It’s hoped that a new approach to flood plain management will help stop fish kill events like this one in 2008 one which killed 300 tonnes of fish.
It’s hoped that a new approach to flood plain management will help stop fish kill events like this one in 2008 one which killed 300 tonnes of fish. Philip Herold

Bid to curb fish kills in Richmond

A NEW flood model covering the entire Richmond Valley flood plain will be presented to the Richmond River County Council on Wednesday.

With an accuracy of plus or minus 26cm across the whole study area, and a confidence factor of 95 per cent, flood plain facilitator with the council, Michael Wood, said the tool would be used to provide information for ecological modelling, planning, and quantifying the extent of black water sources – back swamps that create water which is poor in dissolved oxygen during summer floods.

The digital elevation model took five years to create and follows on from the release of extensive studies carried out by Southern Cross University’s Dr Vanessa Wong which pointed to back swamps on the flood plain as delivering essentially toxic water to the river in the days following a hot, summer flood.

Of course drains are the culprit which deliver much of this black water to the main river channel, and which then can lead to massive fish kills.

Mr Wood said that acid water was not the main issue in summer flood fish kill events.

The public debate about how best to manage black water and fish kills has become more vocal just lately, with comments from Lismore-based wetlands scientist David Pont, part of the Water And Carbon Group, who said he was seeking to make carbon-sink ‘farming’ a reality.

Analysis of the benefits of a potential scheme involving 10,000ha were detailed by the Water and Carbon Group, setting aside 1000ha as lagoons and 3000ha to be left to growing rushes and reeds. Neither of these areas would qualify for carbon credit funds under a Kyoto scheme.

But Mr Pont said the remaining 6000ha planted with casuarinas and paper bark trees had the potential to return $100m over a 30-year period for an initial outlay of $25m. “That is a four-fold return,” he said.

While Mr Wood said there was no real ‘panacea’ for fixing the problem of fish kills, he noted that there was plenty of scope for turning ‘rubbish swamps’, as they were called in the good old days, into managed landscapes where profit could be made at the same time as helping reduce black water run-off.

 

 

 

 

SMS 0428 264 948 or email opinions@northernstar.com.au



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