaking out of the river channel onto agricultural land adjacent to the river."
Snowy Hydro doesn't own or operate Blowering Dam. It's managed by WaterNSW, which has been releasing water to lower dam levels there for months, while trying to avoid flooding people downstream.
Over the past 12 months, the La Niña weather pattern has generated about three-and-a-half Sydney Harbours' worth of inflow into Blowering Dam, far more than the total capacity of the reservoir, according to WaterNSW.
Last week, the dam manager warned landholders that in coming days or weeks, flooding may be impossible to prevent.
"With the Bureau of Meteorology (BoM) forecasting a higher likelihood of wet weather ahead, the dam catchment already saturated and the storage also receiving inflow from electricity generation upstream, a future spill cannot be discounted," WaterNSW wrote in a press release.
La Niña rains hit coal miners
Last Thursday, New South Wales Treasurer and Energy Minister Matt Kean was granted emergency powers to direct coal companies to provide fuel for electricity generators.
The need for such drastic intervention was set in train months before, as record La Niña-driven rains caused havoc with coal mines on Australia's east coast.
Pits were flooded and rail lines disrupted.
The Port Kembla Coal Terminal even declared a force majeure due to the rains.
In other words, it could no longer meet its obligations due to an extraordinary event beyond its control.
"It interrupted all the open-cut mines, particularly those in the Hunter Valley", wrote coal producer Yancoal in its quarterly report.
The timing couldn't have been worse for miners. Coal prices were skyrocketing, and miners couldn't meet demand due to the wild weather.
"Coal prices were, let's say, 400 to 500 per cent above prior year levels, but at the same time coal exports fell," said David Leitch, a power industry analyst with ITK consulting.
But La Niña didn't just hit Australia.
La Niña-driven rains also caused havoc for the world's largest exporter of coal, Indonesia.
Indonesia began to have trouble meeting demand, and the price of coal went even higher.
On top of that, a heatwave hit India in April, causing a power crisis there, further driving up coal prices, and that's without even factoring in the war in the Ukraine or demand from China.
In a world where so many things are connected, this affected domestic coal supplies.
"All of those things created an incentive for those coal miners in Australia that had coal for export to effectively hog the rail transport to get coal to the ports," Mr Leitch said.
He estimated domestic coal sales in New South Wales dropped by about a third in recent months, despite record prices.
On Friday, Energy Australia confirmed the coal shortage, writing that "deliveries to Mount Piper are below expected levels in 2022, with strong reliance on our primary supplier, Springvale mine".
With less coal to burn, the demand for expensive gas on the east coast grew by about 15 per cent, according to Mr Leitch.
A polar blast
Fast forward to June, and a stubborn, blocking, high pressure system settled south of the Nullabor, directing freezing winds up Australia's east coast.
When temperatures plummet, power demand goes up, according to the electricity market operator, AEMO.
It's such a reliable effect that AEMO calculates "heating degree days", in other words, how much extra power will be required based on how cold the forecast is.
If it's less than 17 degrees Celsius in New South Wales or Queensland, power consumption rises.
They're a tougher or more insulated bunch in Tasmania — their benchmark is 16C.
On June 7, the entire east coast grid saw its highest demand for electricity in more than a decade, according to electricity analyst and commentator Paul McArdle.
On June 9, Brisbane woke to its coldest morning in six years. That night, Queensland set a new winter record for power consumption.
However Mr Leitch cautions against blaming too much of the crisis on the cold weather.
Less solar in winter
He said cold snaps were starting to catch up with heatwaves in driving power shortages.
"Australian electricity demand is very seasonal," Mr Leitch said.
"It has a peak in about January, and it has another peak in about July in winter, when demand for power for heating residential sources goes up in Victoria and New South Wales and South Australia in particular."
However, the rise and rise of rooftop solar has been increasingly blunting the summer peak, as people power their air conditioners during the day from their solar panels.
"But in wintertime, there's a lot less solar. And so the demand comes back on the thermal power suppliers, the coal and the gas. And when we have the plant breakdowns, that's what causes the issue," said Mr Leitch.
Average solar generation in recent weeks has been about half that generated in summer, according to the OpenNEM platform for National Electricity Market Data.
"For some years, I've been predicting that previous power crises occurred in summer, when heat would cause the coal generators to break and transmission lines would sag and demand would be very high in a heatwave," Mr Leitch said.
"But as we get more and more solar, the summer problems get less. But the winter problems increase because you get a lot less wind and solar."
As temperatures plummeted, the wind blew
As the market began to melt down in the face of tight supply and demand, wind power offered one bright spot.
On June 14, both South Australia and Victoria set new records for wind power generation.
"It's not very common for wind generation to exceed 5 Gigawatts but in the last seven days, and indeed last three weeks, we've seen wind generation exceed that level quite a bit," said David Osmond, principal engineer at wind power company Windlab.
He said since the beginning of June, wind power totals had been more than 40 per cent above average.
