More with Less? Sure, but...

Following the release of Pacific Institute's report "More with Less: Agricultural Water Conservation in and Efficiency in California", I had an email exchange with some of our farm advisors and agricultural constituency, and also with Peter Gleick, the lead-author on the study. The exchange addresses the question, whether saving water by increasing irrigation efficiency is a real savings - or rather a change in water allocation. Here we go:

October 17, 2008
Re: Pacific Institute Report "More with Less"

All:
A couple of you were wondering about the validity of last month's Pacific Institute (PI, under leadership of Peter Gleick) study entitled "More with Less: Agricultural Water Conservation and Efficiency in California". Attached (and listed below) are three very recent scientific articles that provide a more accurate perspective than some of the claims made in the PI study, in particular on the aspects of groundwater management in irrigated agriculture. It may provide some of you with talking points. Please read on for a short summary.

The PI study pointed to several valid issues on the future challenges and water management options that agriculture is facing in face of possibly dwindling water supplies in California. The study investigates four alternative water management scenarios associated with water deliveries from the Delta to the San Joaquin Valley. One of the key conclusions from the scenario analysis is that the "report provides a new vision of the Delta's future - one in which a profitable and sutainable agricultural sector thrives, while water withdrawals from the Delta are significantly reduced".

The study received a lot of press, because of headlines such as "agriculture could safe 3.4 million ac-ft of Delta water deliveries" and still do well. However, one - in my opinion - fatal shortcoming of the study's scenario analysis is the lack of considering direct impacts to groundwater storage from increased irrigation efficiency (where water quality is not an issue). I have been asked about this by a couple of you.

Attached are are three articles from a newly published Special Section in the journal Water Resources Research (WRR) on "Water Crisis in Irrigated Agriculture: How to Produce more with Less".  WRR is perhaps the most respected international scientific journal on water resources. The three articles are peer-reviewed. You may just want to
read the conclusions, abstract, and introductions (in that order of priority) of these articles. All three make a very important point: Higher irrigation efficiency does not automatically lead to water conservation.

I quote the first conclusion of Clemmens et al.: "Where irrigation water quality is good and deep-percolation returns to a freshwater aquifer, there may be little incentive, and sometimes disincentives, to reduce deep percolation".

And from Huffaker's conclusion: "Policy makers should exercise extreme caution in subsidizing improvements in on-famr irrigation efficiency for the purpose of conserving water. [...] Whether [...] encouraging improvements in on-farm irrigation efficiency can be expected to conseve water on a borader geographic scale is a complex question with
a wide array of possible answers." [...] "When runoff recharges fresh-water supplies in the basin, water conservation is accurately calculated as a reduction in consumptive water use and irretrievable water losses. In this case, reliable conservation generally requires
that farms consume less water either by irrigating fewer acres, switching to crops requiring less water, or irrigating current crops at a deficit."

For many of you, this is not really any news. But if you want to hand someone some information to balance the PI study with some equally fresh, and well respected news from the scientific community, here it is.....

Cheers,
Thomas

References:

Clemmens, A. J., R. G. Allen, and C. M. Burt (2008), Technical concepts related to conservation of irrigation and rainwater in agricultural systems, Water Resour. Res., 44, W00E03, doi:10.1029/2007WR006095.

Evans, R. G., and E. J. Sadler (2008), Methods and technologies to improve efficiency of water use, Water Resour. Res., 44, W00E04, doi:10.1029/2007WR006200.

Huffaker, R. (2008), Conservation potential of agricultural water conservation subsidies, Water Resour. Res., 44, W00E01, doi:10.1029/2007WR006183.

--

RESPONSE FROM PETER GLEICK (10/20/2008):
Tom,

I've just happened upon some of your recent comments about the Institute's latest study -- focused on the potential for improving the efficiency of water use without cutting production. I would have been happy to respond more quickly if you had sent them to me directly and it might have helped prevent misunderstanding or misreading of our report.

You decry our failure to assess the direct and specific impacts on groundwater from improved efficiency. You note "Higher irrigation efficiency does not automatically lead to water." We know -- you are criticizing a conclusion we don't make. We agree that it would be nice to have a comprehensive and integrated model that can tie efficiency improvements with very precise groundwater recharge, withdrawal, and quality models. DWR should have created such tools a decade ago. But they don't exist. And we are quite clear in our study that there is a significant difference between consumptive use and withdrawals, and we note that our scenarios save both, in different degrees that depend precisely on groundwater recharge, downstream use, and so on. As such, our "scenarios" are just that -- estimates of potential, not precise predictions of actual savings.

You also quote Ray Huffaker as saying "reliable conservation generally requires that farms consume less water either by irrigating fewer acres, switching to crops requiring less water, or irrigating current crops, at a deficit."  We understand this perfectly and agree. Indeed, two of these three things (crop switching and deficit irrigation) are precisely two of our four scenarios. We chose, however, NOT to include fallowing because it violates one of our key fundamental assumptions -- it reduces agricultural production. [Fallowing is inevitable in parts of the Central Valley, but we don't (and you shouldn't) consider it to be an improvement in "efficiency."]  If you have a better assessment of the potential of crop switching or deficit irrigation or better soil moisture management, we look forward to seeing it, particularly if you're able to couple it with region-specific groundwater dynamics.

In the end, though, perhaps you're missing the most important point of our analysis: There is significant potential to grow as much food as we are growing today while using less water. How much depends on very complex factors, but the potential for improved efficiency is not zero. Yet until our study, no one had done a comprehensive review of the options and tried to quantify some of that potential -- and in the absence of any assessments, the assumptions being made by DWR and others of the potential were not only low, but unreasonably and irrationally low, leading to no, or bad, policy. And even our conservative assumptions identify savings of only 5 to 15 percent of Delta water used by agriculture -- hardly out of the realm of possibility given the extensive experience of a growing number of farmers.  For example, our savings from crop switching still leaves 48% of the crops in the region as field crop (from today's 60%). Our assessment of deficit irrigation only applies to the small number of crops for which high-quality peer-reviewed studies are available to show a benefit. We do not switch any crop to tree crops, only vegetable crops. I could go on, but we tried hard to be conservative and to base our assessment on the actual experience of farmers who are already making these kinds of improvements.

Peter Gleick



Dr. Peter H. Gleick

President, Pacific Institute [20 Years of Research for People and the Planet: 1987-2007]
Member, U.S. National Academy of Sciences
MacArthur Fellow

654 13th Street
Oakland, California 94612
510 251-1600 phone
510 251-2203 fax

www.pacinst.org (Pacific Institute site)
www.worldwater.org (World Water site)

REPLY BY THOMAS HARTER (11/4/2008)
Peter:

My apologies for the delay in responding and - more importantly – for not including you in the circle of discussion in the first place. By the way, I much enjoyed the evening at annual GSA/TriSocieties in Houston a few weeks back. Unfortunately, there was no "call-in" line for listener questions, else you may have heard from me there....

Either way, I appreciate your comments and feedback to my notes on the Pacific Institute (PI) Study "More with Less: Agricultural Water Conservation and Efficiency in California". To both of us and many of those we work with, this is obviously an important topic. My role in sending the notes and article to the Scott Valley Water Committee, to some of my Cooperative Extension Colleagues, and to Mike Wade at the
SJF Farm Water Coalition was primarily one of responding to several inquiries regarding the state of science with regard to considering irrigation efficiency, consumptive water use, and applied water use.

Several of the concerns about the PI study have since then also been well articulated in the comments by Charles Burt, Peter Canessa, Larry Schwankl, and David Zoldoske, which I am sure you are aware of (see attached if needed). As you correctly noted, my specific concern lies with the lack of a thorough analysis of the groundwater management
component associated with the scenarios you analyzed. In my opinion, the PI study lacked an appreciation of the impacts to groundwater resources. Yet, our ability to recharge, store, and bank water in aquifers is not only an already important part of California's water management scheme, it will only become more important - I think we
both agree on that.

Let me speak to your points one-by-one (your notes are indicated by a
">" mark at the beginning of the line).

> On Mon, Oct 20, 2008 at 2:06 PM, Peter H. Gleick <pgleick@pipeline.com> wrote:
> Tom,
>
> I've just happened upon some of your recent comments about the Institute's
> latest study -- focused on the potential for improving the efficiency of
> water use without cutting production. I would have been happy to respond
> more quickly if you had sent them to me directly and it might have helped
> prevent misunderstanding or misreading of our report.
>
> You decry our failure to assess the direct and specific impacts on
> groundwater from improved efficiency. You note "Higher irrigation efficiency
> does not automatically lead to water." We know -- you are criticizing a
> conclusion we don't make. We agree that it would be nice to have a
> comprehensive and integrated model that can tie efficiency improvements with
> very precise groundwater recharge, withdrawal, and quality models. DWR
> should have created such tools a decade ago. But they don't exist. And we
> are quite clear in our study that there is a significant difference between
> consumptive use and withdrawals, and we note that our scenarios save both,
> in different degrees that depend precisely on groundwater recharge,
> downstream use, and so on. As such, our "scenarios" are just that --
> estimates of potential, not precise predictions of actual savings.

The PI Study makes a number of important conclusions, many of which I fully support and some of which are the underlying driver for much of our cooperative extension and research work, and of my work as board member of the California Groundwater Resources Association. I particularly agree with your conclusions regarding the need for
sustainable agriculture, providing incentives for water conservation, strengthening the efforts to promote use of appropriate irrigation technologies, improved assessment of agricultural water use (see attached our 2003 Independent Panel report on Appropriate Measurement of Ag Water Use), and the expansion of education and training.

Both, DWR and the U.S. Geological Survey have been and still are engaged in developing comprehensive modeling tools to look at groundwater-surface water interactions. Elsewhere, the joint efforts by Jay Lund, Richard Howitt, and Marion Jenkins (UC Davis) in their CALVIN project  (http://cee.engr.ucdavis.edu/faculty/lund/CALVIN/ )
have long sought to take such a comprehensive look across the entire state of California. Remarkably, they find that the state as a whole works rather efficiently in its distribution of water. Dr. Lund and I have also worked on further exploring in more detail the connections between surface water and groundwater in the Tulare Lake basin (for example Marques et al., 2006). Besides CALVIN, there are other relatively comprehensive and integrated models available that can tie efficiency improvements with groundwater recharge and/or groundwater quality in the San Joaquin Valley - our own work in Tulare Count (Ruud et al., 2004) or the work by Dr. Hopmans' group on Westside salinity, which ties closely to water quality (Schoups et al., 2005), to name
just two examples.

My statement that "Higher water efficiency does not automatically lead to water conservation" refers to the specific conclusions drawn by the authors of the three papers that I had included in my short note. It does not quote a conclusion in your report. However, it does refer to the fact that reductions in water application through improved irrigation management (three of the four PI Study Scenarios) do not necessarily lead to overall basin conservation of water (which the PI study does conclude).

The PI study makes very little mention of groundwater. On page 15, the report acknowledges the return flow to groundwater from excessive water applications, but only to make the point of the time delay thus affecting the stream ecosystem. Groundwater pollution and groundwater management are mentioned, but a specific conceptual framework is missing for the PI's study scenario analysis. On page 23, the study acknowledges that there is not a 1 to 1 relationship in water water use reductions and Delta withdrawals due to surface and groundwater return flows. Indeed, the report states "As already noted, consumptive use reductions are especially valuable." But there is no systematic attempt in the evaluation of the scenarios to take such understanding into account. Without accounting for groundwater storage changes, the scenario analyses have little basis for concluding anything about possible San Joaquin Valley (basin) water savings that would allow for effective reductions in Delta water deliveries.

On page 27 and Table 4, the study has another misleading example that lacks accounting for groundwater storage changes.  The report states that the 1.2 MAF in water use decline due to the modest crop shifting scenario would more than exceed the 1.1 MAF of groundwater overdraft. Presumably the statement implies that if this scenario is  implemented,  this would alleviate the groundwater overdraft problem. The 1.2 MAF in
water savings is assumed to stem from lower ET on vegetable crops that replace field crops (p.23) on a certain amount of acreage.     

However, the groundwater overdraft would only be alleviated if the external surface water deliveries to the three basins remain the same, that is if there is no simultaneous reduction in Delta water deliveries to the San Joaquin and Tulare Lake basins. The benefit of the 1.2 MAF of savings has to either be allocated to fixing the groundwater overdraft problem or the Delta water deliveries, but cannot do both - that would be double accounting. Yet, the conclusions that the report draws in its executive summary (see above) only mention the benefit of reducing Delta water deliveries and are silent
on the remaining groundwater overdraft issue.

> You also quote Ray Huffaker as saying "reliable conservation generally
> requires that farms consume less water either by irrigating fewer acres,
> switching to crops requiring less water, or irrigating current crops, at a
> deficit."  We understand this perfectly and agree. Indeed, two of these
> three things (crop switching and deficit irrigation) are precisely two of
> our four scenarios. We chose, however, NOT to include fallowing because it
> violates one of our key fundamental assumptions -- it reduces agricultural
> production. [Fallowing is inevitable in parts of the Central Valley, but we
> don't (and you shouldn't) consider it to be an improvement in
> "efficiency."]  If you have a better assessment of the potential of crop
> switching or deficit irrigation or better soil moisture management, we look
> forward to seeing it, particularly if you're able to couple it with
> region-specific groundwater dynamics.
>

By quoting Huffaker, I did not mean to imply an endorsement of fallowing. I do have ideas of how to include groundwater into an analysis such as yours and would be happy to discuss that.

> In the end, though, perhaps you're missing the most important point of our
> analysis: There is significant potential to grow as much food as we are
> growing today while using less water. How much depends on very complex
> factors, but the potential for improved efficiency is not zero. Yet until
> our study, no one had done a comprehensive review of the options and tried
> to quantify some of that potential -- and in the absence of any assessments,
> the assumptions being made by DWR and others of the potential were not only
> low, but unreasonably and irrationally low, leading to no, or bad, policy.
> And even our conservative assumptions identify savings of only 5 to 15
> percent of Delta water used by agriculture -- hardly out of the realm of
> possibility given the extensive experience of a growing number of farmers.
> For example, our savings from crop switching still leaves 48% of the crops
> in the region as field crop (from today's 60%). Our assessment of deficit
> irrigation only applies to the small number of crops for which high-quality
> peer-reviewed studies are available to show a benefit. We do not switch any
> crop to tree crops, only vegetable crops. I could go on, but we tried hard
> to be conservative and to base our assessment on the actual experience of
> farmers who are already making these kinds of improvements.

I have not argued - and few would - that there is a zero potential for improved efficiency. There are valid reasons to increase irrigation efficiency and change irrigation management strategies, not only from a water management point of view, but also from a water quality point of view. The regulatory landscape in Calilfornia is about to make a
major shift towards significantly more monitoring of agricultural return flow water quality not only to surface water, but also to groundwater (I am referring to current activities in the Central Valley Regional Water Quality Control Board regarding the Irrigated Agriculture Waste Discharge Waiver). This will inevitably have significant implications on irrigation management. I disagree with your point, however, that "no one had done a comprehensive review of the options and tried to quantify some of that potential." I refer to the extensive comments provided by my colleagues Charles Burt  et al. (see attached), who cite a number of studies and reviews that have been produced by varies agencies and institutions that are addressing the question of agricultural water efficiency. In particular, the Davenport and Hagan (1982) analysis provided substantial insight into the question that the PI report is addressing.

I welcome any further opportunities to discuss the PI study.

Regards,
Thomas Harter


References:

Charles Burt, Peter Canessa, Larry Schwankl, and David Zoldoske, Agricultural Water Conservation and Efficiency in California - A Commentary -, October 2008
Independent Panel on Appropriate Measurement of Agricultural Water Use, Convened by the California Bay-Delta Authority, Final Report, September 2003. (DOWNLOAD)

Marques. G. F., J. R. Lund, M. R. Leu, M. Jenkins, R. Howitt, T. Harter, S. Hatchett, N. Ruud, and S. Burke, 2006. Economically driven simulation of regional water systems: Friant-Kern, California. J. Water Resour. Planning and Mgmt 132(6):468-479. DOI:
10.1061/(ASCE)0733-9496(2006)132:6(468)

Ruud, N. C., T. Harter, and A. W. Naugle, 2004. Estimation of groundwater pumping as closure to the water balance of a semi-arid irrigated agricultural basin. J. of Hydrology 297:51-73.

Schoups, G., J.W. Hopmans, C.A. Young, J.A. Vrugt, W.W. Wallender, K.K. Tanji, and S. Panday. 2005. Sustainability of irrigated agriculture in the San Joaquin Valley,  California. Proc. Natl. Acad. Sci. 102:15352–15356