Category Archives: Irrigation!

In other years, black or Asian kids have gotten thirsty.

I took my first hard look at the cover for the draft Water Plan and I laughed and laughed and laughed. The images are standard, kid drinking, sprinklers on ag*, governance, nature, clouds. Whatever. Then! The ONE picture of the Delta is of a levee break (Franks Tract?). Yep. That’s the one thing you need to know about the Delta. Levees break. Guess we need a Peripheral Canal, then.







*Solid set, not hand more. You see how the throw area overlaps? That means all those sprinklers stay there and water the field for the whole season. Solid set. Hand move sprinklers are at much wider intervals. After they irrigate an area, the line gets broken down and moved to the outside of its throw pattern. (The ones in that picture are wheellines, but the thing I’m trying to show is the far apart spacing.) That’s how you tell solid set and hand move sprinklers apart from a distance. The spacing.

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I will never explain the unit “acre-foot” on this blog.

I’ve been slow to finish up my review of the Pacific Institute report, because that will mean that I have to get into the concepts of field and basin efficiency and I dread that.    I don’t mean to be a tease; I know how badly you’ve been craving more of this series.  I’ll put some peripheral thoughts here,  so we can have a clean discussion of field and basin efficiency and the core conclusion of the Pacific Institute report without them buzzing around and plaguing us.

A thought:

I agreed with the technical critiques in the irrigation professors’ report, which isn’t too surprising, since one of them trained me.  If you have any technical questions about anything in those reports, I’d be happy to take my best shot at answering it.  As much as those critiques cast doubt on whether the Pacific Institute report is identifying real potential for water savings, I’m also a doubter.

Another thought:

I said that I’d critique the Ag Water Management Council’s report.  Here goes.  This is self-reporting by a self-selected group of the most progressive ag water districts.  I don’t think the claims are very impressive; there’s a lot of hedging about how far along the districts are in adopting Efficient Water Management Practices.  That said, these leading districts are alert to the practices and implementing them at some rate unspecified by the report.  I don’t take this report as proof that ag is doing everything it can.  It is more like the best likely spin you could put on ag’s water use practices.  Also, man.  Love the pictures. 

Yet more thought:

For your sense of scale, here are some recent rough numbers.

3.5 million acre-feet/year – the Pacific Institute report thinks this is the amount ag could yield without hurting, or maybe even while doing better.

31.5 million acre-feet/year – this is roughly how much ag applies overall.  Am I really doubtful that irrigated ag could give up 10% of its applied water without hurting?  Are they really so tight that there isn’t 10% slack in the system?  Yeah, I really am doubtful, and I’ll tell you why when I tackle the field and basin efficiency talk.  But OH LOOK!

6 million acre-feet/year – this is how much warmer winters will cost CA in snow storage of water by mid-century.  That’s twice the amount we’re wrangling about in the Pacific Institute report, so as much as the Pacific Institute report seemed to be making bold claims, this should be twice as dramatic.

I’ll give you three more numbers that I find really handy.

10 million acres – the rounded-up area of irrigated ag in California.  It is closer to 9 million acres these days, but 10 million acres is easier to use.

California is about 100 million acres. 

As a very, very rough estimate, one irrigated acre uses about three acre-feet of irrigation water a year.  (This goes neatly with the 10 million acres and 31.5 million acre-feet/year.)

These are the numbers I use to get a gut sense of things*, decide whether a claim is big or little or ridiculous.  You may use them too.





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Filed under Basic stuff, Irrigation!

More on the Pacific Institute report

The Pacific Institute report writes in the “Efficient Irrigation Technology” section that considerable water could be saved if growers used drip or sprinkler systems instead of flood or furrow. This is a reasonable sounding concept that falls apart when you get to specifics. To get the kind of savings the Pacific Institute estimates (0.6 million acrefeet), you’d have to convert a whole lot of acreage to drip or sprinkler. So much acreage, in fact, that much of it would have to be field crops. In their report critiquing the Pacific Institute, a few irrigation professors wrote this paragraph, which I loved because it shows why the details matter so much:

The flood to sprinkler conversion on field crops would need to occur on alfalfa, pasture, cotton, or corn. Cotton acreage is now less than 300,000 acres (not the 886,000 acres used in the report), and sugar beet acreage in the Valley will disappear soon. Safflower is most often minimally irrigated and rice is not a candidate for sprinkler irrigation. Corn is problematic to sprinkler irrigate due to its height, which would require that center pivot or linear move systems be installed. While alfalfa and corn prices have been strong lately, the cost of conversion from flood to sprinkler irrigation is considerable and may not be justified by field crop growing economics. (pg 11)

This is such a good summary of why it gets very hard to talk about ag and why the sides of the debate tend to harden. I mean, it sounds right and obvious, that field crops should change from flood irrigation methods to sprinklers or drip irrigation methods. Except that as you discuss each specific field crop, each one doesn’t make sense. What cotton? What sugar beets? Safflower? Safflower is underirrigated now; why would you underirrigate it with expensive sprinklers? Corn is too tall for ground-based sprinklers and center pivot sprinklers don’t work well on California soils. Wheat is a winter crop, rainfed. Rice stands in a shallow pond you couldn’t fill with sprinklers. Alfalfa maybe, although you’ve got your tractor in there ten times a year to cut alfalfa, which could be hard on solid set sprinklers and no good for driplines. The nice thing about alfalfa is that amazing tap root, the one that makes it possible to let the plant go dormant in drought years, and that should be encouraged by really deep watering.

So here’s where the mutual exasperation comes in again. Enviros and urban-types say “Look, we know that if you switch to sprinklers you save water. This is known, and the need for water is urgent.” Ag answers curtly, because it is tired of repeating long explanations, “Whatever. That won’t work.” Enviros think growers are digging in because they have lots of water rights and are politically powerful and change-resistant. Growers wish enviros would stop insisting they make expensive nonsensical technology changes without demonstrating benefit in their real-life circumstances. This is a pretty big gap, between the plausible general principle of the enviros/urbanites and all the many, many constraints and specifics of ag. You can see how someone could get real vested in one or the other. It doesn’t help that ag’s objections look exactly like self-interest and that it is easy to point to historical poor practices. Or that enviros seem to want growers to go to a whole lot of expense and hassle so that they’ll have the privilege of forfeiting some water.

How will this be bridged, so that growers will make the worthwhile technology switches and enviros trust that the remaining systems are using water appropriately? Economists would say that pricing water without subsidies or protections would solve all that, and I agree that it would go a long way. Besides, no one would have to talk or trust or convince or agree on anything and god knows we hate interacting with people who are different from us. So there’s that. The other two choices are that enviros learn more about ag, enough to shake some of their certainties about how wasteful ag water use is. Or that growers change their systems because of other pressures, like drought or rising energy costs if they pump groundwater. I suppose it is possible that with enough mutual education and discussion, the sides could make careful compromises based on mutually established facts. But that isn’t the outcome I expect.


Filed under Irrigation!

I didn’t like the crop-shifting section.

The weakest section of the Pacific Institute report is the section on crop shifting. They wrote that shifting from low value field crops* that use more water to higher value row crops** that use less water could save 0.6 million acre-feet of water. I wish they hadn’t published that without much more data. Here’s why:

The issue that bothered economists didn’t bother me:
1. The Pacific Institute explicitly states that they base their model off gross values for the crops they put in their model. They admit that the net amounts may differ, because crops that fetch a lot of money at market may also require expensive inputs. That is something of a crucial point for growers. The economists get all hot and bothered and assert that if the net amounts for row crops were higher now, growers would have shifted already. I don’t think that is self-evident. I don’t believe that growers behave like the rational economic model. I think some are traditionalists, some may choose a crop out of familiarity, or because they accept lower profit for lower risk, or because they don’t know about all markets for all crops or because of local custom. So I think two things. The Pacific Institute model would be vastly better for using net values and it may be true that growers could make more money shifting from field crops to row crops.

Something else bothered me:

Unfortunately, the Pacific Institute didn’t show their model output telling us how many acres of what field crops would change to row crops. Without knowing each field crop and row crop, it is impossible to evaluate that section. For example, did they say that a few thousand acres of rice would change to peaches? Because that won’t work. Rice is grown up in big clay ponds up in the north Sac Valley. You can’t grow other things on that soil. You could get rid of a few thousand acres of rice, but you aren’t shifting to anything. Are they shifting out of alfalfa into broccoli? Alfalfa has had some extremely good years recently with all the new dairies in Kern County and broccoli processors are shutting their doors. Basically, anyone who keeps current with ag wants to know exactly what acres would change to what, and they didn’t tell us. No one current in ag believes a blanket assertion that whole sectors of ag are worth more than other sectors. There are far too many counterexamples and I don’t know if their model included those.

The irrigation professors critiqued this section by saying that they don’t observe year-to-year expansion in the row crop market, from which they conclude that growers are currently providing about all the vegetables the market wants. Switching to row crops might save water, but this isn’t a strategy based on responding to an extrinsic demand for row crops. (pg 9)

These complaints make it hard to take the crop-shifting section of the Pacific Institute report seriously.  I would love to see a version of this section using net values for crops and showing exactly which acreage would change.  But even with that information, I have a different, abstract objection to the whole concept of switching to higher value crops.




* Pasture and grains, mostly.
**Row crops are also called truck crops and are basically vegetables.

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I like to start by namecalling.

I must say, the Pacific Institute has balls of steel. They do what everyone else is scared to do: they predict how much water could be saved by changing how agriculture uses water. They give estimates, say that efficiency measures could save 3.4 million acrefeet. This is important. Now we know that the Pacific Institute is talking about more water than new dams would yield. Even more audacious, the Pacific Institute says that agriculture can save a couple reservoirs worth of water just by using more sophisticated irrigation methods and crop shifting. It can still be ag! Better ag! It can be even better ag, and we can have another 3.4 million acrefeet of water!

There’s a reason everyone else is scared to do this. If you ask ag water experts how much water can be saved (or how much is wasted, the same question), the answer is a lot of hemming and hawing, until they collapse into “it’s complicated.” This makes everyone outside of ag crazy. How complicated can it be? Tell me how much your crop needs and tell me how much you put on. My brain tells me the difference is the amount you wasted. The ag expert says no, it isn’t like that. We don’t know very precisely how much water the crop needs. It changes! It changes with the weather and time of year and stage of growth of the plant and what you want the crop to be like and what you want next year’s crop to be like. But, if you insist, we can make a rough guess. You know what else we don’t know? How much water we put on! Hah! Take that, Mr. Fancy Subtractor! OK, there has been a lot of improvement here too and a lot of fields are measured now. If they exist, those measurements are probably good within ten or fifteen percent (pg 8). Now you’re subtracting a rough amount from a rough amount, and the range is pretty big, maybe twenty or thirty percent of your totals. In fact, that range is just about the swing between inefficient water use and efficient water use.

That’s OK, say people who are determined to chase this down. We’ve worked in complicated systems before. Everyone thinks their system is complicated. Tell me, is there anywhere else the wasted water could have gone. Yes! Three places. Two of them are invisible! It could go into the air, through the plant or just off the ground, both of which are hard to measure! It could go underground, which you can’t see and lags by days, months or years and you need permission to measure, which you probably can’t get, and is different in the next soil lens over! It might also run off the end of my field. In that case, it might go to the next grower, who also irrigates his crops with it. Or it goes into a drainage canal, which is the last pitiful remnant of habitat left in the county. Or it goes back to a river, hot and full of pesticides. That might happen three or four times. So tell me, Mr. How Hard Can This Be, is it wasted? Remember, whatever you calculate for this field can’t be extrapolated to another crop type on a different soil type or different location in the region.

The problem is genuinely difficult and most people retreat about now. But the Pacific Institute is not afraid. They made rough guesses, well qualified, and give enough of their methods and calculations to be critiqued. Like all sensible modelers, they aren’t vested in any precise output of their model, but think it offers useful ballpark information. This is entirely respectable and their report just radically stretched the boundaries of the conversation about ag water use in the direction of efficiency and conservation. This is great. Sadly, I find the critiques of the model to be pretty persuasive. I think their rough guesses are too broad. I do not think 3.4 million acrefeet of water can be saved in the ag sector without substantially shrinking California ag.


Filed under Irrigation!

Lay of the land.

Couple months ago, the Pacific Institute put out a report, one in a series laying out a vision for California in 2030. Their overarching premise is that we have enough developed water sloshing around the state to get us through 2030, if we stop wasting it. They put out a volume on urban water use, but urban water conservation bores me to tears*, so I didn’t read it. They followed that with a report on the agricultural water use side. Since every last detail of irrigation is inherently fascinating, I read it breathlessly. They assert that agriculture can not only use substantially less water, but would profit by doing so.

Reaction to the report was mixed. It attracted a lot of attention, and in general people take what the Pacific Institute has to say pretty seriously. Some people liked it a lot. Others didn’t.

Enviros tended to like it because they see agriculture as the only potential source for the amount of water it would take to restore our rivers and the Delta. So much the better if agriculture can withstand the loss of that water and even thrive. Also, the Pacific Institute is talking big numbers, 3.5 MAF of water. That’s more than the size of the only proposed new dams that are real possibilities. We won’t need those dams if we can get that water from agriculture!

Ag didn’t like it, predictably. They don’t like being told they aren’t doing a good job at the livelihood that is also their identity. They especially don’t like being told that they aren’t doing a good job based on an outdated but widespread perception of their practices. They don’t like the implicit threat that the outside world is coming for the water they’ve always used. They (possibly mistakenly) see new dams as the only way of continuing their way of life, so they don’t like reports that suggest that dams aren’t necessary.

I’m sure you remember the sensational swirl of editorials, and how you yearned for someone to go through the report section by section and discuss each piece. You were hoping someone would look at it side by side a critique of the report issued by four irrigation professors. My heart heard your heart, dear reader. That’s what we’ll do this week.

*Here. I can tell you what it said. Meter water use and bill by volume. Fix leaks, big and little. Replace appliances. Switch out lawns and collect stormwater. That’s all good stuff, but just typing that bored me. I know you don’t come here to read boring things, so we won’t be talking about urban water conservation much here.

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Filed under Drought, Irrigation!