By Quintin Muhlenkamp
Darke County Parks
Water is not an afterthought here in Darke County. Our largely agricultural economy benefits from a productive amount of yearly rainfall. We are aware when the ground is too dry, and we rejoice at the end of a summer drought. Rejoice. Because we rely on rainfall. The majority of farm ground in Darke County is unirrigated for the simple reason that irrigation is not necessary. Relying on our good soil, and dependable weather patterns, we do pretty good. In 2017 the USDA ranked Darke as 157th of nearly 3000 U.S. counties in total grain sales. Not bad, but this is something we are all familiar with. Farther west agriculture is a different story.
The 100th meridian is a longitudinal line used by explorer John Wesley Powell (of Grand Canyon fame) as the dividing line between the east and the arid west. This imaginary line runs through the great plains, cutting the Dakotas, Nebraska, and Kansas in half. Imaginary, but drive across Nebraska and you can almost see it with your own eyes. Muddy forest trails turned dusty grassland; great oaks replaced with sword blade yucca. This is the land of irrigated agriculture.
Irrigation, practiced by the earliest of people in the arid West, offers a means to produce on a large scale. The ability to pull water from a river, reservoir, or subterranean aquifer and apply to crops at vital stages of growth can turn some of the driest regions into agricultural powerhouses. Think Southern California. Divert enough of the Colorado River and you can turn the Mojave Desert into the country’s most productive produce farm. The sheer amount of irrigated water necessary to sustain large scale agriculture is astonishing. Take an example from the potato, a crop that thrives in sandy, well-drained soil. Just the kind of soil abundant in Idaho’s Snake River Plain, where some areas can require more than 10 feet of water to raise a crop. This area of southern Idaho averages less than 15 inches of rain per year. Yes, that’s approximately nine feet of water diverted onto Idaho’s vast, and famous, potato crop. Public water use on such a scale is monitored and managed to ensure this limited and valuable resource is reliably available for beneficial use. This is a significant challenge in the arid states, as some regions demand watering crops faster than the sources can be replenished.
This is the case of the Ogallala aquifer. This expanse of groundwater, one of the largest in the world, underlays much of the great plains, and, in turn, supplies much of the water necessary to sustain plains agriculture. High withdraw rates have resulted in areas of the aquifer being severely depleted. A depleted aquifer may, or may not, recharge as water slowly moves through the subsurface, leaked-in through rivers or rain. Whether or not it recharges, and how long this takes, depends on local geology, and, of course, weather patterns.
Determining these so-called recharge rates, and therefore estimating allowable pumping rates, is a question I would like to tackle starting this fall at the University of New Mexico. New Mexico has a rich agricultural history, dating back 2500 years, sustained despite the state’s lack of water and episodic droughts. With depleting aquifers such as the Ogallala that are important for New Mexico’s agriculture, the time is right for mapping the state’s groundwater movements. I will be working with Dr. Eric Lindsey, an expert in the motion of Earth’s surface, to measure the small motions resulting from extraction and recharge as I work to complete a doctorate degree in Earth Science.
As I prepare to move to New Mexico I am reminded of the thanks I owe to Darke County Parks. I have been involved with DCP for as long as I am able to remember, through participating in their numerous summer programs, volunteer work, and currently as a maintenance technician. The parks have helped to instill in me a passion for nature, one that I bring with me to New Mexico in effort to understand water below the surface, a resource essential to the livelihood of farmers west of the 100th meridian.
