In a presentation at the Water in the Desert Conference at Sul Ross State University, Dr. Kevin Urbanczyk of the Rio Grande Research Center explained that the health of our springs, which are dependent on recharge from rainwater, is complicated in our region because this recharge has “to get to the right geology to enter the aquifer.” Groundwater pumping is another reason that many of the springs in the Big Bend region no longer flow. A further concern is a local decrease in precipitation as the result of climate instability. Urbanczyk cautioned that we need to “shift to conservation as we see change in precipitation.”
The importance of spring systems cannot be overstated. Urbanczyk described one spring system in the Lower Canyons of the Big Bend that contributes more water to the Rio Grande each year than the entire Conchos River. The Conchos flows out of Chihuahua and replenishes the so-called “Forgotten Reach,” a segment of the Rio Grande between Fort Quitman and Presidio that is notoriously starved of flow due to overallocation upstream. Urbanczyk emphasized that springs are particularly significant because they provide “windows into the aquifer.” In other words, spring health reflects aquifer health.
Most springs are generally understood to be either artesian springs (where water issues from the rock under natural pressure underground until it reaches a land surface) or gravity springs (where water is pulled down through the ground under the force of gravity until it reaches a confining layer it can’t penetrate, which forces the water to flow horizontally along this layer until it reaches an opening and comes out as a spring). Springs can also be considered perennial (in other words, flowing continuously throughout the year) or intermittent (where water from rainfall or snowpack supplies sufficient water to enable the spring to flow at disparate times throughout the year).
A recently published study titled “Revisiting Gunnar Brune’s ‘Major and Historic Springs of Texas’ with an Analysis on the Fractal Character of Springflow” by Dr. Robert Mace and Nohemi Galaviz takes a broad look at the current health of the state’s springs based on historical data. Brune’s 1975 report identified 281 major and historic springs in Texas, while his self-published 1981 book titled “The Springs of Texas: Volume 1” included some 2,900 springs. Both works, which classify springs as flowing, intermittent, dry, or inundated, remain the broadest available surveys of springs in Texas. Mace and Galaviz confine their analysis to sites that appear both in Brune’s report and his book, for a total of 179 springs.
In their study, Mace and Galaviz provide a fascinating description of their resourceful methods to locate and verify the flow status of each spring using USGS topographic sheets, Google Maps and Google Earth Pro, the Groundwater Data Viewer of the Texas Water Development Board, the Texas Springs Facebook Group, and conventional site visits. Their analysis seeks to corroborate Brune’s numbers with the numbers in their own database, compare recent assessments of flow status with Brune’s 1975 report, and compare the flow status of springs between the report and the book. They found that a “total of 52 springs changed their flow status from the 1975 report to today: 35 went from flowing to dry, 1 went from intermittent to flowing, 10 went from flowing to intermittent, 4 went from flowing to inundated, 1 went from dry to flowing, and 1 went from dry to intermittent.” They go on to summarize their findings as follows: “By the time Brune published his book in 1981, 11 to 14 percent of the major and historical springs he investigated had gone dry. More recently, based on the present study, 23 to 30 percent of the springs have now gone dry … over the past 50 or so years.”
The widely shared assumption that major springs will always flow has been dramatically challenged in recent years. Examples of disappearing springs range from Instagram favorite Jacob’s Well outside Austin to the obscure, majestic waters of Las Moras Springs near Brackettville. Like Urbanczyk, Mace and Galaviz warn that “springs serve as sentinels for aquifer health” and provide “an important indicator of sustainable production.” As groundwater pumping continues to increase and precipitation patterns change, Urbanczyk urges a “change in mindset” to preserve these features before it’s too late.
To view the complete study by Mace and Galaviz, including their fractal analysis of springflow, visit www.meadowscenter.txst.edu/research/environmental-flows/revisiting-major-historical-springs.html. Their database and report are also available to the scientific community as an updatable research tool.
Trey Gerfers is a San Antonio native and serves as general manager of the Presidio County Underground Water Conservation District. He has lived in Marfa since 2013.