Cloud Seeding Conducted in Tasmania amidst Flood Warnings

Cradle Mountain in Tasmania

On June 5th this year, the town of Ouse in Tasmania suffered severe floods that claimed the life of eighty one year old farmer Trevor Foster. A further two people remain missing.

A matter of hours before Ouse was deluged, Hydro Tasmania – a government owned electricity generator that operates multiple dams in the country – engaged in a cloud seeding program in an effort to instigate rainfall. An official statement on Hydro Tasmania’s website following the flood gives their reasons for this:

A cloud seeding flight was undertaken on Sunday morning, 5 June. It was targeting the Upper Derwent catchment, specifically Lake Echo, one of the storages that remained below its desired level. There were no flood warnings in effect for the Upper Derwent at the time of the flight.

This area received a substantial, but not excessive, amount of rain after Sunday morning’s flight.

Water in the Ouse River came from the overtopping of Lake Augusta due to the flood event. Lake Augusta is not in the catchment targeted by Sunday’s cloud seeding flight.

Hydro Tasmania’s cloud seeding program is currently on hold.

Hydro Tasmania’s response to the flood has been met with criticism by residents and figures from Government. The Weekly Times, an Australian print and online resource, reported on June 14th the level of fury amongst Tasmanian farmers.

Tasmanian Farmers and Graziers Association president Wayne Johnston said there was “white-hot anger” among producers near the Upper Derwent and Mersey-Forth catchments.

“A lot (of farmers) thought it was an act of nature, but to find out perhaps a government agency could have contributed to loss of infrastructure and livestock, they were livid and most of all disappointed,” Mr Johnson said.

This same article by The Weekly times also reported how Tasmania has been facing a growing energy crisis after dam levels in the country dropped to 16% in February. As a consequence of a receding water supply, Hydro Tasmania brought forward a planned cloud seeding program which began in April 2016, a month earlier than usual.

ABC in Australia reported back in March 2016 that storage levels at two of the state’s biggest catchments were likely to fall to less than 12% capacity:

Hydro Tasmania’s dam levels are at record lows at 15.5 per cent as the Basslink power cable remains out of action preventing it importing energy from the national grid.

Rainfall in the North West slowed the drain to 0.6 per cent in the past week but Lake Gordon, in the south west, and the Great Lake in the central highlands have not fared so well.

Lake Gordon’s storage is down to 8.3 per cent and Hydro Tasmania chief executive Steve Davy said he was not sure how much further they could draw down on the lake.

“Gordon Power Station can operate down to quite low levels but it would be operating at much much lower capacity as the levels reduce,” he said.

While Hydro Tasmania has tried to forecast different scenarios, Mr Davy said it had not operated at levels this low before.

“We’ll respond to what really happens and when we hit operating difficulties well start moderating our use then,” he said.

Hydro Tasmania is also using Great Lake sparingly as it is down to 11.4 per cent.

Two months later, ABC reported an upsurge in dam levels, a month after cloud seeding programs began:

Tasmania’s energy crisis has “turned the corner” as dam storages climb to 20 per cent, an increase of almost 4 per cent in seven days, Energy Minister Matthew Grooms says.

Mr Groom said the rains had provided a much-needed boost for the state.

“The strong inflows means that Hydro Tasmania has been able to begin the process of rebuilding storages from 12.8 per cent at the end of last month, to 20 per cent today,” he said.

“While there is no doubt we have turned the corner on this issue over recent weeks, there continues to be a lot of work to do in managing ongoing challenges.”

Earlier this month, The Mercury published an article querying the timing of the cloud seeding. Of note were comments by acting energy minister Peter Gutwein, who confirmed that the Government had received a preliminary report from Hydro Tasmania. But he did not provide any detail on what the report contained:

“The preliminary report notes that cloud seeding is a complex science and further analysis is required,” Mr Gutwein said.

“Hydro Tasmania and the Government understand the concerns of the community, which is why it is important we take the time needed to have this matter properly considered. We expect a final report from Hydro in the coming weeks.”

The wait for a final report to be received and made public continues as of writing. So the question remains about how much knowledge Hydro Tasmania had about the impending flood.

Farmer Scott Ashton-Jones gave his view to ABC shortly after the event:

“The extent to which cloud seeding has exaggerated the flood is still to be determined of course, but the evidence from previous cloud-seeding operations is that it works and therefore it will have exaggerated the flood to some extent,” he said.

“Hydro has always claimed positive results from cloud seeding.”

George Mills, a fellow farmer, told ABC in the same article that he had heard the cloud seeding flight on the Sunday morning – the day of the flood – and wondered what was happening:

“We want to understand whether the cloud seeding has helped to create this massive flood from the local rivers which we’ve never ever seen,” he said.

“If the Hydro have had something to do with that with their cloud seeding, well we want to understand that because in the future we need to have closer information.”

It seems the key to understanding the connection between the cloud seeding and the flood lies in weather warnings issued for regions of Tasmania when the cloud seeding took place.

The Bureau of Meteorology said this after the flood, again reported by ABC:

“The first media release alerting the Tasmanian community to likely impacts of the event was issued on Friday 3 June,” a weather bureau spokesperson said.

“Detailed updates have been provided directly to the local media throughout the event.”

The spokesperson said the first flood watch for Tasmania was issued at midday on Friday, with warnings following on Saturday.

“The first flood warnings were issued on Saturday afternoon: six to 12 hours before significant rain began to fall across northern Tasmania,” they said.

The same article concludes with:

The first minor flood warning for the Ouse and Derwent rivers was issued at 10:36pm on Sunday, after the cloud seeding flight took place.

The next day, unprecedented rainfall resulted in major flood warnings for seven Tasmanian rivers, including the Derwent and Ouse.

With all this information brought together, Hydro Tasmania clearly have a case to answer in their involvement in the flood and the resultant loss of life.

The release of a final report into the incident is expected by Hydro Tasmania soon. This blog will report any further news on the story as it occurs.

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