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.