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Introduction: Robert Glennon Redux
I recall a story told by master raconteur Robert Glennon in his seminal book, Water Follies: Groundwater Pumping and the Fate of America's Fresh Waters.
In Chapter 10, 'Size Does Count, At Least for French Fries', Glennon notes America's love for french fries and describes the perfect potato for french fries which the modern fast-food industry craves: white on the inside and not misshapen with knobs and bumps. A steady supply of moisture is essential for these traits. We have Ray Kroc, the McDonald's founder, to thank for expanding our horizons (and waistlines) when it comes to the modern fast-food french fries.
Fast-forward to Minnesota's Straight River Valley, where farmers eked out a living growing crops in the sandy soils. Ron Offutt, an agricultural entrepreneur, realized that irrigation supplied by center-pivot systems fed by wells could produce the uniform, perfect potatoes the fast-food folks needed. So farmers started sinking wells into the shallow and deep aquifers to feed satisfy the french fries demand. Would the wells and agricultural chemicals affect the Straight River and throttle its world-class trout fishery? Robert reported no significant changes when he wrote his book (published in 2002) but noted that a lot more well permits were pending.
What About Wisconsin?
If my post is about Minnesota what's with the title? A lot, actually. Friend and colleague Stuart 'Stu' Schwartz of UMBC sent me an email in which he described a similar situation - potatoes (and other vegetables) and the proliferation of high-capacity wells - in Wisconsin's Central Sands region, underlain by the Central Wisconsin Sand and Gravel Aquifer (CWSGA). The potatoes and wells conjured Robert Glennon's book of 15 years ago.
I recently came across some articles on groundwater management in Wisconsin's Central Sands region. The proliferation of high capacity wells for center pivot irrigation systems supporting a ~$6B ag industry has become associated with dramatic (>10 ft.) drops in lake levels and complete dewatering - turning small local lakes into wetlands.The potato growers association have eagerly pointed out the potential ET losses of substantial plantations of reforested yellow pines (and their shallow rooted ET demands) compared to deep pumping from high capacity wells. (Never mind that ag pumping increases while vegetative ET demand decreases during droughts).
Pressure on Wisconsin groundwater has been building for decades. Scientific studies in the 1960s and 1970s, when the number of high-capacity wells [Note: pumping more than 100,000 gallons per day] in the state numbered in the dozens, predicted that high pumping rates would shrink lakes and dry up streams. Those forecasts have come true, even as Wisconsin’s climate is getting wetter. Last year was Wisconsin’s second wettest in 122 years of record keeping.
The sand and gravel aquifers of central Wisconsin are where groundwater and farm production are most tightly connected. The area’s geologic setting and the rapid growth of irrigated agriculture have aligned to produce worrisome trends in water supply and pollution, nowhere more so than in Portage County.
Speaking of Portage County, Stu mentioned an integrated groundwater flow model of the Little Plover River Basin in the Central Sands area. The model would demonstrate how integrated management might be supported by good science. Stu added:
One of the really nice initial results from their model was showing how the well levels recovered pretty rapidly after pumps were shut off, but the effect on streamflow took months to years to fully recover from just one irrigation pumping cycle.
Here is a model update (April 2016) and video.