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<br />Comments to SWSI, November 3,2003, by John Wiener
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<br />supported management changes for decades, but there is an important gap between the theory
<br />and the practice. Note also that since 80 percent or more consumptive use of Western water is
<br />by agriculture, as often noted it would only take a fraction of that to be a significant increase in
<br />urban supply. One of the goals of taking this seriously is learn how a few percent here and there
<br />from many farms could be aggregated effectively to make that supply, without creating sudden
<br />and injurious changes in conditions dependent on the status quo.
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<br />Step 1 of The Irrigation Efficiency Problem: Simplest possible case.
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<br />Consider 100 acres being irrigated with 100 units of water. The technique is furrow irrigation with
<br />open ditch and the return flow from the diversion and application of 100 units of water is 50 units
<br />(50% efficiency of use, or "field efficiency".) The Arkansas River Water Bank Pilot Program
<br />(WBPP) allows transfer only of stored water, so the example will start with that.
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<br />Suppose for simplicity that this field is getting 75 units of direct flow, and 25 units of stored water.
<br />The 25 are eligible for the WBPP. Because the return flow has been established for this purpose
<br />to be 50 percent, by the State Engineer, 12.5 units can be transferred "away", and 12.5 are
<br />administered to maintain the pattern of volume and timing of return flow. The 75 units of direct
<br />flow can be applied to 75 acres, in the same way as before, and there will be 37.5 units
<br />consumptively used, and 37.5 will be return flow.
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<br />So far: the farmer has presumably received money from transfer of 12.5, and return flow is still
<br />50. (For simplicity, please overlook the internal workings of ditch and canal companies right now.)
<br />This is least controversial if the acreage irrigated is reduced; "dry-up" of 25 acres is required. So
<br />far, in the Arkansas, one of the objections to the WBPP is that there is no funding for enforcement
<br />of "dry-up", and some farmers think this is the only fair way to operate the program. The statute
<br />establishing the pilot program does no require dry-up, but many leading farmers think it should.
<br />Without the requirement, the farmer could spread the remaining 75 units of water on the 100 units
<br />of land, and the return flow would be less than it "should" be, since more of the 75 units of water
<br />would evaporate or be consumed by the crop. The farmer's efficiency of use would be greater,
<br />but the downstream would lose water.
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<br />"Dry-up", the requirement of non-use of a proportional area of farm land, is the simplest way to
<br />assure that there is no increase in consumptive use. Unfortunately, requiring dry-up requires
<br />losing all production from 25 acres, losing or affecting some soil fertility characteristics, affecting
<br />use or demand for farm labor, and affecting weed control and erosion. Also, the 75 acres is not
<br />giving a higher yield, since management has not changed. The local economy is affected by
<br />reduced production.
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<br />Enforcement of dry-up also requires some effort by someone at some expense; can this be
<br />avoided? Many farmers feel that self-enforcement is not credible, given the strength of incentives
<br />to cheat.
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<br />A note: jf the land taken out of production was not yielding enough to at least "break even", it
<br />would be taken out in any case. So, without some other change, this reduces production. If the
<br />dry-up requirement is imposed, it would seem also to require taking fairly observable areas out of
<br />production, in contiguous pieces. If the amount taken out of production was in corner areas not
<br />reached by center pivots, this might have less negative effect than jf the dry-up area was more
<br />arbitrarily specified. But if the lowest-yielding soils were taken out of production, the shapes and
<br />pieces of land might reflect contours or underlying soils and subsoils. That might be most
<br />beneficial for the farmer, but hardest to monitor. (You would also see farmers designating some
<br />of their best producing soils, especially alfalfa fields that are drinking from the groundwater. We
<br />have many fields that, once established, require no irrigation - although they have a water right
<br />and are considered to be irrigated. Designation of those fields as "temporary dry up" would not
<br />reduce yield ndr consumptive use, thereby injuring downstream users.) So, the way "dry up" is
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