AN OBSERVATION OF THE CONFLUENCE OF STATISTICAL ABERRATIONS, DAM RATIOS, TIMING AND UNCOMMON RAINFALL EVENTS THAT COMBINED TO PRESENT OUR DAMS AS VICTIMS OF A SEVERE DROUGHT. THIS IS NOT THE CASE. THEIR INFLUENCE ON CONCLUSIONS REACHED AND ACTIONS TAKEN.

Author : J. V. Hodgkinson F. C. A. Chartered Accountant : August 2006 to December 2009

The Underlying cause of our depleted dams had the appearance of "drought". However most people would not class 80 percent of rainfall compared with the Bureau of Meteorology long term average 1961 to 1990 as a "drought". This is the case in the catchments. Even less people would class it as a "drought" when closer examination of the rainfall shows that the inflow producing four Summer months had been quite normal with 99.7% in the Wivenhoe and 91.3% in the Somerset catchments. The 20% deficiency was in the low inflow producing eight non-summer months.

This incorrect conclusion of "drought" has clouded the real underlying cause of our depleted dams. It is the random nature of large scale rain depressions and they are our main water supply. They occur on average every 4 years and have the capacity to fill our dams in a few days. The last gap was six years 2001 to 2007 and caused a major and expensive panic. Further evidence is available in the tab DEPLETED DAMS or Click here

Dealing with those large scale events that extend beyond the 4 year average requires a very different approach than dealing with a "drought". The current water resource strategy has ignored the short history of the Wivenhoe dam.

For those coming to this page from "Climate Change" a click on this tab will get one to the backup material.

Reprint from Gympie Times 24.12.2009. Reprinted with permission and without comment.

We pick up the tab for dam lies

Gympie Regional Council engineering director Bob Fredman with stacks of government submissions and council responses over the Traveston Crossing dam.

Craig Warhurst

August 2009

Ministers Hinchcliffe and Robertson have clarified their position which is outlined in the index page.

They no longer mention these reports and the conclusion is that they are no longer relevant.

The following is a summary:

* Neither the Engineering or Hydrology reports deal with the transfer of water via two-way pipeline from Wivenhoe/Somerset to Borumba dams.
* Both reports dealt extensively with Weirs in the Mary Valley. That aspect had been withdrawn by Mr McMah in his alternative EIS lodged in November 2007. It was followed by a letter to the Coordinator General in August 2008 when it was realised that they were being included in public statements.
* That left the Borumba dam. The Engineering report provided a costing of a three stage wall for a height of 1,650,000ML capacity dam and nothing related to the two-way pipeline.
   The Hydrology report carried an addendum which stated :
 The Borumba  catchment is relatively small ( approximately 465 km2 ) for a Dam required under stage 3 McMah proposal (between 1,500GL and 2,000GL) as such likely to fill and spill due to the influence of large scale meteorological influences which will almost always influence the Brisbane River catchment at the same time. As such Borumba is likely to be overflowing generally during those times in which Wivenhoe & Somerset are also close to Full Supply level.  

To me, this is an astonishing statement. The Borumba is unlikely to fill from its own resources except in the event of an 1890 flood followed by an 1893 flood of 22 days. If it were correct, nether the Traveston or the the McMah plan would be needed with the exception of the two-way pipeline. 

Additional use of, or the better use of, water from the Wivenhoe/Somerset 

The advice offered to the Engineers and Hydrologists was in relation to the "Water Resource (Moreton) Plan" either in draft or final form. The associated Act to monitor and enforce had not been enacted at November 2009.

Currently there is 80,000ML held in reserve in that system. The Yield is 360,000ML and the allocation is 280,000ML. This reserve can be held in the expanded Borumba thus releasing the 80,000ML for allocation. Together with the additional 52,000ML from the expanded Borumba we have 132,000ML which is comparable in itself to the initially propose Traveston for all three stages of 150,000ML.

It is now certain that flood water is detrimental to Moreton Bay. The last flooding rains produced that undeniable result. All of the Wivenhoe/Somerset was retained thus reducing what was an even greater ecology disaster for the Bay.

The Wivenhoe/Somerset system is inadequate to hold large scale events. While the Moreton WRP does not actually calculate the Mean Annual Flow, it sets out the manner of calculation. One can arrive at the calculation in another way.

If the yield is 360,000ML and that represents 34 percent of the flow then what is 100 percent? = 1,058,823ML and it is required each year. This is close to a volume of water the equivalent of the Wivenhoe dam's total capacity of 1,165,000ML.

Doubling of the storage capacity by linking the Borumba Dam expanded to 2,000,000ML will go part of the way to mitigating this problem.

This possibility was not canvassed in the construction of the Moreton WRP.

The Raising of the Wivenhoe Dam wall was considered by Engineers GHD. They determined that an additional 80,000ML could be obtained if this was done. It had complications for existing infrastructure.

However it is available subject to an Environmental Impact Study (EIS). This EIS will expose to public scrutiny our proposal and the construction base of the Moreton WRP on which the Government determined that 66% of all water from that system must reach the River mouth.

End of summary

Initial website resumes

Reports or "assessments"

There were three reports. 

Hydrology

This website report was dated 17th September 2007.

The introduction to the report reads “The alternative proposed by Mr McMah included consideration of extraction from Wivenhoe/Somerset storages in the Brisbane Valley to further supplement supply to Borumba. The inter-basin transfer component has not been included in the hydrological assessments undertaken in this study due to advice that there are extreme limits on available water for transfer out of the Wivenhoe/Somerset under the Moreton Plan Area.”  The underlines are mine for emphasis

In my view, the advice was inaccurate on two counts.

1. The water involved is flood water that currently goes over the Wivenhoe dam wall. It is extracted and stored in the Borumba for later return to the Wivenhoe/Somerset in times when “uncommon events” are not active.

2. The Borumba surplus may be also transferred in part or whole to the Wivenhoe/Somerset depending on the overall water management.

The Water Resource (Moreton) Plan 2007 specifically provides for our proposal. Not only does it provide for it but the Plan is designed for change should this position arise. The section of the Water Resource (Moreton) Plan 2007 follows the Engineering report for readability.

Ministers Robertson and Hinchcliffe have advised that they have determined that 66% of the mean annual flow is to go to the Brisbane River mouth. That aspect is extensively discussed in this website.

Engineering report

The Engineering report referred to the Hydrology report and also excluded the inter-basin transfers from and to the two dams. The main purpose of the exercise was lost.

In an earlier time Ron McMah had asked for an investigation of the Weirs in the Mary Valley . He later withdrew that request in writing and it was never part of our joint submissions under the EIS for the Traveston Dam.

The Engineering report dealt with the Dam wall in three stages and the significant cost of the Weirs. This had the effect of almost doubling the cost and was used to distort the cost of our proposal.

Result

The Wivenhoe/Somerset surplus was excluded. This left the Borumba Dam to compete by itself with the Traveston which was never a proposition. In addition it was left to bear an extraordinary amount of cost involved with the Weirs in the Mary Valley . Government sources have consistently applied these reports to our proposal when requested by outside sources to explain their objection to our proposal.

Water Resource (Moreton) Plan 2007   No31, 2007  

An extract from our letter to Minister Hinchcliffe dated 31st January 2009

An overview of the mechanics of our proposal to observe conformity with the Act

It was necessary to deal with the mechanics of the proposal in order to see that

 The Act provides

Part 3

Section 11  General outcomes      (page 9)

                   (1) Each of the following is a general outcome for surface water in the plan              

                        area-

(a) to provide for additional water to be taken from the plan area for future water entitlements;

PART 10              (pages 57/58)

Section 97  Amending or replacing plan

            The Minister must consider amending this plan or preparing a new plan to replace this plan if the Minister is satisfied-

            (a) in relation to the outcomes mentioned in part 3-

(i) water entitlements in the plan area are not sufficient to meet water needs sourced from the plan area having regard to-

(A) the extent to which water is being taken under water entitlements; and

(B) the efficiency of present, and expected future, water use; and

(C) emerging requirements for additional water; and

(D) alternative water sources including, for example, recycled water and water savings from improved efficiency of water use; and

(E) the likely time frame in which additional water will be required; and

(ii) there are economically viable and ecologically sustainable uses for additional water; or

(b) the plan is inconsistent with the SEQ regional plan.

It appears clear that our proposal fits within the Legislation particularly Part 3 (1) and Part 10 (C) and (D) in particular.

It requires the Minister to observe our proposal and make a decision.

Any inconsistence, if any exists, with the SEQ Regional Plan would come under the Minister’s jurisdiction. The Act, as it is drafted, has anticipated a changing situation.

Perhaps the Water Resource (Moreton) Plan 2007 legislation should be amended and extended (and renamed if necessary) to include an enlarged Borumba Dam, to facilitate the completion of a true ring-road style grid to better service SE Queensland.

If there is argument with our reasoning, then we say this:

The dynamics of SEQ including the Moreton Plan (2007) have changed with the introduction of the Grid. The possibility of this happening is contained in the Moreton Plan which recognized that it could become outdated with the frequent reassessment required by the Act.

Our proposal is the connection of the Grid from Wivenhoe to the expanded storage of, and access to the raised yield of, the Borumba Dam. This will enable us to retain water now lost due to the inadequacies of the present system to cope with the retention of excess flood water. It is to be returned to the system when required. In addition there is access to further yield from the Borumba. The possibility of connecting the final stage from the Borumba to the Northern Interconnector will complete the grid with connections to all grid related dams in SEQ for storage purposes. The expanded storage of the Borumba will equate the entire capacities of all dams in SEQ and will be available to all dams in the grid system.

All of this adds to the availability of additional water in the Moreton system and for that mater all of SEQ. It makes sense and is in line with your efforts to find new water.

In our view there would have to be strong and detailed argument to counter this proposal. Your assistants have to, of necessity, be committed to the TCD.

End of extract 

The Minister's reply is on the home page of this website.

The reports provided in assessing the Inter Basin transfers between the expanded Borumba Dam and the Wivenhoe/Somerset system.

Index

* Introduction
* Clear understanding of the  McMah Proposal Stage
   three.      
* Approach by all three writers of these reports
   * Engineering
   * Hydrological
   * Finance

* Comments on all three reports including :-

* Stress - On the Moreton region
* Stress - The unwitting application of Bureau of 
               Meteorology statistics    
* Stress - Dam failure
* Stress - Release of stress for the Moreton region.

* Operation of the expanded Borumba Dam
* Backup material for the foregoing supplied in the Submission on the EIS ( Environmental Impact Study)

Introduction

The three reports we are about to review are classified as “assessments“. They are in response to the McMah proposal. They cover the areas of Engineering, Hydrology and Financial.  Mr Ron McMah refused to sign off on the terms of reference due to the Borumba Dam yield document showing 51,000ML annually and his requirement that the Engineers and Hydrologists be independent.

The Government had their selected Consultants proceed on a basis that appears to be “if there is something in it we will have another look”. In my view the assumptions made by the consultants differed to the main thrust of Ron McMah’s proposal. 

Their assumptions managed to block the Engineering assessment of the inter Dam transfers completely and provide a very heavy qualification to the same area in the Hydrology report. The Financial report was of no interest. They rendered much of what was written to be of little consequence.

Nevertheless it provides us with an excellent opportunity to eliminate the major blockages perceived by the Consultants in their assumptions. The opportunity for us to be concise presents itself as well as the opportunity to build on the positive aspects of the Hydrology report.

Clear understanding of the McMah proposal stage three

The main thrust of the McMah proposal was the use of the Expanded Borumba Dam in place of the proposed Traveston Dam. It was at this point that there was a convergence of objectives between us and I contacted Ron McMah. My objective was to gain control of "uncommon events" by harvesting their surplus water that now goes into Moreton Bay. This water will be returned at a time like the present and will not interfere in the long term with the 68% flow requirement at the Brisbane end of the Brisbane River Basin. To the contrary, you will see that this percentage is improved as you read the commentary of the the Hydrology report of Gilbert and Associates. 

You will have seen that I had the knowledge of the surplus water from “uncommon events” and Mr McMah had the receptacle to store them in the expanded Borumba Dam for temporary retention and return to their collection point in times of low water levels in the Wivenhoe/Somerset System. 

It was also my view that if these surplus waters, that now flow into Moreton Bay, were harvested, the Traveston Dam proposal could be eliminated and South East Queensland current water stress eliminated entirely for generations.

It became apparent, while reading these reports, that the purpose of the Expanded Borumba Dam in the McMah proposal was, for some unexplained reason, not clear to the writers of these reports. Central to his proposal was the construction of a wall at EL 230m so that the Dam would hold 2,000,000ML.

On the basis that the completed Traveston Dam proposal would produce a yield of 150,000ML, it would take 13 years to fill if there was no withdrawal from the Dam. Clearly the McMah proposal centred on his stage three being the transfer of surplus water from the Wivenhoe/Somerset system to the Expanded Borumba Dam and the transfer back to cover the large gaps in “uncommon events” being experienced from time to time in the Wivenhoe/Somerset System. .

Stage one and two of the McMah proposal was to examine the prospect of Weirs in the Mary Valley in conjunction with the “inter Dam transfer” and thus eliminate the Traveston Dam.

Unfortunately a great deal of these report resources were applied to the Mary Valley aspect which is of minor consequence.

Approach by all three writers.

JWP Engineering assessment dated January 2007.

We find that the engineering assessment of the inter Dam transfers has been placed in the “not to be pursued at this time” basket. The ball has been passed to the Hydrology assessment.

In the Executive summary E2 - Assumed Scheme operation

Investigations by G&A ( Gilbert and Associates Hydrology) have identified limitations into potential transfers from Brisbane River to and from an enlarged Borumba Dam, they include:-

1.     1.  the limits on extractions from the Brisbane River System currently proposed in the Draft Moreton Water Resource Plan which will result in a significant down rating of the amount of water that can be supplied by the Wivenhoe- Somerset system ;

2.      Relates to the Mary River

3.      Relates to transmission losses. (disputed)

It appears that they did not notice that it is the temporary storage of water over the spillway in which we are interested. It finds its way out into Moreton Bay and will be the only water to be stored in the Expanded Borumba apart from the Dam's normal inflow. Nothing will be drawn from the existing and stressed Moreton system which includes the Wivenhoe/Somerset system that is not ultimately replaced. To the contrary, water will be added to the system when required enhancing the 68% flow requirement at the Brisbane end of the Brisbane River Basin. 

You will also see later that the flood holding ability of the Dams will give the Engineers the time to transfer the surplus water over full supply level to the Expanded Borumba Dam.

Marsden Jacob Financial

There is no mention of the Transfer between Dams in this assessment and therefore has no bearing on the outcome.

Gilbert and Associates Pty Ltd – Appendix A. Preliminary assessment of potential for Inter-basin transfer.    

This is the only reference to the main aspect of the McMah proposal. It is presented as an appendix. The date is 17th September 2007 some six months after the Engineering non-report on the subject and listed above.

I have line listed this two page report so that we may more readily assess it. The original does not bear the identification of the Hydrologists or page numbers.

A review of appendix "A" of the Gilbert and Associates assessment and the reasons why I have arrived at the conclusions.

Gilbert and Associates Assessment of Inter-Basin Transfer ( Brisbane River and Mary River Basins .)

 (1)   This title, which may be technically correct, does not fully cover the intent.

 Conclusion:  Approximately 65% of the water in the Wivenhoe/Somerset System comes from the Stanley River . Refer to page 9 in this submission

(2) The McMah proposal Dam size

 Line 50/51. The size required under stage 3 of the McMah proposal ( between 1,500 and 2,000GL ) and ….

 Conclusion : The Dam required under the McMah proposal is clearly 2,000 GL. It is on page 1 of his submission to the Senate Enquiry which predates this assessment. This fact has an important flawed influence on conclusions drawn by them and graphs supplied by them. For example, the graph on dam levels was commenced at year 1900 instead of year 1890 which was the commencement of their simulated model. The 1893 flood would have filled the Dam to 2,000GL and the 1898 flood would have a further spill. Their graph commenced at 1,450GL thus altering the balance throughout.

Additional component of the McMah proposal

Line 2. Additional component. The Hydrology concentrated on the Mary Valley Weirs and the inter-basin transfers rated little mention particularly in the Engineering assessment and the cost assessment.

 Conclusion: One does not build a 2,000 GL Dam as an additional component. It is the main thrust of the McMah proposal

 The requirement for the Borumba to be overflowing before transfers could begin

 Lines 7 to 9. Transfer would occur from Borumba to Somerset/Wivenhoe during periods in which Borumba was overflowing and sufficient freeboard existing in the Brisbane River basin storages.

Conclusion: The capacity of the enhanced Borumba Dam is 2,000GL. The joint capacities of the Wivenhoe/Somerset are 1,165,000ML Wivenhoe and 380,000ML Somerset totalling 1,545,000ML. There is no apparent reason why this condition was placed on the transfer. The releases from the Borumba into the Mary Valley would be unaltered. The return transfer of the water to the Wivenhoe/Somerset System would contain all of the water withdrawn in times of major surpluses and released in times when “uncommon events” were absent and the Dams depleted as they are at this time.

Influence of large scale meteorological influences known by the Dam Managers as “uncommon events”

 Lines 49 to 54. The Borumba  catchment is relatively small ( approximately 465 km2 ) for a Dam required under stage 3 McMah proposal (between 1,500GL and 2,000GL) as such likely to fill and spill due to the influence of large scale meteorological influences which will almost always influence the Brisbane River catchment at the same time. As such Borumba is likely to be overflowing generally during those times in which Wivenhoe & Somerset are also close to Full Supply level.

Conclusion: This is an ideal situation to have on our hands. The Borumba enhanced to 2,000GL filled to overflow on numerous occasions and available to replenish the depleted Wivenhoe/Somerset when “uncommon events” depart for their quite normal walkabout. This absence creates gaps for several years, the last being 14 years 1974 to 1988.

 Unfortunately it is an elementary error if the DNR & W monthly stream discharge volumes at Yabba Creek are to be believed. They are available on the DNR & W website (since withdrawn) and I have reformatted them to show their influence on the Dam supply level. The highest peak was 1971 to 1975 when 1,091,290ML became available. The total for 1964 to 2002, 38 years, was 2,541,685ML.

 Draft Moreton WRP (Water Resource Plan)

Lines 68 to 83:  Based on NRW simulation modeling, under a scenario of full utilization of existing entitlements (i.e. full use of existing licensed extractions) there is little to no potential for additional extractions from the system without failing the MAF EFO of 68%.   Notes: NRW, Natural resources and Water:  MAF, Mean Annual Flow: EFO, Environmental Flow Objectives. The part of the System that we are dealing with is the Wivenhoe/Somerset and their catchments. The 68% is placed at the Brisbane end of the Brisbane River Basin .

 Conclusion: This statement fails to recognize that the System Dynamics have changed and that the required 68% is maintained and improved.

1.      The 80,000ML surplus water that goes over the spillway currently in times of “uncommon events” is to be transferred to and retained in the Borumba Dam and returned at a more suitable time. This gives no loss or gain.

2.      The Expanded Borumba Dam to 2,000GL now gives an annual yield of 91,000ML. After the normal release into the Mary Valley , there is approximately 75,000ML available annually thus giving us an equivalent net gain.

3.      The Grid system is designed to overcome some of the vagaries of “Uncommon events”. At 500ML per day capacity, there is an addition of most of this 182,500ML to the system. There is an annual net gain to the system of around 140,000ML after the Hinze Dam contribution is deducted.

4.       With the Grid system and Summer Rains providing approximately 1000ML per day, it is quite sufficient for our business as usual needs. However, with no draw-down required for a decade or two, there is no storage available for “uncommon events” when they return with the exception of the first event and possibly part of the second. The Summer rains have been quite normal for the last six years. The “worst drought in 100 years” is the product of a misused decile map with no uncommon events since February 2001 and normal summer rainfall. There were 5 events in the short life of the Wivenhoe Dam and we came to rely on them thus creating the observed stress on the Moreton Region. With 20 events in the simulated 111 years and a multitude in the last 60 years of the 19^th Century, they will return.

Because there is no storage space and no requirement to draw on them in the near future, a close run of uncommon events will mean that the major portion of them will be lost over the spillway of the Wivenhoe. The calculations of the last 30 years at Page 18 show that this concatenation (linking together) of events will provide a loss of 113,096ML a year over the spillway that cannot be retained in storage.

 With the blocking off of the Borumba Dam to a mere 40,000ML by the Traveston proposal, there will be no available space to contain these events. It will result in a gain to the Brisbane end of the Brisbane River Basin and a loss to the Wivenhoe/Somerset System of 113,096ML.  This loss should be calculated in the effectiveness of the Traveston thus reducing its supply to 36,904ML annually (150,000ML – 113,096ML).

Our proposal will collect most of this water but not all. It will occur at the same time as our proposed retrieval of the GHD identified surplus water of 80,000ML on an annualized basis. This will create pressure on the safety level of EL 74m and thus a considerable quantity may be lost. The capacity of the 2,000GL Borumba Dam will also be tested. This will create a gain to the system of a volume not yet determined and may be altered by the Engineers if they increase the pumping capacity.

The capacity of the enhanced Borumba Dam to 2,000GL provides a suitable buffer to the natural climate change of the first 70 years of the 20^th Century as evidenced in the charts provided in the addendum and the evidence of the Bureau of Meteorology flood information. It also provides defence against perceived climate change created by the exploding population of the World and its energy requirements. The Engineers GHD have identified the suitability of the Borumba for a wall to EL 320m which would retain most of the loss with suitable pumping gear.

Transfer from Brisbane river to Mary River

 Lines 55 to 66:  There appears to be no argument about the proposal for the transfer of water from the “ Brisbane ” River to the Mary Valley .

Therefore I will not offer scrutiny of the method employed. This section is added for completeness.

COMMENTS OF THE FOREGOING

Stress in the Moreton WRP region.   Engineering report; Hydrology report lines 68 to 83.

It is useful to examine the cause of the stress now being experienced in the Moreton Region.

SEQWater was formed as a “for profit” Corporation in 2000. A reading of their Annual Reports indicates that it set about expanding its customer base as one would expect any professional organization to perform.

The Annual report of 2001 provided a yield chart of 446,900ML for the Wivenhoe/Somerset system. There was an abundance of water to sell.

This is not surprising as you will see from this graph that 5 out of the 18 uncommon events in the last 109 years occurred in the years from the start of the Dam in 1986 to 1999 with a topup in February 2001.

The water allocation from the Wivenhoe Somerset found itself in this position. The yield in the SEQRWSS is quoted at 374,000ML.

Normal summer rainfall provides 182,000ML and the balance was made up by uncommon events. 

When Uncommon events depart, naturally the Moreton area is under stress. The drop in Dam levels above indicate Dam failure without intervention such as water restrictions and the "Grid".

The SEQwater yield, previously shown as 445,000ML, has been “under consideration” for some time.

The uncommon events that can fill the Dams in a few days ceased.

The summer rains that receive 50% of normal rainfall in 4 months and thus provide high impact were quite normal in both Dams in the 6 years to 2006. Any deficiency was in the non-summer months that normally provide little inflow.

There has been no “uncommon events” in the last 6 years. With 5 out of the 18 in the last 109 years and with the Dams full 4 times in the short life of the Wivenhoe, we had come to rely on them as an integral part of the water supply.

Stress on the Moreton region- The unwitting application of Bureau of Meteorology Statistics

The method with which the Bureau of Meteorology measures rainfall also played a part. It measures current rainfall against the thirty year period 1961 to 1990 and makes no exceptions for uncommon events. 

That period covered the year 1974 and its run-up as well as the events of April 1988 and April 1989 which filled the Wivenhoe from scratch. There has been no “uncommon events” in the 6 years to 2006 with a consequence that it will always show below average rainfall until a further uncommon event occurs.

As a consequence, SEQwater showed in their Annual Reports for the last 6 years “below average” or “well below average” rainfall. This is with almost normal summer rain and the discrepancy in the non summer months which rarely supply inflow.

A look at the actual rainfall stations in the Dams shows the long term average of the Bureau at below the 1961 to 1990 average in almost all cases.

Its decile map for the period gave birth to “the worst drought in 100 years” when all that really happened was that the “uncommon events” decided to take their break. The last break was the 14 years being 1974 to 1988. The uncommon events, or the lack of them, distort the application of the decile map.

The expectations of SEQWater in this chart, drawn from their own web-site and illustrated above, appears to support the conclusion that it was highly influenced by the 5 uncommon events in the short life of the Wivenhoe.

It is my view that this difficulty in understanding the actions of uncommon events is at the heart of our current problem. It took me many months to understand their influence on our water supply. The control over them through storage of their surplus water is the key to our future.

Stress on the Moreton region - Dam failure

We can clearly see, without the use of hydrological models, that the failure of the dam system without severe restrictions and without the water grid would have occurred in 2009 even with normal summer rain. Supporting this is the Government’s call for expression of interest to bulk supply the South East Region with water.  

The most recent August 2007 disturbance provided an extra 6 months. Enough time for the grid system to work in conjunction with the current (Dec 07 to Mar 08) above normal summer rains. You will see from my calculations that together they will supply our needs with the current strict water restrictions but have nothing further for growth in population or refill of the Dams.

Relief of stress in the Moreton region

Without our proposal for inter dam transfers, the Moreton region will remain stressed from time to time at the mercy of “uncommon events”. As explained, the last gap was 14 years with others as far apart as 22 years.

It is a long time for an ordinary “drought” to break.

The operation of the Borumba Dam incorporating lines 7, 8 and 9 of the report

Having the foregoing in mind, the position of the Expanded Borumba Dam becomes clearer. It is to be a holding dam for the surplus water that now goes over the spillway of the Dams including its own. Lines 55 to 66 seem to support the existence of this water and it will be examined in the next section. It has since been confirmed by the GHD Engineering desktop review in the Augmentation of the Wivenhoe Dam.

For this reason, lines 7,8 and 9 indicate that our intent has been misunderstood in the absence of a “Terms of reference”. The only external operation of the Dam is to act, as it normally does, supplying 35% of the water requirements of the Mary Valley which approximate 20,000ML per year from that source.

The intent is to fill the Borumba Dam to its expanded capacity when surplus water is available. It is withdrawn when conditions, such as we experiencing recently, exist.

We have seen that normal Summer rainfall and the Grid system combine to provide our basic restricted needs. All three stages of the Traveston Dam have a requirement to supply a total of 150,000ML annually. Their calculations are for the expansion of the population beginning in 4 to 6 years time and completed in some 20 years time.

A full Borumba Dam gives us 13 years supply and is fed back into the system via the Wivenhoe and Somerset Dams or some other similar method that the Engineers suggest.

Backup material for the above

The above material and other supporting information are largely contained in "Final Solution and the EIS".

Earlier assessments made by me have now been confirmed by official supporting data. There are no unsupported assertion. The backup material is available by a computer click.