May to July rainfall in Perth dam catchments has been just over average going by data from the BoM stations: Mundaring, Karnet and Dwellingup. Taking an average of the 3 BoM stations, 561 mm has fallen over the 3500 sq kms of catchments meaning that 1,963 GL of water has fallen free from the skies.
From my graphic showing the drastic decline in catchment yields since the mid 1990′s, we can see that current yields are ~3%.
So let’s say the last 3 months rain has or will put 3% of 1,963 GL into dams, there being a delay in flows entering dams, this equates to 58 GL. Not far off what the current Water Corporation “Water Storage in Our Dams” graphic shows.
Now, it is perfectly clear from my graphic above; that we could easily manage catchments how there were in the mid 1990′s and harvest 6% of rainfall.
This Water Corporation graphic portraying actual flow increases after thinning in the Higgins catchment near Dwellingup, suggests that higher yields are possible in some areas but we will go with the 6% target for now.
So just in 3 short months of average catchment rainfall the Western Australian Government water authority, Water Corporation, has LOST, WASTED, refused to HARVEST ~58 GL of free rainwater.
The proposed new Binningup seawater desalination plant is est to cost ~$1 Billion and will produce 45 GL PA. So quite obviously we have to invest ~$1.25 Billion just to replace this 58 GL of water lost because the Govt is too stupid to manage catchments to a 6% average yield, as they were in the mid 1990′s.
Then there are annual running costs.
Just in the last few days on TV news the following WaterCorp cost data has been quoted for various water sources.
- Dams were 16 cents per kilolitre
- The Kwinana Desal Plant $1.20 per KL
- proposed Binningup Desal $2.00 per KL
So in annual cost terms, using Water Corporation figures, the 58 GL lost will cost ~$116 million to produce in the proposed new Binningup desalination plant.
These investment and annual running costs outlined here put some scale on the cost of kowtowing to ridiculous Green dogmas.