11 May, 2012

Murray Darling Basin "Over-allocation"


In a speech to the Practical Responses to Climate Change Conference on 2nd May the C.E. of the Murray Darling Basin Authority said the following:-
"Leaving aside the challenges of climate science uncertainty for a moment, I would like to turn to what we can be certain about.  There is more than enough information to be confident about the two key challenges in managing the water resources of the Basin:
The first – is over-allocation.  At some point, after the middle of last century, we, the collective governments, began to over allocate the water resource.  The early signals were rising salinity levels during the 1970s, the closing of the Murray Mouth in 1981, the massive blue-green algae blooms in the Darling River in the early 1990s, all well before the significant environmental deterioration we saw in the recent Millennium drought."
Let me deal with each of these claims-
Rising Salinity-it is widely acknowledged that since the introduction of the salt interception schemes salinity has been trending downwards.
Murray Mouth Closing in 1981-The Murray Mouth is a narrow and shallow inlet between sand dunes which naturally closes over.  But the problem has been made worse by the 7.6 kilometres of barrages (sea dykes) which limit natural scouring of the Murray’s mouth by the tide.
Darling River 1990's Blue Green Algae Bloom-We haven’t experienced a  bad algae bloom since 1991. Water quality is improving because of initiatives to reduce the point sources of phosphorous and fertilizers.
Millennium Drought-The allocation process, guided by existing water sharing plans, saw extractions appropriately drop like a stone during the drought.  It is wrong to categorise the natural consequences of drought   as "environmental deterioration".
This excerpt highlights the fact that the Water Act (2007) and the Murray Darling Basin Plan are based on the false assumption that there is unacceptable environmental damage being caused by excessive extractions.

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