180/400 GSP Amendment Chapter 6 draft

[Thomas S. Virsik]

The within comment is based on the materials available for the 6 January 2022 180/400 Committee meeting.  Chapter 6 was not addressed at the meeting and will be on the agenda of a later special meeting.  Nevertheless, please note the following concerns based on the material as published:

The overall comment is that certain implicit math involved in the multiple water budgets (in the draft Chapter and in the PP) lack integrity.  The premise of these comments is that a water budget is at its core a series of inputs and outputs or  positive and negative values that result in a sum or delta seen as a gain or loss.  

Page 192 contains a historical water budget where math suggests the delta is more than a negative 30K. The future water budgets on page 193 reflect even greater deltas of approximately negative 46 and 49 K.  Those delta or summation values are not included in the water budget presentations, however (the same chart data appears in several other locations).

Page 229 (Table 6-13) from draft Chapter 6 shows the future water budgets, this time with a storage loss sum of a negative (loss) of 600 -- orders of magnitude different than what the math reflects.  The notes to Table 6-13 explain that model error was unacceptably high and thus one can conclude the 600 was not a model-generated value, but I have been unable to find how the 600 delta was actually calculated.  Leaving aside issues of accuracy of the model or of the 600 figure, Table 6-13 comes across as unreliable or worse.  That the model is not sufficiently accurate (so far) is one thing, but a "600" af loss in a table that reflects tens of thousands of acre-feet of deficit even on a casual glance is jarring.  

The narrative at page 230 about the historical overdraft of 600 - even if taken at face value -- does not provide justification for concluding it must be the same number when the inputs and outputs substantially change in the future.  The tables and lack of explanation challenge credibility that the same loss occurs when conditions change in the future, especially when that is not true for other GSP's.

That the projected loss may in reality be closer to some amount of thousands is highly germane to considering projects and actions in later chapters, not to mention implementation issues such as costs and feasibility of design and financing.  To fix a 600 AAF problem one may need only to impose nearly imperceptible controls on overall water use whereas a loss of thousands requires different tools.

I urge the GSA to review especially the projected water budgets and their seemingly arbitrary reliance on a value chosen when considering a different set of inputs and outputs.  Also or in the alternative, the justification for the 600 number may need to be better detailed and then applied, if justified, to the future water budgets.  

Thank you for your consideration. 

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Thomas S. Virsik

Attorney at Law

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Alameda, CA 94501

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