Dr. Vance Kennedy has long been concerned that too many people ignore the long-term hazards of drip irrigation, especially in terms of increased soil salinity and reduced groundwater recharge. A recent Modesto Bee editorial criticizing water subsidies for farmers provoked the following reaction from Dr. Kennedy, an award-winning hydrologist who is retired from the U.S. Geological Survey:
I am a 93 year old retired research hydrologist who is concerned about the future of this region. I believe we have an obligation to plan ahead for future generations, and this is my effort to have community leaders look ahead. I anticipate sending this note to a range of local leaders in the hope the views presented here will be given some consideration, especially when compared to those espoused by the Modesto Bee in a recent editorial. I welcome comments.
In a June 10 editorial, The Modesto Bee argued emphatically that the Modesto Irrigation District’s practice of subsidizing water for agriculture should be abandoned and added that the, “MID must make electricity customers a top priority.” I strongly disagree, if they mean to greatly increase flood irrigation rates and remove entirely the so-called “subsidy.” What has not been recognized is that there has long been a two-way subsidy between Modesto residents and nearby farmers. The farmers recharge the water supply under the city of Modesto at no charge to the city, and, in exchange, electric rate payers help cover irrigation costs.
The value of a long term reliable water supply and maintenance of agriculture and related jobs far exceeds the importance of electricity rates. Without water and agriculture, this area would be an economic disaster. Bee editors are concerned about the poor having to pay high electric bills, but at least poor people have jobs with some income. If we lose farm income, we will lose jobs and income throughout the region.
If all farmers go to drip irrigation because of high flood irrigation rates, the water table can be expected to decline rapidly, resulting in greatly increased pumping costs and ultimately placing us in the same dire circumstances as the Westlands Water District, where subsidence, depleted groundwater supplies, and soil salinity have driven surface water prices upward beyond sustainability. Rumor has it that the irrigation charge here could go more than twenty times beyond the present rate. The impact on the economy is impossible to predict, but it could be major.
The Bee overwhelmingly emphasizes the electricity rates and gives essentially no recognition to the benefits of past and present low irrigation rates, which encouraged farmers to keep flood irrigating so that the water table recharged. I have spoken to a Bee editor friend and have simply agreed to disagree. Since I have been unable to get the Bee to recognize my arguments and give them serious consideration, I have decided to present my views elsewhere.
It is true that irrigation rates have been very low in the past and apparently have been “subsidized.” In return, agriculture has assured a reliable groundwater supply superior to most other areas in the Valley and provided huge economic support to Valley communities. Last year, Stanislaus County farm products were valued in excess of four billion dollars. A common assumption, known as the “multiplier,” is that those dollars cause three times their value in local economic activities or perhaps twelve billion dollars in one year.
If we assume that MID farmers account for only a quarter of the county’s agricultural income, the value is about three billion dollars. Contrast that figure with the hundred million dollars over perhaps ten years of claimed “subsidy” by the Bee, or perhaps ten million dollars per year. The ratio of economic benefit to cost for the community is about three-hundred thousand to one. Where else can you get that sort of return year after year? If a new industry producing three billion dollars per year were considering coming to town, what sort of “subsidy” would be offered? I am sure it would be a lot. The Bee would not be fighting it, and the Chamber of Commerce would rave about it.
Farmers are already going to drip irrigation on a large scale and increased irrigation rates will simply encourage much more of that practice. It does reduce water use and is very convenient. The short-term benefits are obvious, and the long-term harm is ignored. Any good politician knows to push for short-term benefits, just as any newspaper does.
The long-term harm includes greatly reduced groundwater recharge and a buildup of salinity in soils. The State has finally recognized, to a limited degree, the value of groundwater in a warming, and perhaps drier, climate. Because there is a lot of inertia in natural systems, depletion of groundwater will occur gradually in our area. Such depletion has already occurred elsewhere in the Valley and the consequences were soil salinity and subsidence wherever there are clays in the geologic profile. Those consequences can be avoided here if we just encourage farmers to continue flood irrigation, the opposite of what the Bee’s efforts recommend. The general public is not concerned until depleted groundwater becomes a major problem. By that time, the danger will be virtually irreversible. Meanwhile, the Bee addresses only immediate problems and fails to look long term.
What will we do years from now, when we have depleted our supply of good groundwater? It is the old case of unintended consequences.
I have long been interested in learning how to measure the percentage of flood irrigation water recharging the water table. To my knowledge, there is at present no accurate method of doing this. I believe that many past studies have relied on estimating evaporation of the flood irrigation waters and transpiration by plants. Knowing the volume of water applied and estimating those two factors, with accompanying errors, the remaining amount is considered groundwater recharge.
There have been efforts in the past to do a better job of estimating groundwater recharge, but none locally, to my knowledge. It would be extremely beneficial to everyone if an accurate measure of such recharge were available. With an accurate measure of groundwater supply to cities, I believe a case could be made for paying farmers for groundwater recharge. Perhaps such an accurate measure would encourage us to reevaluate and revise our understanding of the agricultural “subsidy.” In that light, we might even be more than happy to continue encouraging farmers to maintain sound and sustainable flood irrigation practices.