Random Groundwater Notes

Too Much Regulation in California Agriculture?

2011-02-04T23:19:00.000-08:00

Too many regulations, contradictory regulations, too much paperwork, rules that are way too complex, compliance costs that are out of proportion with benefits - such sentiments are echoed by some of our cooperators and what I hear in (often groundwater-related) farm meetings, particularly with respect to the dairy industry. What do we do about it?

I would second - from my own experience - the problem of non-communication/mis-communication/non-coordination between local and state agencies, between local and local agencies within and between counties, and between state agencies, each bringing its own personality and expertise to the table. The worst is the same state agency with the same rules, but different offices, or different officers enforcing different standards - the California Regional Boards being one example often cited.

On the other hand, I also see that there is often little understanding (and not seldom little effort to understand) by the landowners/farmers for the admittedly complex environmental issues that agriculture is naturally embedded in.

This is not always the fault of the landowner, often this is an issue of a lack of available extension/training - and sometimes the "solution" is simply not handy. For dairies more so than for other farming, the issue of ignorance/education/lack of information is furthermore a structural issue: given that the dairy industry is indeed still primarily a family farming business (which the general population is strongly supportive of, as opposed to "corporate" ag business), the (technical/intellectual/human resources) capacity of the entrepreneur are necessarily limited as leadership comes largely out of the existing family. Yet, a dairy is really not unlike a city with a mind-boggling array of issues needing increased attention in a policy climate that requires attention to economic benefits, ag-urban/consumer relations, and ag-environmental relations: animal health, animal reproduction, animal management, nutrition, food quality, food safety, waste management, forage production, irrigation, air quality, water quality, pest control,.....

In this last decade a number of stars have aligned in an unprecedented manner "against" agriculture: the 2002 sunset on discharge waivers granted to nonpoint source dischargers under the Porter-Cologne Act, EPA TMDL enforcement (which is mostly targeting nonpoint source surface water polluters) stepped up, air quality and global change issues coming to the forefront of global politics and science funding, microbial source identification and public health reporting systems now capable of detecting food illness outbreaks and tracking to their sources with ever increasing accuracy and detection sensitivity.

Combined, this has put enormous regulatory pressure on agriculture in ways that other economic sectors first experienced in the late 1960s through 1980s as the US and Europe began regulating environmental impacts.

I sense that we are only at the beginning of a major revolution of doing agricultural business. Environmental regulation will increase, not decrease, as the need for sustainability in agriculture becomes more apparent, better defined, and agricultural management practices advance. It will take a couple of decades to sort this out both, at the farm/owner/business level and at the regulatory landscape/agency level. The challenge of nearly doubling global food production over the next three decades will put yet another spin on this. Some farmers ask to role back the overwhelming amount of regulation. The key question, however, is how we can cut through the current seemingly chaotic jungle of regulations most efficiently toward a streamlined version, without sacrificing the intent of the legislative framework in place.

Answers to this question must correspondingly address both, the farm management/business operations level and the regulatory level.

While it seems daunting, the upshot of working through this headache is that California has an opportunity to lead in creating a new agriculture model for the US and globally - and that California, in the process of doing just that, will be creating knowledge and technical experience that is exportable and will create new business opportunity not only for the state's ag engineering, ag consulting, etc. businesses, but also for the state's agriculture.

This said, one comment I have also heard from cooperators is this: environmental regulations are not the issue - as long as they apply to everyone equally, i.e., as long as the playing field is level. This points to the issue of compliance cost in California vs. other states. Once California has figured out how to run agriculture in an environmentally sustainable manner and within an effective and efficient regulatory framework, California's task needs to be to see the latter exported across the country. If we are demonstrably successful with creating an effective, yet streamlined regulatory framework for agriculture, I imagine the political forces will be such that nationwide adoption would follow suit as it has with so many other things in the past - that should be an additional incentive for the regulatory/planning agencies at the state level to do their share towards such streamlining.

One major obstacle in the way of streamlining regulation is the lack of funding for a systematic, centralized and comprehensive regulatory approach to agriculture that is not unnecessarily burdensome to the individual farm. Not only is the regulatory landscape highly balkanized, so is agriculture itself. With the state broke into the foreseeable future, the public's lack of interest in raising either taxes or fees, the funding is being raised within each of the little fighting blocks. Hence, each little block wants its own say in how the money is spent to set regulation on one hand, and to (minimally) comply with regulations on the other.

An example: the dairy industry just barely passed an industry-wide vote to tax itself to create a dairy groundwater monitoring coalition. Funding is raised to install a regional monitoring well network on a select number of dairies through this coalition in lieu of the state dealing with a monitoring well network on each of 1,400 dairies. The network is intended to be expanded in the future. The idea is to intensively monitor management practices on a number of dairies to define successful management practices (with success measured by groundwater monitoring wells). A consulting firm is currently working on the network design and presumably will be evaluating the results.

In contrast, in Holland, a national research lab associated with their national EPA, has installed an extensive soil and groundwater monitoring network on over 1,000 farms across Holland, all of which are part of a group of 6,000 farms that report detailed numbers about their business/farm management practices to the federal ag statistics service. The networks were designed by scientists and are sampled, analyzed, and evaluated by scientists of the national lab. Trends, relationship to farm practices, etc. are scrutinized, recommendations prepared, which then go to the national ag department and the legislature, which sets five-year frameworks for regulations regarding farm management practices.

Our challenge is then, perhaps, not only to define a more unified/streamlined approach toward regulation, regulatory compliance, and enforcement in agriculture, but - just as important - to define a funding model that gets rid of the balkanization on both sides. Do we need to look to Europe for learning some of that?

Water Movie Ideas

2010-08-23T12:35:00.000-07:00

Ron Duncan, manager for the Soquel Creek Water District and columnist for his local paper, the Santa Cruz Sentinel is suggesting some cool water related videos that are fun to watch and provide lots of water-related food for thought. I am copying his article in today's Santa Cruz Sentinel below, including links. Movies are also part of how undergraduates are introduced to water science on the UC Davis campus. My colleague Greg Pasternak, for example, is teaching an entire class "Water and Popular Culture" around water-related movies (see table below). And for another good groundwater quality story (besides "A Civil Action"), don't forget "Erin Brockovich' 2000".

*WATER IN MODERN AMERICAN SOCIETYScience and Society, Undergraduate Course***PROF. GREG PASTERNAK, UC DAVIS
Week 1
Week 1		Chinatown
Week 2		Discussion:Water Scarcity
Week 2		The River
Week 3		Discussion:Water, Race, and Socio-economic Class in America
Week 3		A Civil Action
Week 4		Discussion:Water Quality in America
Week 4		Into The Wild
WATER IN WORLD CIVILIZATION
Week 5		Discussion:Self Psychology, Externalization, and Environment
Week 5		Aguirre, Wrath of God
Week 6		Discussion:Tropical Wilderness, Water, and Native Peoples
Week 6		Burden of Dreams
Week 7		Discussion: Movie makers and the environment
Week 7		The Fast Runner
Week 8		Discussion:Arctic Wilderness, Water, and Native Peoples
Week 8		Day After Tomorrow
Week 9		Discussion:Global Climate Change
Week 9		The Bridge on the River Kwai
Week 10		Discussion:Water, Transportation, and War

Go Green, Ron Duncan: Water films still making a splash
Posted: 08/21/2010 01:30:15 AM PDT

Water-related films like "China Town" and "Step Into Liquid" are popular for their entertainment value, but they also can provide awareness and an oblique appreciation for water.

However, as local and global water shortages start to show their strain on society and the environment, there has been a surge of videos and films that explore and address these water issues in a more direct fashion. These films range from short, well-done postings on "YouTube" to full-length professional productions. They are usually designed to educate and deliver the full impact of an issue related to the world's or a given region's water situation, often containing astounding footage and facts.

Below is a variety of recommended water films, with a type of film for just about everyone. See if you can find one that fits your pleasure.

Cadillac Desert' 1996
Starting with my personal favorite is the film "Cadillac Desert: Water and the Transformation of Nature." This film is a four-part documentary about water, money and politics in western America, with a segment focusing on how Los Angeles grew. Most of the film is based on Marc Reisner's seminal book "Cadillac Desert," which is a great read. The film is available for purchase online, but several intriguing clips can be seen atwww.videosurf.com/cadillac-desert-71015. This documentary combines the best of entertainment and education.

Chinatown'1974

Chinatown is a Hollywood classic that portrays the darker side of how Los Angeles obtained water from Owens Valley. Roman Polanski directed and actors Jack Nicholson and Faye Dunaway star. If you have trouble untangling all the dealings in this film, watch the first series of Cadillac Desert for full enlightenment.

Poisoned Waters' 2009
This PBS documentary looks at how many of America's waterways are in jeopardy from pollution and contains excellent interviews with some of the nation's environmental experts. View free atwww.pbs.org/wgbh/pages/frontline/poisonedwaters.

Blue Gold: Water Wars' 2009
"Blue Gold" was recently shown by the Santa Cruz nonprofit Coastal Watershed Council. It focuses on privatization and control of the world's water. Human struggles for water are displayed, including a scene where a person takes his own life to demonstrate the importance of water. This movie does not make for a light evening, but it is educational. Available at www.bluegold-worldwaterwars.com.

Step Into Liquid' 2003
This dynamic and rhythmic surfing film was called "spiritual" by The New York Times. It is not only a great surfing documentary, but a film where a genuine appreciation of water is forefront. Visit www.stepintoliquid.com.

California Water' 2006""2008
Comprising 24 episodes, this series is like taking a road trip through the water veins of California. The series took four years to complete. Production was sponsored by the Association of California Water Agencies. The series contains basically everything you could want to know about water issues in California. It is available for purchase and will soon be posted for free viewing at www.calgold.com/water.

State of Thirst: California's Water Future' 2008
This well-done KQED video visually summarizes how pressures on water supplies are increasing. View atwww.kqed.org/quest/television/state-of-thirst-californias-water-future.

Waterworld' 1995
Yes, this is a full-on Hollywood extravaganza. What makes it unique is the futuristic setting in a world flooded with water and all the land submerged. It's a provocative view of too much of a good thing.

Flow' 2008
This award-winning documentary focuses on the privatization of water and the world water crisis, but also interviews people that are implementing solutions. Available for purchase at www.flowthefilm.com.

California Colloquium on Water' ongoing
For those of you who can not get enough about water, this lecture series is for you. The Colloquium water website contains about 75 video lectures from scholars of distinction discussing various aspects of water and related issues. This is one of my favorite water-related film websites and is found atwww.lib.berkeley.edu/WRCA/ccow.html.

River and Tides' 2002
This documentary, recommended by my artistic wife, shows the ephemeral work of the talented Scottish artist Andy Goldsworthy. Many scenes illustrate the tension between time and water, leaving one awestruck. It is available for purchase online and has made appearances at the Nickelodeon Theatre in Santa Cruz.
Whether you are seeking pure entertainment value or are looking for a more educational documentary regarding water, any of the above films get two thumbs up.

Ron Duncan writes a biweekly column for the Sentinel. He is a manager for the Soquel Creek Water District, which offers free visits to homes and businesses and suggests ways to save water. Contact him atrond@soquelcreekwater.org or call the District at 475-8500.

Toward Sustainable Groundwater in Agriculture - Linking Science with Policy

2010-06-20T00:45:00.000-07:00

...that was the title of our international conference this week in Burlingame/San Francisco. Complete with pre-conference workshops and a post-conference tour of lovely Sonoma Valley and it's dairies and wineries. The conference was an amazing gathering of movers and shakers, thinkers and tinkerers, decision-makers, policy makers, planners, farmers, ag-industry representatives, consultants, students, even high-school students, and researchers. Attendees came from California, from across the United States, and from around the globe - Asia, Africa, Europe, Latin America, Australia. All had one thing in common - a shared interest in groundwater resources of agricultural regions and in agriculture's role in sustaining groundwater resources for future uses in agriculture and for other uses.

If you want to get a flavor for the information from the conference - Michael Campana blogged about the meeting this week (thank you, Michael!) - he was one of our final panelists. And here are my own personal - and much drier - "classroom notes" from the conference, covering about a quarter of the presentations. Mind that these are unedited and I am not guaranteeing either completeness nor accuracy! Vivian Jensen generously provided her notes as well.

Groundwater depletion and groundwater degradation, how much we know about it, how we assess and monitor that, how we regulate (or not regulate) and manage it, and what we can learn from each other in protecting groundwater resources for future agricultural and other uses - these were the main themes of the conference. The program speaks for itself and we will have the many resources generated at the conference, including abstracts, presentations, and selected videos available at the conference website by August 2010. A special journal issue will be in preparation shortly.

This was a gathering of a unique (and very fun!) group of people, many of whom had never met before. But many of us found that we had much to share and learn from each other.

As co-chair of the conference, I am deeply grateful to the program council for their enthusiasm, creativity, and tireless efforts in planning and putting together an impressive speaker list; to my executive conference committee, Rita Schmidt-Sudman and Sue McClurg from the Water Education Foundation and Cathryn Lawrence from UC Davis, to the wonderful folks at the Water Education Foundation (Jean Nordmann, Diana Farmer, Rebecca Scott, Robin Douglas, Susan Lauer, Beth Stern), and to my students Katie Lockhardt, Reid Bryson, Tyler Hatch, Tomer Schetrit, and Vivian Jensen for the hard work needed to make this conference possible on the organizational end and for ensuring that the meeting itself went so very smoothly; to the session chairs for their confident guidance through a packed and tightly orchestrated program; to the speakers for the high quality of their presentation and the shared inspiration for their work; to the audience for their lively and engaging discussions; to the conference sponsors for their financial support (University of California Davis College of Agricultural and Environmental Sciences, Erler and Kalinowski Inc, Kings River Conservation District, and GEI Consultants, and - indirectly through travel support - UNESCO and FAO); and to the Groundwater Resources Association for their help in bringing exhibitors and visitors to the conference.

Food and Fuel Consumption the Biggest Environmental Stressors

2010-06-05T21:22:00.000-07:00

Today is World Environment Day. On that occasion, UNEP (United Nations Environmental Programme) this week released a report "Assessing Environmental Impacts of Production and Consumption" (press release: here, also in The Guardian). The report looks at the compound environmental impacts for human health, ecosystem health, and natural resources from industrial/agricultural production and also from a human consumption point of view. The report concludes that use of fossil fuels and consumption of foods have the most significant environmental impacts including impacts on the availability and quality of water resources:

• "Agriculture and food consumption are identified as one of the most important drivers of environmental pressures, especially habitat change, climate change, water use and toxic emissions.

• The use of fossil energy carriers for heating, transportation, metal refining and the production of manufactured goods is of comparable importance, causing the depletion of fossil energy resources, climate change, and a wide range of emissions-related impacts."

Importantly, the report suggests that increasing wealth in developing countries leads to increased environmental impact in large part because of the change to increased meat and dairy consumption that comes with economic improvements in developing countries (in addition to the increased fuel consumption). A major conclusion of the report is that a global change in our diet, away from meat and dairy consumption, is needed to lessen the large strain on environmental resources, especially land and water resources (also see The Economist special on water).

Interestingly, the report, on p. 82, makes a further note on the ambivalent role of biofuels and on the yet to be researched feedbacks between energy use, biofuels, water, and ocean water desalination (see my blog on solar power vs. biofuels):

"A final issue that needs attention, particularly when developing policy solutions related to the problems above, is to understand the linkages that can be identified between the different types of pressures on resources and the environment. [...] Another connection is identified between energy and water. Future energy supply, even with a modest contribution of biofuels, may have a huge water requirement, which certainly is not included in estimates of future water use. The energy requirements for water supply are also expected to rise, when the easily accessible freshwater supplies are overdrawn and large scale desalination of seawater might become necessary. These and other linkages are hardly identified yet and even less quantified and modelled. They are nevertheless of great importance for sustainable development policies."

The report underscores the acute timelines of taking a close look at the food-feed-fiber-(bio)fuel-connection with groundwater sustainability in agriculture, which will be the focus of "Toward Sustainable Groundwater in Agriculture", 15-17 June 2010 in San Francisco. Clearly, the system/policy complexity and dynamic feedback between food security, which is at the core of human well-being, safe drinking water and sanitation (another key human health aspect), agriculture, and ecosystem health and specifically groundwater resource use, management, and sustainability is still largely unexplored. That's why I am very excited about the conversations at this upcoming conference.

By the way, a great resource on water and water management in agriculture (at a global scale) is the "Comprehensive Assessment of Water Management in Agriculture". And if you are specifically interested in learning about groundwater in agriculture around the world, your best - and probably only comprehensive - resource is Mark Giordano and Karen Villholth's phantastic book "The agricultural groundwater revolution" (17 chapters).

For want of a drink

2010-05-23T11:56:00.000-07:00

...is the title of a phantastic special issue on water in the Economist this week. An absolutely worthwhile read, front to back, for anyone interested in a primer on the global context of water, drinking water, sanitation, food production, water scarcity, water pollution, water management, and water politics and its importance to the planet's livelihood and survival. The report touches on all the important areas and does it well, REALLY well! The author, John Grimond, is to be congratulated to this series. This is the best thing "water" in the general media that I have ever seen, when it comes to providing an overview of water issues around the globe. It is an extremely timely article. It comes just ahead of our conference on "Sustainable Groundwater in Agriculture: An International Conference Linking Science with Policy", 15-17 June 2010, in San Francisco. Conference speakers include a number of the experts that John consulted with in preparation for his articles.

From my perspective - and related to several of the notes below - kudos to John Grimond also for making a successful effort to convey the hydrologic concept of "consumptive water use" (water that goes to evapotranspiration) in contrast to non-consumptive water uses (e.g., water down the kitchen sink), for pointing out the importance of agricultural water use and its link to feeding the world, for getting it right on the importance of crop ET, and for the clever integration of groundwater concepts into this whirlwind tour of global water.

Here is a list of links to the individual articles:

Pathogens, Water, and Animal Agriculture

2010-05-19T14:46:00.000-07:00

This week, I am participating in a USDA funded workshop at beautiful Cornell University to discuss waterborne disease occurrence, management and control in agricultural regions. The workshop, put together by Cornell University with funding from the USDA, brings together regulators and industry experts with pathogen researchers across various disciplines that have been funded over the past five years under the National Institute of Food and Agriculture research program. The workshop is peppered with a number of very interesting overview presentations related to waterborne disease. The talks are very accessible to the public and I highly recommend them if you are interested:

Jeffrey Griffiths - Outcome of Waterborne Disease Infections
Jane Hill - Moving Bacteria
Dwight Bowman - Disease from Recreational Water
Rob Atwill - E.coli O157:H7 Outbreaks in California's Leafy Green Industry
Jeanine Plummer - Drinking Water Quality and Disease Outbreak
Jim Smith - Managing Infectious Organisms from Animal Farming Operations
Chuck Gerba - Viruses: Sources, Occurrence, Fate and Risk Assessment
Ron Fayer - Cryptosporidium
(or go here to find links to the above talks)

Also check out this EPA Review of Detecting and Mitigating Fecal Contamination from Animal Agriculture.

Should We Bother?

In my small workgroup, we are discussing various aspects of the risk of waterborne illness exposure in drinking water, recreational water, or on (fresh) foods due to contamination of waters (groundwater or surface water) from animal farming (beef, dairy, poultry, swine). A lot of brainstorming and learning across disciplines (sitting at the table with a couple doctors that are experts on gastrointestinal diseseases, epidemiologists, an ag industry representative, veterinarian, animal scientist,...).

The specific framework we are looking at are animal farming operations (confined or not) on one hand, and what I would call "beneficial uses" and what a colleague here has referred to as "exposure points" on the other hand: drinking water sources (public/private water supplies, that is, surface water intakes, groundwater wells), recreational water (pools, ponds, lakes, rivers, beaches), and fresh food crops (e.g., salad, spinach, tomatoes) that are irrigated with water or treated with manure. Pathogens may travel between the two (farm/ranch to exposure points) via air, soil, surface water, or groundwater or any combination thereof. [Note: our workshop focuses on farm/ranch sources; there are many others related to human activities and to wildlife.]

The big three words that came up in our discussion today are risk assessment, risk management and policy (e.g., the four-barrier approach to mitigating pathogen transport in manure management), and risk communication (including education). Together, these constitute a risk analysis. Risk management and communication/education happens at both ends of the framework: on the farm/ranch side where manure is produced (manure and animal management, farm education and extension) and on the exposure/water use side, where the infectious transmission to humans potentially occurs (water treatment, public education). It can also occur as part of the treatment and education of infected people (for a good laugh, see this No Crypto commercial).

It is well known (and at UC Davis we have down our own share of work on dairies) that pathogens such as E. coli O157:H7, Salmonella, Campylobacter, Cryptosporidium parvum, can be present in animal manure. I have always assumed that controlling pathogen release from animal manure into waterways would intrinsically have a public health benefit. But of course there are many sources other than farms and ranches for waterborne, gastrointestinal diseases, and there are many pathways for transmission other than water for farm fecal pathogens to infect people (think: petting farm, farm camp,....) - see my cartoon above.

As a result, we have an endemic level of these diseases in the population. An interesting question to ask is this: at a national level, if we were to perfectly "sterilize" all manures produced on animal farms before any of it enters a surface or groundwater, would we indeed see a difference in the occurrence of gastrointestinal diseases (the main form of waterborne disease)? Jeff Griffiths from Tufts University pointed us to two interesting publications that show the correlation between animal farming and waterborne disease prevalence (frequency) at a national or large regional level:

Jyotsa Jagai and co-workers recently published a national public health study that shows the relationship between cattle density (cattle are a source of the pathogen Cryptosporidium parvum) and the prevalence of Cryptosporidium infections (so-called cryptosporidiosis). The study convincingly shows that the average occurrence of reported protozoan infections is approximately one-third higher in U.S. counties with high cattle density than in areas with low cattle density. Importantly, the study does not assign risk to specific pathways (water, air, direct contact), so it would be wrong to conclude that waterborne disease occurrence is higher in cattle farming regions than elsewhere. It is indeed a possibility.

Another finding of this study is - in counties with high cattle density - that the occurrence and outbreak intensity of protozoan infections in areas with low population densities (i.e., the country-side) is different from areas with high population densities (i.e., urban areas near/around cattle farms): in rural areas, the outbreaks are more pronounced and spike in the fall, while urban areas experience a more steady infection rate that spikes in the early summer. One hypothesis that I would pose is that this may be the result of the different water sources in these two groups (if drinking water indeed is the main transmission pathway): in rural areas, most water comes from domestic wells (groundwater), whereas most urban areas are on public water supplies, many of which come from surface water sources. How would that affect the timing of disease outbreak? Beef cattle calves (the main source of Cryptosporidium) are typically born in the spring, spring is also a time of much runoff. Hence, surface water sources probably carry the highest pathogen load in late spring and early summer. That same peak would be attenuated in groundwater recharge and not show up in domestic wells until later in the year. Hence rural households wouldn't see a peak in protozoan disease incidence until the fall.

Note that many domestic wells pump water that is much, much older than six months, but that water is unlikely to carry infectious pathogens, since few pathogens survive longer than half a year.

A more conclusive answer on the important role of the waterborne pathogen transmission specifically from animal farming was described in an English study: Sopwith and co-workers showed for northwest England that animal manure management practices (and - at a later time - additional treatment of the drinking water supply) suppressed a well-known re-occurring annual late spring/early summer outbreak of animal-related (zoonotic) Cryptosporidium parvum infections. Annual late summer incidences of human-caused Cryptosporidium homini infections (e.g., via public pools, lakes) remained high during the same time period tested.

These kind of regional/national public health studies on factors controlling the prevalence of waterborne disease are still rare, yet very important in understanding and communicating the national and international importance of animal manure management to reducing the risk of pathogen transport into waterways and ultimately to substantially reduce waterborne infection rates in human populations (see Drs. Griffiths' or Bowman's talks above for all the gory details on waterborne diseases - only bug people can have these kind of dinner conversations... :-).

Scrap Irrigated Biofuel Crops & Plant Solar Farms!

2009-12-05T01:45:00.000-08:00

After thinking some more about the numbers in yesterday's blog, here is a revolutionary idea: take irrigated biofuel crops already existing in the sunny Southwest (including California) out of production and put solar farms on those fields instead. Why? With no additional land used, we'ld have more energy in the grid, less chemicals in groundwater, less groundwater overdraft, and/or water leftover for the rest of us (including the rest of agriculture).

How is that going to work?

Let's start with some numbers on corn, currently the main source of ethanol fuel:

2009 California corn acreage: 550,000 acres
2009 Arizona corn acreage: 45,000 acres
2009 New Mexico corn acreage: 140,000 acres
2009 Utah corn acreage: 65,000 acres
--------------------------------------------------------------
2009 total Southwest corn acreage: ~ 800,000 acres
2009 Colorado corn acreage: 1,100,000 acres

2009 United States corn acreage: 86 million acres
2009 United States ethanol corn acreage: ~ 22 million acres (25% of total corn acreage)
2009 United States irrigated ethanol corn acreage: ~ 1-2 million acres (based on 2003 USDA statistic about the percentage of irrigated ethanol corn - I would guess it is actually higher now. In fact, a recent Argonne National Lab report, p. 3-27, estimated the irrigated fraction of biofuel acreage to be "less than 10%").

How much of the 800,000 acres of Southwest corn is used for ethanol - I am not sure, but it is probably not 25%. In California, much of the corn acreage is used to produce sileage for the California dairy industry (which produces more then one-fifth of the U.S. cheese and milk). Even if not a single acre of Southwest corn was used for ethanol and all of it went to sileage on Southwest dairies: I speculate that with the same subsidies that are currently used to ship Midwest corn to Western U.S. ethanol plants, we can ship corn from the Midwest to Southwest dairies to replace the needed sileage.

My point is: whatever corn acreage in the Southwest we convert to solar farms, we can replace the lost sileage for dairy production by taking some of the ethanol-destined corn from the Midwest and then using it for sileage in lieu of energy production. Looking at the numbers, we still end up with a net gain in energy - and a net gain in water!

Whether it is actual biofuel corn that is bulldozed over or whether it is sileage corn that the dairies replace with Midwest ethanol-corn-turned-dairy-sileage, let's assume that we can achieve a 1:1 replacement of 2009 ethanol-corn acreage with solar farm acreage. Using the water and land use intensity values mentioned in my last blog, here are a few basic energy systems scenarios and their water and land use benefits:

Scenario 1. Realize the total solar power currently planned for the Southwest - by converting corn fields to solar farms.

We would need to convert the sunniest 100,000 acres of the current irrigated corn acreage in the Southwest (approximately 13% of the current Southwest corn acreage) into solar farms to generate approximately 12,000 MW of energy. I wouldn't be surprised if those 100,000 acres aren't already used for growing irrigated biofuel corn in the Southwest! Another perspective: 100,000 acres would be 20% of the irrigated acreage in sunny Imperial Valley.

Benefit:
5 times more energy per converted acre (land use intensity is five times lower for solar than for biofuel)

700 times less water use: Of (approximately) 230,000 acre-feet of water evapotranspired on 100,000 acres of irrigated corn (see.e.g., our paper, Table 1 ), less than 2,500 acre-feet would be needed to dry-cool the solar-farms. The other 227,500 acre-feet of water would be available for other uses.... (assuming all solar farms are of the dry-cooled variety).

Scenario 2. Generate 100% of the electricity used in CA, AZ, NM, CO, and UT with solar farms, 450 million MWh (in 2007; US Total: 4,100 million MWh).

The installed solar power to generate this much energy would have to be on the order of 300,000 MW - six-hundred solar farms of 500 MW each - and 4,000 acres each. Together, these farms would need approximately 2.4 million acres of land. That is 120% of the combined corn acreage in the Southwest and Colorado. This acreage is also just about equal to the total U.S. acreage that is currently irrigated to produce ethanol (see above)!!

Benefit:
Over 10% of 2007 U.S. electricity demand generated from renewable solar on one-tenth of the land currently in use for ethanol production.

Assuming that 80% of that land comes out of currently irrigated corn production, with a consumptive use of ~2.3 acre-feet/acre, the amount of water savings is 4.5 million acre-feet - enough to meet more than one-third of the total urban and industrial water demand in these five states.

Furthermore, assuming an average energy use of 1 MWh to produce 1 acre-foot of groundwater or surface water (from a very enlighteningand article by Dana Larson and others at the Bren School, UC Santa Barbara), an additional 4.5 million MWh of energy are saved every year.

Scenario 3. Replace the entire current U.S. acreage of ethanol-corn with solar farms.

Well, I am not sure about the efficiency of solar plants in much of the Midwest (where most ethanol-corn is grown), when compared to the Southwest, but at 10 times more land than in scenario 2, that ought to get us perhaps five times the amount of energy of scenario 2 or close to 50% of the total U.S. electricity use in 2007 - with the potential to replace all natural gas plants (22% of U.S. electricity) and half of all coal-powered plants (coal-powered plants produce half of the U.S. electricity). And we would save at least all the irrigation water of scenario 2 and then some.

But we would loose all the ethanol - can we use the natural gas saved in the process instead? Natural gas produces 900 million MWh of energy in the U.S (in 2007). On the other hand, 22 million acres of displaced ethanol-corn, at 178 bushels per acre, and with 17 bushels of corn to make 1 MWh, are worth 230 million MWh. We just gained four times the energy on the same land!

So no kidding: take out the ethanol corn (and perhaps not just the irrigated variety), and bring on the solar farm!

No doubt, these are hypothetical scenarios - there are a lot of other questions to ask and challenges to address (e.g., new crop distribution to take advantage of where the sun is, transportation systems adjustments, electricity transmission, carbon cycle impacts, economic impacts on farming regions, aesthetics of corn fields vs. solar panels) - but the big picture numbers cannot be argued away. Perhaps a key limitation is the ability of our national energy grid to deal with such large penetration of an intermittent energy source. With smart adjustments to our current grid, about 20% - 30% of our energy mix could come from an intermittent source such as solar (also see Denholm & Margolis' article in Energy Policy, 2007).

The most intriguing aspect of this comparison is that it is based on a replacement of one type of renewable energy-crop with another renewable energy "crop" - on the same currently used land - at five times the output, millions of acre-feet of (ground)water saved, and a lot of potential groundwater and surface water pollution from ethanol-corn production avoided (my main motivation to look at these scenarios). [Also check the numbers in this article].

Can we figure out the incentives needed to make this work in a free-market economy?

==========================
Addendum, 15 March 2010:

A very good friend of mine is working on environmental impact reviews for solar power plants in Arizona (how did all my friends get into solar so suddenly?). She pointed out yet another technology in the array of concentrating solar power (CSP) technology: reflector dishes with Stirling engines, currently brought to market by Stirling Energy Systems. These systems use no water (perhaps for washing the mirrors?) and require little land preparation (according to my friend, the pole supporting the dish is simply and quickly rammed into the ground). Each dish has a 25kW engine and two proposed facilities (Solar One in Calico and Solar Two in Imperial Valley) would be 8,200 acres for 850 MW and 6,500 acres for 750 MW, respectively - approximately 10%-15% more landuse intensive than the 4,000 acres for 500 MW cited and used in my recent blog (which I used as the basis for the above computations).

Wow - what a concept! These SunCatchers(TM) seem (to a naiv academic at least) to be the perfect crop for business-savvy farmers to put into their overall crop rotation. Here is a proposal for a great water and solar farm:

The farmer leases the land to folks like Stirling Energy Systems (SES) that will install ("grow") SunCatcher(TM) dishes on the farm fields to replace the ethanol corn, while the farmer keeps watering the underlying barren land as part of an intentional water recharge project - without the farm chemicals (fertilizer, pesticides) and without the salinity increases in groundwater recharge from irrigated ethanol corn or other agricultural crops. The heavy equipment for land preparation and dish installation is already on the farm anyway, the infrastructure for the recharge project (in surface water service areas) is already in place, including water rights, delivery canals, and distribution system. And the apparently "simple" installation of the SunCatcher(TM) means that the farmer doesn't need to buy into this technology forever. The lease could be for a few years. SES could move the dishes to another site for the next lease period (so it does NOT have to look like this)

The question is only - can it be done to give the farmer something around a $500/acre net income, which is the average net farm income in CA - about 10 billion dollars on 20 million acres. According to "Agriculture Online" somewhere between $300 and $500/acre is also the net income generated for a typical corn farmer at 178 bushels/acre (see my recent blog) at 2009 corn prices of $4/bushel - also confirmed by the USDA economic statistics on corn.

On the water market side, a California farmer could generate something on the order of one to a few hundred dollars per acre by recharging from one to five acre-feet of water into a groundwater bank, if (s)he sits in the right location for groundwater banking. Some farmers already do this by simply fallowing their land for so-called in lieu recharge arrangements.

On the solar energy side, a California farmer would need to be paid about $2 per MWh - above and beyond any cost for renting, installing, and maintaining the SunCatchers(TM) - to generate $400 net income per acre annually (I am using the solar land use intensity of 5 acres/1,000 MWh that I presented in my recent blog). That is 0.2 cents per kWh for those of us household customers used to paying about 10 cents per kWh. In other words: to make this work for a farmer, Stirling Energy Systems and other companies need only pay a small fraction of the price that the generated energy is worth to pay the farmer some rent on her/his land. And if they increase the rent/lease offer (say 0.5 cents/kWh instead of 0.2 cents/kWh) - then (I assume) it would be a real incentive for the farmer to go solar, since (s)he is now looking at net earning of $1,000/acre.

....now I just need to find my 100 acre farm...(and cut a deal with SES). I'll let my friends chime in on the hurdles to pass the EIR. Perhaps I can claim SunCatchers(TM) to be just another crop - then, as a farmer, I would not have to implement a cumbersome EIR at all!!

Some of these solar power projects will be going in very fast under ARRA - this could become a model for installing solar power projects on current ethanol corn (or other agricultural) fields. A very interesting (but in total acreage limited) option is to build solar (CSP) facilities on already disturbed non-agricultural land that is not used otherwise (former mining sites, brownfields, etc.) - check out the "Restoration Design Energy Project" in Arizona. For a huge longer term project with a fast track pilot, check out LA Water & Power's Owen's Valley solar project.

Last, but not least, Derek Abbott just published a fine review of global energy alternatives - and the Stirling dishes are his favorite alternative.

==========================
Addendum, 9 January 2010:

A comparison of land coverage (square meter per GWh generated) for a number of different energy sources, including coal, wind, solar, and biofuels, was recently published by Vasilis Fthenakis and Hyung Chul Kim in "Renewable and Sustainable Energy Reviews". The article confirms the conclusion above.

Similarly, below is the abstract of a related article that compares energy-solutions based on environmental impacts. The article "Review of Solutions to global warming, air pollution, and energy security" is by M. Z. Jacobsen, Energy & Environmental Science 2(2):148-173, 2009.

This paper reviews and ranks major proposed energy-related solutions to global warming, air pollution mortality, and energy security while considering other impacts of the proposed solutions, such as on water supply, land use, wildlife, resource availability, thermal pollution, water chemical pollution, nuclear proliferation, and undernutrition. Nine electric power sources and two liquid fuel options are considered. The electricity sources include solar-photovoltaics (PV), concentrated solar power (CSP), wind, geothermal, hydroelectric, wave, tidal, nuclear, and coal with carbon capture and storage (CCS) technology. The liquid fuel options include corn-ethanol (E85) and cellulosic-E85. To place the electric and liquid fuel sources on an equal footing, we examine their comparative abilities to address the problems mentioned by powering new-technology vehicles, including battery-electric vehicles (BEVs), hydrogen fuel cell vehicles (HFCVs), and flex-fuel vehicles run on E85. Twelve combinations of energy source-vehicle type are considered. Upon ranking and weighting each combination with respect to each of 11 impact categories, four clear divisions of ranking, or tiers, emerge. Tier 1 (highest-ranked) includes wind-BEVs and wind-HFCVs. Tier 2 includes CSP-BEVs, geothermal-BEVs, PV-BEVs, tidal-BEVs, and wave-BEVs. Tier 3 includes hydro-BEVs, nuclear-BEVs, and CCS-BEVs. Tier 4 includes corn-and cellulosic-E85. Wind-BEVs ranked first in seven out of 11 categories, including the two most important, mortality and climate damage reduction. Although HFCVs are much less efficient than BEVs, wind-HFCVs are still very clean and were ranked second among all combinations. Tier 2 options provide significant benefits and are recommended. Tier 3 options are less desirable. However, hydroelectricity, which was ranked ahead of coal-CCS and nuclear with respect to climate and health, is an excellent load balancer, thus recommended. The Tier 4 combinations (cellulosic-and corn-E85) were ranked lowest overall and with respect to climate, air pollution, land use, wildlife damage, and chemical waste. Cellulosic-E85 ranked lower than corn-E85 overall, primarily due to its potentially larger land footprint based on new data and its higher upstream air pollution emissions than corn-E85. Whereas cellulosic-E85 may cause the greatest average human mortality, nuclear-BEVs cause the greatest upper-limit mortality risk due to the expansion of plutonium separation and uranium enrichment in nuclear energy facilities worldwide. Wind-BEVs and CSP-BEVs cause the least mortality. The footprint area of wind-BEVs is 2-6 orders of magnitude less than that of any other option. Because of their low footprint and pollution, wind-BEVs cause the least wildlife loss. The largest consumer of water is corn-E85. The smallest are wind-, tidal-, and wave-BEVs. The US could theoretically replace all 2007 onroad vehicles with BEVs powered by 73 000-144 000 5 MW wind turbines, less than the 300 000 airplanes the US produced during World War II, reducing US CO2 by 32.5-32.7% and nearly eliminating 15 000/yr vehicle-related air pollution deaths in 2020. In sum, use of wind, CSP, geothermal, tidal, PV, wave, and hydro to provide electricity for BEVs and HFCVs and, by extension, electricity for the residential, industrial, and commercial sectors, will result in the most benefit among the options considered. The combination of these technologies should be advanced as a solution to global warming, air pollution, and energy security.

Coal-CCS and nuclear offer less benefit thus represent an opportunity cost loss, and the biofuel options provide no certain benefit and the greatest negative impacts.

Water and Land Use Intensity of Solar Power vs. Biofuels

2009-12-04T18:06:00.000-08:00

In continuing to grasp some basic land use and (ground)water use issues associated with energy production, it occurred to me during some recent discussions with my wondeful friends and colleagues Stephen Kaffka, Dan Putnam (both UC Davis), Margot Gerritsen (Stanford), and Wayne Spencer (Conservation Biology, San Diego) to compare the water intensity of solar power (see blog below) with that of another renewable energy source: biofuels. In the Southwest, all three (food&fiber production, biofuel production, and solar power) compete for land and water. Comparing water use and land use of a solar farm and an ethanol-corn farm in the Southwest on a per MWh-basis is not going to be favorable for biofuels, I figure - given all that irrigation water. But how bad is it?

In my recent blog, these are the numbers that I cited for solar power:

Water intensity: 35 gal/MWh - 175 gal/MWh (dry-cooled)

Land use intensity: 4,000 acres for 500 MW. Assuming an annual production of about 800,000 MWh from a 500 MW installation (I am going by the efficiency of my own new solar panels at home), this equals a land use intensity of 5 acres/1000 MWh (annual production).

To estimate water and land use intensity for ethanol produced from irrigated corn (perhaps the worst case of biofuel water intensity), I am using numbers from a report to Congress (p.61-62):

Irrigated corn needs an average (all of the U.S.) of 1.2 acre-feet irrigation water per acre and has an average yield of 178 bushels per acre. The average consumptive water use on irrigated corn in the U.S. is 2,200 gallons of water per bushel, ranging from 500 gal/bushel for Pennsylvania to 6,000 gal/bushel for Arizona (also see, e.g., this recent journal article by Stanley Mubako and Chris Lant at Southern Illinois U., and another by Andy Aden). Given typical ethanol production rates from corn and ethanol energy content, that is 2,500 to 29,000 gal per MMBtu (million Btu) - see the Figure below. 1 MWh equals 3.414 MMBtu. Hence, at 178 bushels/acre, we have

Water intensity: 730 gal/MWh - 8,500 gal/MWh
Land use intensity: 8 acres/1000 MWh (back calculating, e.g., reciprocal of 6,000 gal/bushel * 178 bushel/acre / 8,500 gal/MWh)

If the ethanol was used in a thermo-electric power plant, and assuming a typical efficiency of thermo-electric plants of about 30% (a number typically found for coal power plants), we have the following water and land use intensities:

Water intensity: 2,200 gal/MWh - 25,000 gal/MWh [+300 gal/MWh in consumptive use at the plant]
Land use intensity: 25 acres/1,000 MWh (annual production).

Michael Campana, aka Aquadoc, just a few weeks ago, listed a number of reports on the topic of water use in biofuels. The bottomline is that biofuels grown from irrigated crops in the Southwest or California have an enormous consumptive water use intensity. And their land use intensity is significantly higher than that of solar power farms.

This is not to argue against the use of biofuels (see my next blog). The use of both renewables, solar energy and biofuels is a matter of much more than water use or land use. For example, at low irrigation rates, biofuels could be generated in water positive fashion even by desalination of salt water (which takes a lot of energy). The issue of water and land use in the biofuel production is certainly not new and much has been written about it. There are alternative biofuel sources that are much less water intensive. Dana Larson and her colleagues at the Bren School, UC Santa Barbara, recently published a wonderful summary on the water usage in energy production, related policy issues, and current policy requirements. Quoting from the above-mentioned Report to Congress (p.44):

"[...] biofuel feedstock produced from crop residues in excess of those needed to maintain a healthy ecosystem, from feedstocks grown without irrigation, or from feedstocks grown with nontraditional water, will have minimal freshwater use intensity associated with production. This could provide significant volumes of bioenergy and biofuels in the future with low water use intensity (Perlak et al., 2005). In all cases, some water use is associated with processing, as shown in Figure V-4, but further technology development is likely to lower these values." [Figure below from the same page]

Surviving (Mega-) Droughts - Of Course on Groundwater!

2009-11-02T03:21:00.000-08:00

Two speakers with real world examples on the role of groundwater in today's world of drought preparedness followed Scott Stine's talk in a session on managing drought, held at this year's Biennial Groundwater Conference. Dr. Behrooz Mortazavi, Eastern Municipal Water District (EMWD), and Gary Serrato, Fresno Irrigation District, explained the many elements of their respective district's conjunctive use management approaches.

EMWD receives nearly half of its water from the State Water Project (drought!!), one quarter from the Colorado River (more drought!!), 13% from groundwater, 2% from desalination, and almost 20% through recycling. For anyone interested in seeing the many elements of water management and particularly of groundwater and conjunctive use management applied and systematically integrated into a single framework - this is a story not to be missed (which is why have very much enjoyed Behrooz' presentations at our introductory Groundwater & Watershed Hydrology shortcourses in Southern California).

EMWD has it all: high TDS (brackish) groundwater, low TDS groundwater, expanding urban areas, agriculture and animal farming, drought, large dependence on imported water, a complex array of groundwater basins with interconnected groundwater flow, local groundwater overdraft, cities, private landowners, federally reserved water rights associated with tribal lands, urban groundwater contamination, nonpoint source contamination of groundwater... for just about any issue from a Groundwater (management) textbook, there is a real world example to be found in EMWD.

Working for decades with a diverse group of stakeholders and partners within its service area, EMWD has implemented a wide array of groundwater management measures: extraction monitoring, water quality monitoring, a well abandonment program, water recharge projects, tertiary treatment of municipal waste water for recycling as irrigation water in lieu of groundwater, a desalination project to manage its brackish groundwater, close cooperation with its tribal partner. Listening to Behrooz, this seems like a textbook example of groundwater management and drought preparedness - why wouldn't everyone do it this way? Behrooz is not shy pointing out the decades of work it took to bring the district where it is today - through extensive stakeholder participation, negotiation, and education. (Behrooz' presentation can be found here).

Gary Serrato manages the Fresno Irrigation District (FID), which receives most of its surface water from the Kings River and is part of the Kings River Conservation District, supplemented with water from the San Joaquin River through the Central Valley Project (CVP, Friant-Kern Unit). The district overlies a large groundwater basin, part of the Central Valley aquifer system. Joint use of groundwater and surface water has been practiced in FID nearly from its beginnings, I suspect long before the term "conjunctive use" became popular. FID includes a varied agricultural landscape - citrus orchards in the far eastern portion, tree orchards and vineyards throughout much of the central part, and cotton and other field crops further west. The cities of Fresno and Clovis and several smaller communities are also part of FID and receive a significant amount of water from FID. For over four decades, the City of Fresno and Clovis have used surface water to recharge their (overdrafted) groundwater (e.g., "Leaky Acres" facility, numerous recharge basins located throughout the city for intentional recharge). Their treated wastewater has also been used to recharge groundwater for many decades.

New to FID's portfolio is the Waldron Groundwater Banking facility near their south western boundaries. While Leaky Acres is in the middle of the City of Fresno's own groundwater cone of depression (recharge directly into the groundwater use area), Waldron is intentionally designed for banking purposes, with water users not necessarily overlying the bank (see Gary's presentation).

Agriculture has played a significant role in FID's historic and often unintentional conjunctive use program - recharge from irrigation, particularly in wet years, recharge from recharge basins scattered throughout the Kings River basin, which are filled in the spring for groundwater recharge, and groundwater use during drought periods have been a traditional and intrinsic part of water operations in FID. What I have found most interesting about this for the many years I have known Fresno County: Unlike the recent conjunctive use schemes that I know from Arizona and Southern California, which have been well-studied designs associated with intensive hydro(geo)logic and water quality studies prior to build-out, much of FID's and KRCD's conjunctive use program have been around for half a century or more - for as long as Pine Flat Dam (on the Kings River) and Millerton Lake (on the San Joaquin River) have been around; Until recently, they have been driven by large scale, intuitive design at the surface water management level, without any guidance from detailed groundwater basin studies or modeling efforts.

This has recently changed, with "business as usual" in groundwater management quickly disappearing throughout California. Given the history of water and groundwater use, the politics in Fresno County are not any easier than in EMWD's service area. No less than 28 agencies have recently come together to develop an Integrated Regional Water Management Plan. Much of the water management issues and (ground)water use history is - perhaps for the first time - extensively described in the associated documents generated by the IRWMP, including an extensive groundwater modeling study.

Surviving Mega-Droughts - on Groundwater?

2009-10-30T01:18:00.000-07:00

At the recent California Biennial Groundwater Conference, I was assigned to chair a special session on "Thriving (or Surviving) in Times of Drought". Scott Stine, California State University East Bay, opened the session with his fascinating story and review of California's medieval mega-droughts. He is known perhaps mostly for his discovery and age-dating of old tree stands hidden below the surface of Mono Lake until recent water diversions to LA substantially lowered the lake level. At the meeting, Scott unfolded a story of varied evidence from many more places - from Point Reyes at the Pacific Coast to Walker Lake and Pyramid Lake in the Great Basin - that consistently tell of large mega-droughts, one between approximately 900-1100 AD and another from approximately 1200-1350 AD.

In fact, it turns out that the first half of the 20th century - the hydrologic time period used by engineers as a basis to design our large Western U.S. water projects - was one of the wettest periods not just in the Colorado Basin, but also in California's climate history of the last two millenia. Tree stumps from periods of when lake levels in California were climatically low - sometimes well below current day discharge elevations - are found not just at Mono Lake, but also in Donner Lake, Fallen Leaf Lake, and Tenaya Lake, to name just a few. For entire forests of large trees to grow well below today's lake level of, for example, Tenaya Lake, weather in California must have been much drier than today - not just for three years, but for decades and centuries.

Scott took us on an amazing detective's journey of evidentiary materials for these mega-droughts, followed at times by mega-wet periods: Sierra's alpine meadow wetlands and geologic records of plant stands, ancient soils, lake shore levels, flood sediments, juxtaposed against time markers, such as known volcanic eruptions leaving behind widespread layers of ashes or tuff - scattered across California and neighboring states. The droughts were long and deep - Mono Lake was perhaps 50-60 ft (15 - 20m) below its early 20th century lake level, well below even its recent, man-induced low-stand.

It is a stark reminder of California climate's variability, even before global warming. Importantly, groundwater appeared to have played a critical role for some plants and animal species to survive these mega-droughts: using pupfish as an example, Scott pointed out that species may have survived over generations in and near springs of Eastern California, fed by groundwater. Thus, these species celebrated a major comeback during wetter climate conditions, despite the fact that their habitat had almost completely been destroyed by drought. It is a concrete, if mostly metaphoric success story from which we may wisely take our cues as we manage an always uncertain water future in California: groundwater is an essential part of our water landscape.

Inconvenient Truth: Some "Green" Energy Can Guzzle Water

2009-10-09T00:27:00.000-07:00

...that was the title that the Davis Enterprise used for Todd Woody's recent NY Times article exploring a recent surge in solar projects and a recognition of the need for sometimes significant amounts of water being consumed by large-scale commercial solar power plants. The title caught my eye. Being a numbers guy by nature, I was wondering what this article may be calling a "guzzler". The lead example for the article (and associated blog) were two planned solar farms in the Amargosa Valley (right next to Death Valley). Annual consumption would be 1.3 billion gallons of water per year. Sounds like a lot of water, doesn't it? I prefer to use cubic meters or acre-feet and compare it to equivalent farm-water use, which is where most of our water use is besides environmental flows - I think that would provide a much better perspective than the one-gallon water bottle we buy in the supermarket:

The 1.3 billion gallons are equivalent to 4,000 acre-feet per year. Compare that with USGS estimates of total groundwater use in the Amargosa Valley: as low as 14,000 acre-feet and as high as 21,000 acre-feet per year recently. Indeed a big chunk of that basin's water. From an Amargosa Valley farmer's point of view about enough to water alfalfa crops on 800 acres (1+ square mile) area (also see the company's construction plans, p. 25). Not much perhaps by California standards, but a big chunk in the Amargosa Desert.

From a water consumption point of view, the dry-cooling alternative is much more attractive than the above cited wet-cooling technology: the total water use would be 400 acre-feet per year instead of 4,000, the equivalent of an 80 acre farm. Turns out, the two solar farms themselves take up about 4,000 acre-feet of public land (not previously farmed), generating approximately 500 MW of electricity (about half that of a nuclear power plant).

Another example cited in the article is the BrightSource Energy Ivanpah project in Southern California: for a 440 MW dry-cooled plant, the water use is 80 acre-feet (25 million gallons). This is another 80% reduction in water use over the similarly sized Amargosa plants under their better dry-cooling option! To put it in perspective relative to farm water use: 80 acre-feet would be enough water to irrigate a 10-15 acre alfalfa farm or a 30 acre vineyard in Southern California. The real important point here is not the "25 million gallons of water" but that there is already technology that provides huge improvements in water use for these alternative "green" energy sources.

For a yet better perspective, let's convert these numbers to gallons of water withdrawal per kWh generated . I will rely on my own experience here. My home's 2.5kW solar panels are designed to generate about 3,500 kWh of electricity a year (this is probably a low estimate - after four months, I am already on course to generating near 4,000 kWh per year). The 440 MW BrightSource Energy solar farm should therefore produce about 700+ million kWh per year. The water use would be 1 gallon for every 28 kWh produced.

Compare this to water withdrawals for electricity production from coal power plants (which produce 52% of the U.S. electricity supply): 25 gallons for every 1 kWh produced (check Sandia National Lab's "The Energy-Water Nexus" primer). In the NY Times article,Todd Woody quotes UC Berkeley's Daniel M. Kammen: "When we start getting 20, 30, or 40 percent of our power from renewables, water will be a key issue". I would counter: How could a 700-fold (!!!) decrease in water withdrawal per kWh make water a bigger issue than what it already is?

Lets put this in another perspective: according to "The Energy-Water Nexus" primer, the U.S. demand for new energy will be about 400,000 MW over the next 20 years. That is 1,000 new BrightSource Energy solar farm plants (80,000 acre-feet of water use). If we were to build these with power plants that use as much water as the BrightSource Energy solar farm and trade agricultural water in to meet the additional demand - that would be 30,000 acres of California farmland - or approximately two-thirds of the vineyard acreage in Napa Valley, California.

Sounds like a lot? Were we to meet this with coal power plants, and retired a water-equivalent amount of farmland, we would need to retire 21 million acres of irrigated farmland to save 56 million acre-feet of water - that is twice the total irrigated acreage in all of California or all of the irrigated lands in Arkansas, Texas, and California combined - representing one third of the total national irrigation water usage.

Despite the water use of solar power plants - with sound technology alternatives they seem far superior in their water footprint to standard power plants. Clearly, location and water source are central issues here, as the Amargosa and California water-energy discussions show. For a good discussion, see Mike Hightower and Suzanne Pierce's Nature article: "Some specific suggestions for reducing water usage by electric power generation include: using waste water, sea water or brackish groundwater for cooling and processing instead of freshwater; using cooling technologies that require less water or no water; switching to renewable energy technologies that do not need water for cooling — such as wind and solar electric; introducing technologies to condense evaporation from cooling towers and capture and reuse the water." And there is always my favorite: conservation. But let's be sure: to brand solar as a water guzzler ignores the real water use in much of our conventional power generation.

For a complete picture, we need to consider that not all water use in coal power plants is consumptive. Much of the water use in conventional power generation is simply for cooling while the water stays in the river. Here is a table courtesy of Mike Hightower from Sandia National Lab [from: Sandia National Lab Report SAND 2007-1349C):

Note that 1 gal for every 28 kWh in the case of the BrightSource solar plant is equivalent to 35 gal per MWh (the unit used in this table). A similar table can be found on p. 38 of a Report to Congress by this same group. Solar still comes out ahead! Check out Sandia National Lab's Energy-Water Nexus Website. And if you want to see, where solar is being build in the Southwest, check out SmartEnergyShow's solar map.

Water History

2009-08-20T18:02:00.001-07:00

The International Water History Association, through Springer, just began a new journal: "Water History". The journal promises to be a great resource for folks interested in all aspects of water and how humans' interactions with water have shaped our landscapes, our societal structures, and our history. The editorial in the inaugural issue explores the journal aspirations in more depth. Very readable material for everyone!

Having always had a bit of interest in history (my geography roots, also inherited from my father), I am looking forward - no: I am outright excited - to be browsing through this journal from time to time - for a physical hydrologist, this journal will provide great stories from the past to bring our science alive - for myself, for my classroom, and for my workshops. My first read will be Kate Berry's

" Fleeting fame and groundwater: isolation and water in Kings River Valley, Nevada".

Loosing Groundwater at the Grand Scale

2009-08-19T18:30:00.001-07:00

This week, an intriguing study, in which scientists used satellites to determine groundwater depletion at the continental scale, put the spotlight on groundwater withdrawals in India. [Original article in Nature (for those with access via their library), a review in the Washington Post and in the ScienceBlog]. Very timely article for Americans worried about dwindling groundwater resources in the High Plains Aquifer, in the arid Southwest, or in California. The article, by Matthew Rodell and others, reported that, over a six-year period, the average annual loss of groundwater across three states in northwestern India (not just a single small basin) was about 4 cm (1.6 inches) equivalent height of water or nearly 18 cubic kilometers per year across the 450,000 sq.km (170,000 sq.miles) region. At 12% specific yield (the proportion of the ground actually occupied by groundwater), this means an average annual decline of 0.33 m (1 foot) across that entire region. During the period of observation (2002-2008), the precipiation in Northwest India was reported to be about average.

What is interesting about this number is that this is not an untypical rate of long-term groundwater level decline in semi-arid/arid regions with irrigated agriculture or intensive urban groundwater use: water level declines on the order of 30 cm to over 1 meter per year. The North China Plain, a 140,000 sq.km region with both, high population (more than 110 million) and intensive irrigated agriculture (a lot of maize and winter wheat double cropping), lack of surface water and intensive groundwater exploitation have led to annual groundwater level declines exceeding 1m per year. In many overdrafted aquifers of the U.S., including the High Plains aquifer (about the same size at the area in India investigated, but with declining water levels more localized), the alluvial aquifer supplying the City of Tucson (0.5 - 1 m/yr), and some portions of the southern Central Valley aquifer system in California, we have seen similar rates of decline over the past 50-100 years. The result being that unconfined aquifer water levels that used to be within a few feet of the land surface are now 50 to 150 feet deep, and sometimes even more. During drought periods, water level declines can be much larger (check out the figure in my May 14 blog below).

The other part of this study that is noteworthy - because it confirms observations elsewhere and is an important characteristic of aquifers - is the observation of large year-to-year variations in groundwater storage. Compare their results, for example, to the figure in my May 14, 2009 blog: Year-to-year variations averaged across Northwestern India can be as high as 20 cm (equivalent water height), about as much as we saw in our Tule River Basin study in the southern San Joaquin Valley.

Increasing Water Productivity in Agriculture?

2009-08-19T17:24:00.000-07:00

Here is a very good article (and some food for thought) on agricultural water productivity from people who have looked at the water business in agriculture around the globe for some time. The article clarifies the key hydrological and irrigation engineering concepts around the politically hot topics "water use efficiency", "irrigation efficiency", and "water productivity" in agriculture. A very good read even for non-scientists. I am copying the abstract below.

One of the authors of this study is Pasquale Steduto, a UC Davis alumni, now head of the Water division at FAO in Rome. He recently visited the Davis campus and gave an overview on the state of water around the globe, which you can check out here.

The article has just been published in the journal "Agricultural Water Management"(Volume 96, Issue 11, November 2009, Pages 1517-1524).

Increasing productivity in irrigated agriculture: Agronomic constraints and hydrological realities

Chris Perry^a^,^,, Pasquale Steduto^b, Richard. G. Allen^c and Charles M. Burt^d

^aConsultant water resources economist, 17 Storey Court, St John's Wood Road, London NW8 8QX, United Kingdom
^bDivision of Land and Water, FAO, United Nations, viale delle Terme di Caracalla, 00153 Rome, Italy
^cDepartments of Civil Engineering and Biological and Agricultural Engineering, University of Idaho, Kimberly, ID, USA
^dIrrigation Training and Research Center, BioResource and Agricultural Engineering Department, California Polytechnic State University, San Luis Obispo, CA, USA

Abstract

Irrigation is widely criticised as a profligate and wasteful user of water, especially in watershort areas. Improvements to irrigation management are proposed as a way of increasing agricultural production and reducing the demand for water. The terminology for this debate is often flawed, failing to clarify the actual disposition of water used in irrigation into evaporation, transpiration, and return flows that may, depending on local conditions, be recoverable. Once the various flows are properly identified, the existing literature suggests that the scope for saving consumptive use of water through advanced irrigation technologies is often limited. Further, the interactions between evaporation and transpiration, and transpiration and crop yield are, once reasonable levels of agricultural practices are in place, largely linear—so that increases in yield are directly and linearly correlated with increases in the consumption of water. Opportunities to improve the performance of irrigation systems undoubtedly exist, but are increasingly difficult to achieve, and rarely of the magnitude suggested in popular debate.

Article Outline

1. Introduction
2. Water accounting
3. Transpiration and evaporation—definitions, interactions and typical relationships
4. Engineering options: how irrigation water is applied at project and farm level, and how this affects water use, consumption, and the demand for water
5. Crop production—how yield responds to water availability; how yield is affected by water stress; and how climate affects water demand and crop production
6. Conclusions
Acknowledgements
References

Regulating California's Groundwater?

2009-05-14T21:31:00.000-07:00

Felicity Barringer from the New York Times wrote an interesting story in yesterday's NYT entitled "Rising Calls to Regulate California Groundwater". It nicely highlights the widely varying opinions on just how much or little the state ought to look into the farmer's backyard to check on her/his groundwater usage.

I had the opportunity to chat with Felicity last week as he prepared the story. Of course there is so much research that goes into putting these together and only so much that goes into print (that's why we all have blogs...). Here, in brief, are some of my thoughts on the topic, many of which I shared with Felicity:

Agricultural water use is not equal to the sum of groundwater pumping and surface water delivery. Crop consumptive use (the actual water evaporated into the atmosphere from crops, trees, vines, etc.) is less - sometimes much less - than the water applied. What happens with the rest? It runs off into a river or - in most of California's agricultural regions - it recharges a groundwater basin. Putting a meter on a well does not "measure" the farms groundwater "use" as 10% to 50% of that may just percolate right back to the groundwater.

Then how should farm water use be measured instead? A few years back, CALFED convened an independent panel on Appropriate Measurement of Agricultural Water Use, which I had the honor to be part of. Our final report highlighted key options to go about measuring both surface water use and groundwater use in agricultural settings:

---Independent Panel Recommendation----

* Employ more precise methods to compute and report net groundwater usage to the State. [...] Accordingly, the Panel recommends that the State employ more precise methods—specifically, continuous regional characterization of groundwater volume to compute net usage using two methods simultaneously:
(1) development of detailed sub-basin hydrologic balances; and
(2) the water table/specific yield method (which requires measuring water levels rather than groundwater extraction).
This approach represents a substantial change from current practices. Footnote: Felicity's article mentions the Pavley bill (SB 122), which would be a big first step towards doing just that: monitor water levels throughout the state (It's a reincarnation of previous year's bills, all of which - including this one - have been championed by the Groundwater Resources Association).

* When water transfers involve groundwater substitution, the groundwater wells directly involved in the transfer require some form of continuous measurement,
monitoring and frequent reporting.

* This definition [of groundwater measurement] should in no way be considered to preclude or limit higher standards of groundwater measurement that may be deemed necessary by entities with legal jurisdiction over groundwater management, including local agencies or authorities, to meet site- or condition-specific needs.

* Crop Water Consumption Measurement: Measure using satellite-generated remote-sensing. Current approaches to measuring crop water consumption rely on indirect methods applied infrequently, a practice that means state estimates of crop consumption—a significant portion of California’s total water use—are not validated
and could include significant error. The Panel’s recommended approach—using satellite-generated remote sensing to measure crop consumption—is expected to
yield significantly better estimates than current practices. [...] and would have no direct impact on water users.

-------------------------------------------------

On this latter approach: my former grad student Alec Naugle and former postdoc Nels Ruud, a few years back, used a straight-forward water balance approach, based on monthly precipitation, monthly surface water deliveries to individual water/irrigation districts, monthly field-by-field crop consumptive use, and soil moisture tracking, to estimate monthly groundwater pumping for each of about 10,000 individual fields in southern Tulare County from 1970-2000. This approach may be as good or better as any well extraction metering approach to get a handle on groundwater usage. Detailed maps are available in our 2003 final report and the methodology and regional results with examples are published in a Journal of Hydroloy article (Ruud, N.C. et al., 2004) (see the bottom of our project page for these and related pubs). Our estimated field-by-field groundwater usage, aggregated to the district and regional scale, compared well with the water level fluctuations observed in that basin - confirming the importance of water level measurements as one of the cornerstones to understanding net groundwater usage.

David Maidment, Univ of Texas, told me on his visit to UC Davis today that around the same time our Water Panel convened, he was chairing a committee on the National Academy of Sciences that published "Estimating Water Use in the U.S.: A New Paradigm [..]". Chapter 5 of this report describes a "stratified random sampling" approach, a technical term for the kind of smart polling done in presidential elections, to estimate actual groundwater extraction. The approach was tested on the Arkansas database, containing 36,000 groundwater withdrawal points. The conclusion of the exercise was that "the single largest withdrawal points should be measured, and a random sample of 109 points (approximately 0.3 percent) should be selected from the remaining 36,052 groundwater withdrawal points. Hence, with groundwater withdrawals for irrigation, which account for over 80 percent of all withdrawal points in the state database, random sampling is sufficient for statewide water use estimation." (p. 94). In other words, a small - smartly selected - subsample of existing wells may be sufficient to get a good estimate of actual extraction. There are some caveats to doing this in the absence of the kind of database available in Arkansas, but far from everything needs to be measured to estimate groundwater withdrawals at the scale necessary to manage groundwater.

Overdraft, of course, has been one of the key topics that Felicity and I spoke about. Given the drought, which has led to recent drops in water levels, overdraft is popularly looked at as the imminent result of the state's lack of a rigorous groundwater permit system. Looking at well level records of past droughts, I have found that water level drops of 10 feet to more than 30 feet per drought year are not uncommon in the San Joaquin and Tulare Lake Basin. The repeated cycles of drought, during which groundwater is "overdrafted" and wet periods, during which groundwater levels recover can be nicely seen in the above-mentioned J. of Hydrology article. The below shows the regional groundwater storage starting from 1970.

[Note: this is the net change - in cm height of water - in water storage across the entire project area - about half of southern Tulare County on the valley floor. 30 cm is one acre-foot per acre. In terms of water levels, 3 cm net water storage change correspond approximately to one foot in water level change.]

Depending on which year you start and end your analysis, you may see "recovery" (e.g., 1977-1998), "no change" (1970-2000), or "overdraft" (1970-1995). Given that the large groundwater storage swings occur over the course of a decade; and given that it's only been 4 decades since we have the state and federal water projects in place, we often have simply not a long enough time series to establish that a basin is indeed in a period of "long-term net decline in water levels", which is a broad definition of overdraft. More importantly, a three- or five-year decline by itself does not establish "overdraft", it may just be part of good (intentional or not) groundwater management. This is not to say that there are basins with clear overdraft, only to demonstrate the difficulties and shortcomings in determining overdraft with relatively short time-series of water level measurements.

Groundwater regulation, fueled substantially by the last three years of drought, has been in the California news quite a bit ever since Cathryn Freeman from the CA Legislative Analyst's Office (LAO) suggested it in two reports last year, a water primer and a brief on groundwater management, and recently reiterated in "Water Rights: Issues and Perspectives": that the state "regulate" groundwater:

"However, successful implementation of this solution is hampered because groundwater use is generally not regulated or monitored at the state level (in contrast to surface water). In addition, local groundwater management does not take into
account statewide water needs. Finally, groundwater quality is not protected under state regulation as comprehensively as surface water quality. When contaminated, groundwater loses its potential to serve as a water supply source. Recommend Statewide Groundwater Rights and Quality Permitting System. For the reasons stated above, we recommend that the Legislature establish a state-administered water rights system for groundwater." (p.69 of the LAO water primer).

I have some open questions on the use of an outright permit system for groundwater:
* as California may be the last state without a groundwater permit system, is it really doing any worse with respect to groundwater management than the other 49 states?
* all of the States overlying the Ogallala / High Plains Aquifer regulate groundwater - has that stopped overdraft from that aquifer system?
* by which measure do we judge "good" and "bad" groundwater management? The popular answer would probably be: whether or not there is overdraft. But when exactly is a basin in overdraft - see above image and discussion?
* how much groundwater would be allocated to permits? There are examples from adjudicated basins - typically based on "safe yield" estimates. How would that be determined under conditions of climate change?
* Catherine, in her LAO report, laments the shortcomings of the surface water rights system, which IS based on permits. Why should we apply the same system to groundwater? Management is still left to local agencies. My hunch is that the existing, locally controlled system provides much more flexibility as is, as long as the "bottom of the barrel" (lowest allowable water level) is defined clearly and consequences of exceeding that depth are set out clearly. The idea of "permits" seems simple enough to grasp as a solution, but is it really effective in managing groundwater? In and by itself, it doesn't do anything to manage groundwater, especially since groundwater - unlike surface water - must really considered to be a bank/storage reservoir, rather than an incidental stream of water that is either there or not there at any given time, to be distributed and used at that time.

Well, well, we will certainly talk a lot more about this at the upcoming Biennial Groundwater Conference, 6-7 October 2009, in Sacramento!

Ah, and before I forget: Felicity's colleague Alicia inquired about comparing state groundwater usage in the U.S as part of Felicity's story. This is what I wrote her back:

The USGS Circular 1268 would be the best resource for making any
state-to-state comparisons that I know of.

On this following page, you find text that says "California accounted
for 18 percent of total groundwater withdrawals." [note that the USGS
is now changing the spelling of 'ground-water' to the much more common
spelling 'groundwater']

http://pubs.usgs.gov/circ/2004/circ1268/htdocs/text-total.html

A map is shown in the lower left of their Figure 2:

http://pubs.usgs.gov/circ/2004/circ1268/htdocs/figure02.html

The corresponding numbers are tabulated by state in their Table 1
under "Ground Water"-"Fresh" (2nd column from the left):

http://pubs.usgs.gov/circ/2004/circ1268/htdocs/table01.html

While these numbers are for the Year 2000, newer numbers would not
necessarily add better or more updated information. Groundwater
pumping in states like Texas and California varies quite dramatically
depending on whether we have a wet year, a normal year, or a very dry
year. In California, groundwater pumping varies from approximately 10
million acre-feet per year in wet years to nearly 20 million acre-feet
per year in dry years. See, for example, the California Water Plan
Update 2005, Figure 1-10, lower panel, in the following pdf file:

http://www.waterplan.water.ca.gov/docs/cwpu2005/vol3/v3ch01.pdf

Groundwater pumping is shown in dark burgundy or purple color for a
wet (1998), normal (2000), and dry (2001) year. That means, in any
year, groundwater contributes from approximately one-third to well
over one-half of the total fresh water supply for agriculture and
urban uses in California.

Global Groundwater Recharge Map & Water Use

2009-04-26T10:24:00.001-07:00

Ever wondered how much water percolates into the ground? Petra Doell et al., a few years back, published a global map of estimated groundwater recharge, which they recently updated and extensively discussed i n a public journal article that includes beautiful color maps (I admit - I always liked looking at good maps). An interactive version of the recharge map is available now at the WHYMAP (world-wide hydrogeological assessment and mapping program).

Global groundwater recharge is nearly 13 thousand cubic kilometers (a little more than 10 thousand million acre-feet) or about one-third of all renewable water resources. On average that is a little over 2000 cubic meters of renewable groundwater per capita per year, but may be as little as 10 cubic meters in some arid countries (for comparison: FAO estimates that at least 1700 cubic meters of water are needed annually per capita to meet living standards). Not surprisingly, the least available recharge or renewable groundwater (per capita) is in arid and semi-arid regions - much of China, India, Pakistan, Middle East, Northern Africa, and the U.S. Southwest/Mexico. Notably - these are also regions, where much of the global groundwater extraction occurs (because renewable surface water resources are equally scarce there).

Speaking of groundwater extraction: The reason I stumbled across this today is a wonderful book called "The Agricultural Groundwater Revolution" edited by Mark Giordano and Karen Villholth. It provides a comprehensive overview of groundwater use, management, and policy in agricultural regions around the world. I can highly recommend the reading! Among many other things, the book provides an insight into groundwater pumping in many regions.

I needed to familiarize myself with some of these numbers and how they stack up against those that I know (for example, the California water budget). Here are some big numbers I came up with that may serve otheres as comparison as well (I apologize for the poor table format. Sources I used: USGS Circular 1298 for California and the U.S., Pacific Institute's World Water Report for world total, which lumps domestic and public water supply into a single category):

Note: GW refers to groundwater, SW refers to surface water; "industrial" also includes water use in mining and energy production. The above numbers are freshwater supplies only.

The Spiritual Power of Groundwater!

2009-04-06T22:50:00.000-07:00

Springs and seeps and sinks. I always am impressed by water simply appearing out of no-where or disappearing into no-where. Well, not exactly no-where - it is out of the ground or back into the ground. An ephemeral realization of that which is invisibly beneath - groundwater. I grew up in a humid temperate climate, so a spring was an every day thing, although large springs have always been particularly impressive. It wasn't until I moved to the desert Southwest that I first experienced the opposite - a stream disappearing into the underground of a sandy streambed at full speed (the Canada del Oro as it leaves the Catalina Mountains north of Tucson, AZ). My video is posted here:

This video is from one of the most gorgeous places on this planet, the Lost Coast in Northern California. Behind large beach sand dunes, a mountain stream has filled a small basin to form a pond. The sand dune that forms the beach is permeable enough to keep the pond from overflowing. Instead, the water filters through the sand dune and reappears on the other side as a spring - but the stream only goes so far before it again disappears into the sand. Quite impressive.

More than anything else, it is visual poetry.

I apologize for the noise - it was a windy day and my commentary was simply blown over. But the imagery speaks for itself.

Farm Nitrogen Balance for CA

2009-04-05T22:42:00.001-07:00

I am working on an article for the upcoming Nitrate issue of Southwest Hydrology. One of the big picture numbers that I have been following is the statewide farm nitrogen balance in California. Here is the back-of-the-envelope computation that I am coming up with - somebody correct me if I am way wrong:

The average farm acreage with fertilizer use (1980-1984) was 6.066 million acres with an average of 595,000 tons of N fertilizer sold (Norman, Hargett, Berry, Fertilizer Summary Data, National Fertilizer Development Center, TVA, Alabama), which amounts to 197 lbs/acre. A similar number was reported by Jeffrey Swanson and Dale Dahl (on p.24): 217 lbs/acre. The crop acreage with fertilizer use in the 2007 Ag Census was somewhat higher(6.728 million acres), while fertilizer use has leveled off since the 1980s. For 2007, nitrogen farm use was 740,000 tons (CDFA). Total irrigated crop acreage in the 2007 Ag Census was 8 million acres, of which 740,000 acres are pasture and other (non-crop) land.

The fertilizer use efficiency in California is reportedly on the order of 44% (my 2002 notes refer to "DANR Bulletin 1887, Table 9"). Assuming that it has improved to roughly 50%, this leaves over 100 lbs N/acre for leaching. If 25% of that goes to volatilization and denitrification, average nitrogen fertilizer leaching on California farmland amounts to something on the order of 75 lbs N/acre/yr. At an average recharge rate (under irrigation) of 1 acre-foot/acre/yr, this is nearly 30 mg/L of nitrate-nitrogen in recharge. This estimate is somewhat higher than what has been measured - on average - in some agricultural groundwater monitoring networks.

Dairy cows. They are the biggest animal industry in the state. Some 1.8 million milking cows as of last year, producing 41.2 billion lbs of milk (yes, I drink a lot of it - and do it my share of cheese), which contains 3.15% protein or 100,000 tons of nitrogen. The amount of nitrogen excreted by a milking cow is approximately three times more than that going to milk. In other words, a milking cow has a 25% nitrogen efficiency - 75% of the N consumed goes out the back end.

Hence, adult milking cows (including non-lactating or dry cows) produce about 300,000 tons of nitrogen. Then there is about as many support cattle (calves, heifers) as there are milking cows, which produce another 100,000 tons of nitrogen - a total of 400,000 tons of manure nitrogen.

We obtain the same number based on average estimated excreted nitrogen: about 1 lbs/day for a milking cow (300 days per year), 0.45 lbs/day for non-lactating adult cows (65 days per year), and the average for support stock is about 0.33 lbs/day. At 1.8 million adult cows and 1.8 million support cattle, this also adds to 400,000 tons of N excreted.

In a recent UC report, we estimated that 20%-40% of the N volatilizes in the production area (flush lanes, dry lots, lagoons). Hence, 240,000 tons manure N are applied to field crops. The same report estimated that another 25% either volatilizes or denitrifies after application to field forage crops. That leaves 180,000 tons of manure N for plant uptake or leaching to groundwater (most dairies are located on relatively flat land and must minimize runoff losses).

The 2007 Ag Census reports that 645,000 acres of farmland are treated with manure. At 180,000 tons manure N applied, that is 750 lbs N/acre/year. A double-crop of summer corn and winter grain will take up about 400 - 450 lbs N/acre/year. Which - on manured dairy forage crops - leaves at least 300 lbs N/acre/year for leaching to groundwater (not including any additional fertilizer). In an acre-foot of recharge that is more than 100 mg/L nitrate-nitrogen. This is consistent with our groundwater monitoring data in Merced and Stanislaus County, where we measured an average of 64 mg/L of nitrate-nitrogen under dairy forage crops in highly vulnerable groundwater conditions and with average recharge rates closer to 2 acre-feet/acre. We are seeing much lower nitrate-nitrogen concentrations (around 20 mg/L nitrate-N) in the upper-most groundwater under dairies with much less vulnerable conditions in Tulare and Kings County - groundwater levels are nearly 100 feet below ground surface and manure is spread over larger acreages (relative to the number of cows).

(Note that 27 lbs N in 1 acre-foot of water equals 10 mg/L nitrate-N).

Nitrogen Fertilizer Centennial

2009-04-05T16:00:00.000-07:00

One hundred years of nitrogen fertilizer - and what an incredible green revolution it has been! The article below from Scientific American highlights some of the current issues with global fertilizer use in the context of biofuels. Funny that the article should leave out any mention of groundwater. Nitrate is only the most common groundwater contaminant worldwide next to salt. In California nearly 10% of water supply wells are at levels above the maximum contaminant level (MCL) of 45 mg/L (Nitrate) or 10 mg/L (Nitrate-Nitrogen). In a recent survey of domestic wells in Tulare County, California, over 40% of domestic wells exceeded the nitrate MCL. The county is one of the largest agricultural producers in the country with large acreages of citrus, vineyards, tree crops, and forage crops. It is also the largest dairy producer in the United States. Dr. Erik Ekdahl from the California SWRCB recently gave an illustrative presentation with maps showing 1980-2007 groundwater nitrate trends in California based on results from nearly 10,000 wells. If you are a GRA member, you can download his presentation from their website.

the below is posted from:
http://www.sciam.com/article.cfm?id=nitrogen-fertilizer-anniversary

March 20, 2009

Nitrogen Fertilizer: Agricultural Breakthrough--And Environmental Bane

A new report citing drawbacks of the corn ethanol craze casts a pall over the centennial of a Nobel Prize-winning discovery that transformed global food production

By Sarah Simpson

One hundred years ago this month, a laboratory experiment at the University of Karlsruhe in Germany set the stage for the Green Revolution. Chemist Fritz Haber placed a sheet of osmium in a steel chamber, pumped in a mix of nitrogen and hydrogen gases, and cranked up the heat and pressure. Then, out flowed ammonia, the elusive raw material for producing synthetic fertilizer. It was the eureka moment scientists had been pursuing for a decade: Haber managed to create the necessary conditions to transform nitrogen gas, abundant in the atmosphere but useless for life, into a digestible form. The work would earn Haber the 1918 Nobel Prize in Chemistry. (Many protested the award because Haber had been instrumental in developing and deploying chlorine gas for Germany during World War I.)

Once implemented on an industrial scale, ammonia synthesis enabled the widespread fertilization of croplands for decades hence. As a direct result, the world's population skyrocketed from 1.6 billion to six billion during the 20th century. But Haber's nourishing discovery has a dark side he probably never imagined. The boom of fertilizer, long injudiciously applied, has come at a high price for the environment.

And now, according to a new report to be released later this month by the Scientific Committee on Problems of the Environment (SCOPE) of the International Council for Science, society's aspiration to use biofuels to kick its oil addiction could backfire. By intensifying nitrogen pollution, a business-as-usual approach to biofuels production could exacerbate global warming, food security threats and human respiratory ailments in addition to familiar ecological problems. Scientists have long known that the reactive nitrogen in fertilizers leaching from agricultural fields (as well as those smaller amounts exiting tailpipes and smokestacks) wreak havoc as they cascade through the air and rivers. Rogue nutrients often spur harmful algal blooms as they flow into the ocean, and hundreds of estuaries around the world suffer from so-called seasonal dead zones as a result. "We're getting to the point where dead zones will be continuous bands around the continents," warns marine ecologist Jeremy Jackson of Scripps Institution of Oceanography in La Jolla, Calif.

Fixing the nitrogen problem is at the heart of Jackson's call to make the Green Revolution truly green, a sentiment echoed by scientists around the world. A primary culprit: so-called first-generation fuels, which are based largely on fermentation of cane and corn sugars.

"The production of ethanol from corn in the U.S. is a disaster in terms of fertilizer flowing down the Mississippi River," says Cornell University environmental biologist Robert Howarth, chair of the International SCOPE Biofuels Project. The U.S. Energy Independence and Security Act of 2007, passed with strong bipartisan support, set a goal of producing 54 billion liters (14.3 billion gallons) of ethanol from corn by 2022. But new research outlined in the SCOPE report indicates that, without a change of practice, meeting that goal could increase the nitrogen flux in the Mississippi by 37 percent. That pits ethanol production overwhelmingly against another national goal: reducing nitrogen flux in the same river by at least 40 percent to reduce the size of the dead zone in northern Gulf of Mexico.

Corn is a troublesome biofuel source, particularly from a nitrogen standpoint, Howarth says. Typical corn-growing practice is to apply high doses of fertilizer, with substantial losses to the surrounding environment. Corn has very shallow roots compared to most crops and so can use nitrogen only in the top one to two inches (0.4 to 0.8 centimeters) of the soil. Moreover, it only takes up nitrogen and other nutrients for 60 days out of the year. Other crops such as soybean and wheat have deeper roots that are active longer. But the rising price of corn has encouraged farmers to grow more of this "nitrogen leaky" grain. Land set aside for conservation purposes as well as some active soybean and wheat fields are being converted back to active corn cultivation.

Still, this growth in corn production cannot hope to enable the world to reach its ethanol production goals, the report says. The U.S., for example, put 24 percent of its 2007 corn harvest into ethanol, yet that generous contribution amounted to only 1.3 percent of the nation's use of liquid fuels. Based on this and other early findings, the SCOPE report projects that substituting 10 percent of the liquid fossil fuels used for transportation with biofuels could require a third of the world's arable land, causing trouble not only with nitrogen pollution but also food security.

Current biofuel targets impart other major problems for global warming and human health that Howarth says scientists have "long underestimated." Fertilizers release significant quantities of nitrous oxide, a greenhouse gas with 300 times the heat-trapping capacity of carbon dioxide (CO2). A 2007 analysis by Nobel laureate Paul Crutzen of the Max Planck Institute for Chemistry in Mainz, Germany, and his colleagues suggests that for most current biofuel crops, corn included, any CO2 savings will be wiped out by higher emissions of nitrous oxide and nitrogen oxide. The latter destroys so-called “good” ozone, which shelters life from damaging ultraviolet radiation; it also fuels production of ground level ozone, the main constituent in smog that is widely known to exacerbate human respiratory ailments. According to the U.S. Environmental Protection Agency, millions of Americans live in areas that exceed the national standards for ozone exposure.

Even as researchers sound the alarm on biofuels, they suggest promising solutions. On the horizon is cellulosic ethanol, sometimes dubbed "grassoline". The wood or woody grasses that are the feedstocks for these so-called second-generation biofuels can be grown on marginal lands (thereby not competing for space with food crops) and need much less fertilizer, according to chemical engineer George Huber of the University of Massachusetts Amherst. A mature cellulosic biofuel industry will be able to compete with oil at around $50 per barrel and deliver fuel to the pump at about $2 per gallon, say Huber and his Michigan State University colleague Bruce Dale.

But that vision is still several years off, Howarth points out. Meanwhile, the SCOPE report suggests that even grassoline may not be the best use of biomass: "The world would be better off using the cellulose directly for combustion," Howarth says. "If you try to use biomass in a stationary way, it's much more efficient." Direct combustion of switchgrass for heat and electricity can provide 2.6-fold more energy than converting the same source to ethanol—and 9-fold more energy than producing ethanol from corn. The proof is out there: 35 percent of homes and commercial buildings in Sweden are heated by combustion of biomass, mostly willows grown on nearby plantations.

Biofuels are a hot topic right now, but the litany of issues surrounding fertilizers and nitrogen pollution are far more complex. Foremost among the challenges is the need to use more fertilizer to combat hunger in many parts of the world, points out ecologist Alan Townsend of the University of Colorado at Boulder. Townsend, like Howarth, has spent much of the past 15 years analyzing the human perturbations to the global nitrogen cycle. More fertilizer is badly needed to help feed burgeoning populations in much of the developing world, and yet mistakes of the West are being repeated elsewhere. A study published in February suggests that China could cut its fertilizer use by a third without reducing crop yield. Pursuit of meat-intensive diets, which requires massive production of fertilized crops to feed animals, is another problem Townsend and Howarth point out.

Despite their dire warnings, neither scientist is a pessimist. Haber's discovery has been a miracle for a century, Howarth says. We just need to be smarter about how we apply it.

More with Less? Sure, but...

2008-11-04T10:00:00.000-08:00

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