Culberson County Groundwater Conservation District
Culberson County is located on the New Mexico state line in Far West Texas. It is bordered on the east by Reeves and Jeff Davis counties and on the west by Hudspeth County. The Culberson County Groundwater Conservation District (CCGCD) was formed as a taxing entity in 1998. It has jurisdiction over “the entire portion of the Igneous and West Texas Bolsons aquifer that is within the county” and “the large majority of the portion of the Capitan Reef Complex that is within the county,” according to the district’s most recent groundwater management plan. This includes “100% of the commercial irrigated agriculture and municipal use (City of Van Horn) within the county.”
Culberson County was the focus of intense reporting several years ago, when the district sought to expand its boundaries. As the Van Horn Advocate reported back in 2018, the CCGCD “boundary is comprised of approximately 1,740 square miles of the 3,813 square miles within the county (about 46%). There is no groundwater district covering the 2,073 square miles within the county … (proposed Expansion Area) … [leaving] an island of land [where] water use [is] not monitored.” The aquifers underlying this “proposed Expansion Area” contain mostly brackish water, which is defined by the Texas Water Development Board (TWDB) as “water containing total dissolved solid (TDS) concentrations of between 1,000 and 10,000 milligrams per liter” which is unsuitable for human consumption unless it is treated.
In explaining why the district had originally been created to encompass less than half of the county, the district’s then general manager Summer Webb told the Texas Standard that the district “was formed mostly for the protection of the aquifers that were being used … Nobody really thought about brackish water being important back in the day.” But, according to the Advocate, “extensive oil and gas development within the Expansion Area” had increased groundwater use there “by a factor of 10 to 1000 times.” The uptick in brackish groundwater withdrawals gave rise to concerns about potential impacts on the aquifers within the original district boundaries because brackish groundwater’s connections to subterranean freshwater are poorly understood. In some aquifers, the brackish layer can be well separated from nearby freshwater by hundreds of feet of less permeable rocks. In other aquifers, the two types of water can be so closely connected that they form a continuum, such that withdrawing brackish groundwater can eventually have impacts on freshwater levels in a given aquifer.
Expanding the boundaries to cover all of Culberson County would have enabled the district to gather the data necessary to better understand these potential impacts. This work is considered especially important because the unmonitored area of Culberson County forms a missing jigsaw piece in the region’s groundwater puzzle precisely where scientists believe the primary source of the beloved spring-fed pool at Balmorhea State Park is located. Despite the CCGCD’s best efforts to expand its boundaries, the necessary legislation ultimately failed to pass the Texas Legislature.
Even without jurisdiction over all the aquifers in the county, the CCGCD currently has plenty on its plate with “the drawdown rate of the Lobo Flat Aquifer,” according to current General Manager Haley Davis. “The district has been working diligently with our hydrogeologist and stakeholders to put in recharge wells to hopefully help with this issue,” she said. Straddling the Culberson-Jeff Davis County line, the Lobo Flat Aquifer is a section of the West Texas Bolsons Aquifer and supplies groundwater to one of the most intensively farmed areas in the county. The heavy dependence of agricultural operations on the aquifer, along with diminishing rainfall in the area, has caused groundwater levels in the Lobo to drop. Local users have been very cooperative in voluntarily reducing pumping, according to Davis. But the district is exploring ways, such as managed aquifer recharge (MAR), to actually get more water into the aquifer.
District hydrogeologist Steve Finch and his team evaluated the aquifer “for locations in which MAR would be the most effective … [using] well logs obtained from the … TWDB database … to identify low-permeability layers that occur above the water table.” By constructing a computer model of these layers, the team was able to use a “soil coverage map” from the Natural Resource Conservation Service to “rank areas … where low-permeability layers were relatively thin and the soil type promoted a high rate of infiltration,” explained Finch. “We then overlayed the MAR suitability areas with estimated stormflow … and found that in most places shallow caliche layers and shallow subsurface clay prevented recharge to the more permeable underlying sediments and water table.” The solution they recommended was to install “shallow holes filled with gravel that drilled past the caliche horizon so captured stormwater runoff could more readily infiltrate.”
But, as with nearly all innovative solutions to Texas’ many water challenges, the state’s outmoded regulatory structure is proving to be the largest obstacle to progress. The Texas Commission on Environmental Quality “permitting for shallow holes filled with gravel is overly burdensome,” said Finch, because “shallow holes or depressions are considered Class V injection wells” and these involve ongoing sampling and testing procedures to prove that the water is safe. Finch argues that this classification is out-of-touch with reality and stems mainly from the state’s lack of options for classifying nature-based aquifer recharge features. Since the water table is more than 300 feet down from the surface, Finch argues, “there is ample natural sediment that would filter the recharge” before it reached the aquifer. In order to get around this insurmountable hurdle, Finch is going to “recommend better use of spreader dams in the few identified recharge … areas where shallow caliche and clay appear to be absent.”
Despite these setbacks, Davis remains hopeful. “The district is doing everything possible to keep water available for many years to come in Culberson County,” she said.
Trey Gerfers serves as general manager of the Presidio County Underground Water Conservation District. A San Antonio native, he has lived in Marfa since 2013 and can be reached at tgerfers@pcuwcd.org.