LAUNCESTON has little hope of earnestly solving its silt problem without releasing the South Esk River, Launceston Flood Authority chairman Alan Birchmore believes.
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"Almost every problem that we've got in the upper reaches is to do with waterflow,” Mr Birchmore said.
Hydro Tasmania installed a dam on the South Esk in 1955 to service the Trevallyn Power Station
The flood authority managed to convince Hydro to release 25 cumecs of water from the dam over three days in 2013 after silt raking programs to flush out the Tamar’s yacht basin.
This was at a time when the upper Tamar was in its worst condition, choked by mud and sludge.
Surveys commissioned by the authority after the trial revealed a huge drop in sedimentation of the first release of water and more on the following two releases, taking almost 142,000 cubic metres of sedimentation out of the basin in four months.
In the last year, more than 100,000 cubic metres has steadily built up in the basin.
"And that's scary," Mr Birchmore said.
"The Trevallyn Power Station generates less than 3 per cent of the state's power – that 3 per cent of power is powering all the businesses in Launceston but we've got a sewer running through the city.
"The sewage gets the blame but when those plants were designed, they were designed for 65 or 70 cumecs coming down the South Esk all the time – at least 30 times the current water flow.
"There would be a big benefit to Launceston, not only for raking but from diluting and washing away what is coming from those plants."
Mr Birchmore said in consultation with an energy expert, three-quarters of the Trevallyn’s power generation could be taken on by a new plant after the dam at a cost of $20 million – to be run by a potential private operator at a $8 million annual profit.
He said a flowing South Esk would negate the Tamar’s unique tidal flow which had an incoming tide that is 24 minutes shorter than the outgoing tide.
These movements push silt up the river rather than down the river.
NRM North assess the Tamar’s health each year, released in the form of a report card.
The zone from Launceston to Legana received a D rating last year, indicating poor ecosystem health and an ability to only reach water quality targets half of the time.
"If we hadn't lost the South Esk, Launceston would have this rating," Mr Birchmore said.
Bass Liberal MHR Andrew Nikolic and Bass Labor federal candidate Ross Hart have both expressed support reinstatement of South Esk River flows.
