You can get roughly 75% of human water use in agriculture being agricultural in several ways, some from DWR and others from reading reports by local agencies and backing out water use from pretty well-understood fundamentals (like crop net water use rates, acres of crops, populations, and urban per-capita use rates). The numbers vary a bit with your assumptions, of course, but pretty much any reasonable estimate shows agriculture being the largest human use of water in California, by a fair bit. Many such estimates are a bit squishy, which is not surprising, but they provide some insights anyway.

Here is the email from Dr. Hanak at PPIC where she states she got the 75% figure from DWR. She also provides a link to a PPIC publication:

Thanks for your interest in our work. You can find a more detailed discussion of this information in chapter 2 of our recent report, Managing California’s Water: From Conflict to Reconciliation (available at: http://www.ppic.org/main/publication.asp?i=944). The original data is from the Department of Water Resources. Please let me know if you have any other questions.

I am not sure about your characterization of my review of your review as “mostly correct.”

I remain convinced by the water rights holder case you and Mike Wade make, but am now less so about the 75% figure, given that you and Dr. Hanak cite the same sources (DWR) but get different numbers. I’ve elaborated at my website in response to you, and perhaps you can clarify. Like I wrote, I enjoy reading how people use numbers to support their conclusions.

Other conclusions you make seem to be more in the realm of ideological difference (you might say the cultural and political) than they are of numbers. In those cases it seems to me to be more a question of what one prefers than what one knows.

But anyway…

Also, as I hope anyone who carefully looks at the content of my website would understand, I am most definitely not a Delta preservationist.

John is an architect and preservationist who doesn’t hide where he is coming from and his blog deserves a serious read. Here are his comments [Note:I have added some follow up clarification in CAPS]:

CalWatchDog’s blog has the supply sider argument in a 
refutation by Wayne Lusvardi of a recent piece by pragmatist Peter Gleick on California water myths.

Mr. Gleick’s post is titled “Myth of California water shortfalls,” and Mr. Lusvardi’s response “No shortage of water mythmakers.” Gleick’s sums up his basic argument thus: The real problem: The assumption that all water users can have all the water they want all the time and that when 100 percent of such expectations cannot be met, something is wrong.

Mr. Lusvardi disagrees, and implies, we think unfairly, that the sources of funding support Mr. Gleick’s Pacific Institute receives are good reason to question the legitimacy of his motives. One can question motives, of course, but whether Mr. Lusvardi likes them or not, Gleick’s motives seem pretty straightforward. [TO CLARIFY: I DON’T QUESTION DR. GLEICK’S MOTIVATIONS OR FUNDING, BUT HIS BOARD IS ALL GREEN – WL].

We here at the DNP think Gleick is just expressing a political opinion held by many people, which he certainly has every right to do. And as a pragmatist, he understands that there is little political will to spend the kind of money Lusvardi’s position would entail if implemented. Especially given the many competing claims for that money.
To his credit, Mr. Lusvardi cites some data that call into question some of Gleick’s numbers on water use and other assertions. And since we have used some of the myths Lusvardi calls into question, we thought it would be fair to give him an airing.

Lusvardi’s rebuttal is broken down into the following categories, listed below with commentary:

Mythical “Not Enough Water”
Gleick: Not enough water to go around
Lusvardi: The problem is capture, storage and treatment
DNP: $$$

Mythical Eight Fold Water Rights
Gleick: Eight times as many water rights given away as there is water available
Lusvardi: (via Mike Wade) Multiple permits for the same water only mean that we are efficiently using it over and over again.
DNP: Lusvardi’s and Wade’s argument seems truthier

Mythical 75 percent of water goes to agriculture
Gleick: Does not mention this here, and a quick search finds that it is the PPIC who most recently made this claim
Lusvardi: Cites DWR guys who says it’s more like 43%
DNP: Always enjoy reading people use numbers in support of their position. Very important in the political theatre. Though we are open to more knowledge on this, for now, Lusvardi’s DWR guy makes his claim seem truthier.
[I CONTACTED DR. ELLEN HANAK AT PPIC AND SHE SENT ME AN EMAIL SAYING SHE GOT THE 75% NUMBER FROM DWR! SO THE 75% NUMBER IS MORE AN ACCEPTED RUMOR THAN A PROVABLE FACT – WL]

Mythical claim that drought was good for agriculture
Gleick: Cal agriculture broke all $$ records during drought
Lusvardi: West side farmers (or, as he puts it, “one California valley”) didn’t participate enough in the windfall.
DNP: Take west side farmland out of production. It is toxic, literally and politically. Pay them off.

Mythical No More Money for Large Water Projects
Gleick: No money, no political will, no environmentally acceptable sites for dams, etc.
Lusvardi: $18.7B in water bonds gone to fund greenbelts and open space in wealthy northern California enclaves.
DNP: We could be wrong, but seem to recall that Mr. Lusvardi lives in Pasadena, or near there.

Mythical species extinction
Gleick: Driving fish, plants and other wildlife to extinction
. Lusvardi: Value the downstream habitats of rose gardens, lawns and warm water fish. 
DNP: Salmon tastes much better than catfish. And by the way, environmental and scientific agendas are also cultural and political.

Mythmaker
Gleick: There isn’t enough water to go around
Lusvardi: Property rights
DNP: Myths are incredibly powerful stories

Declinist
Gleick: There isn’t enough water to go around
Lusvardi: Yes there is, if we spend tens of billions to capture,
store and treat it—and return to the political culture of the 1940s.
DNP: Population growth intensifies scarcity issues. Thoughtful people develop complex views, and generally understand the difference between what the world is, and what they wish it to be.

Mike Wade
California Farm Water Coalition

The Declinist Paradigm mentioned in my article and in the book review cited in the above comment (“Denial Is A River in California”) is the Establishment paradigm of water in California, despite facts to the contrary.

Laer if you know a sponsor willing to underwrite a book on California water using a different paradigm please let me know.

http://www.amazon.com/review/R2SA6ENC716NQ/ref=cm_cr_dp_perm?ie=UTF8&ASIN=0230615643&nodeID=283155&tag=&linkCode=

There is a “flood” (pun intended) of recent water books out by elite experts all embracing the “declinist” paradigm. A “Declinist Paradigm” is reflective of zeitgeist (spirit of the times) when money, not water, is in short supply. See book review for a list of recent water books.