The Dishonesty of John Ringham (CEO of SA Water)
In his submission to the Parliamentary Inquiry, John Ringham, Chief Executive of SA Water, refuted claims that “the lower water levels in Polda Basin have been caused by SA Water over-pumping from the basin.” (Sub 34). He stated: “Good 2010 Spring and early Winter rains as well as continued solid rain throughout 2011 has resulted in a general recovery in water levels of over 1 metre across much of the Basin.”
A detailed examination of the water level readings for Winter/Spring 2010 through 2011 (taken to be from June 2010 to December 2011) of the bores covering the Basin tells a vastly different story. The individual bore readings are found in the Appendix 1. If the recovery of all the bores is averaged for the period, then the result is not 1 metre but 40cms.
NOT ONE BORE had a rise of over 1 metre during the period stated by the CEO of SA Water.
This is an indication of the extent to which the Chief Executive is prepared to obscure the truth.
However there is a better way of assessing just how much the rain between June 2010 to the end of December 2011 can be measured. This is by comparing the actual change in water level over that time, with the greatest variation in water level that has occurred in the bore since it was started. The difference (diff.) between the highest recorded water level (High) and the lowest recorded water level (Low) is recorded and compared with the amount of the recovery (Recovery) over the period selected by Ringham.
The percentage of the difference (%age of diff.) is the amount of recovery compared to the overall difference (diff.) between the historic high and low water levels.
This comparison provides the opportunity to assess the recharge that occurred with the amount of recharge necessary to replenish the bores and hence the whole basin. (See the diagram at the top of Appendix 2).
If the recharge for June 2010 to end of December 2011 is 90% or more of the bore water levels, then it can be concluded that the bores have not been depleted too extensively. However, if the recharge for the time is significantly low e.g. below 20% then the basin must have been significantly depleted if this recharge is not enough to restore it close to its historic maximum.
Appendix 2 shows the measurements that are needed, and the results of the comparisons. On average, the recharge is approximately 15% of the total necessary to fill the bore (basin).
While some percentages are of the order of 25-28% (a significant recovery) approximately a third of the bores have a recovery of less than 10%!
Appendix 2: The Recovery compared with the Variation in water levels of the Bores
Bore No. High(m) Low(m) Diff.(m) Recovery(cm) %age of diff.
SQR002 37.8 33.8 4.0 62 62/400 = 15%
SQR003 37.8 4.1 33.6 61 61/410 = 14.8%
SQR008 37 34.4 2.6 55 55/260 = 21.2%
SQR009 37.3 34 3.3 60 60/330 = 18.2%
SQR010 37.4 34 3.4 56 56/340 = 16.5%
SQR021 42.8 40.5 2.3 29 29/230 = 12. 4%
SQR028 38.4 35.1 3.3 59 59/330 = 17.8%
SQR030 36.9 33.3 3.6 63 63/360 = 17.5%
SQR031 37.0 34.7 2.3 42 42/230 = 18.3%
SQR037 48.3 46.3 2.0 14 14/200 = 7%
SQR073 39.4 36.0 3.4 45 45/340 = 13%
SQR075 39.5 36.8 2.7 17 17/270 = 6. 8%
SQR077 41 38.5 2.5 24 24/250 = 9.6%
SQR079 45.2 40.75 4.45 30 30/445 = 6.7%
SQR085 42.0 38.1 3.9 25 25/390 = 6. 1%
SQR086 44.9 41.1 3.9 31 31/390 = 7.1%
SQR088 40.5 37.7 2.8 19 19/280 = 6.1%
SQR095 37.3 34.6 2.7 68 68/270 = 25.1%
SQR097 36 33.8 2.2 61 61/220 = 27.1%
SQR100 38.5 35.6 2.9 54 54/290 = 17.9%
SQR101 49.1 47.2 1.9 1 1/190 = 0.5%
SQR105 42.7 41.1 1.6 45 45/160 = 28.1%
SQR106 37.8 35.3 2.5 57 57/250 = 23%
SQR110 36.8 33.7 3.1 62 62/310 = 20.0%
SQR111 39.7 37.5 2.2 55 55/220 = 25.0%
SQR113 36.6 34.3 2.3 59 59/230 = 25. 1%
SQR114 39.4 36.8 2.6 52 52/260 = 20%
SQR117 39.5 34.6 4.9 39 39/490 = 7.9%
SQR118 37.1 34.3 2.8 39 39/280 = 16.1%
TIN079 35.8 32.4 3.4 24 24/340 = 7.1%
On average then, based on the limited information available, it would take nearly 7 times the rain that fell in the period June 2010 to December 2011, to bring the basin back to approximately full.
This is a clear indication that the basin has been over-extracted – if the basin was being managed in an ecologically sustainable manner, the recovery should have been sufficient to replenish the basins by 80% or even more.
Given the variability in rainfall, it will be many years before the basin is close to full recovery, and this can only happen if there is no further extraction for the public water supply. How complete the recovery should be (100%, 95%, 90%) should be a decision for the community and NOT SA Water.
No matter what the level of the basin, any ongoing extraction must be a small fraction of any effective recharge, and nothing like the amount being taken in recent years.
Location of the bores on Polda Basin.
Location of the bores plus the water recovery during the Ringham time period.
