Comparative Water Qualities and Blending in the Ogallala and Dockum Aquifers in Texas

Abstract

Within the US Southern High Plains, it is known that the Ogallala Aquifer (OA) has been over pumped since large-scale agriculture began making use of the water in the 1950s. One option to address the decline is to find new water sources. The last 10–15 years have seen an increase in drilling large capacity, deeper wells in the co-located Dockum Aquifer in the Texas Panhandle. This lower aquifer is separated from the OA by low hydraulic conductivity sediment and is thus generally considered independent from the OA. We examined the suitability of the Dockum to supplement OA water by comparing recent water chemistries where the aquifers coexist. We also examined historical information on well yield, well development, and water quality. We found that water quality is equivalent to the Ogallala in some places but in others it is saltier, softer, and more sodic. Use of PCA and hydrochemical facies revealed that even in this small area Dockum water quality is highly variable. We used USGS-PHREEQC to model water blending at ratios of 0–>100% Ogallala. We show that there is irrigation water quality risk no matter the blend, that risks differ according to location, and that the most frequent risks are salinity, sodicity, and nitrate. We conclude that growers can manage these risks if they use blending to choose the risks they feel most apt to mitigate.

Hydrogeochemical Evaluation of Groundwater Quality Parameters for Ogallala Aquifer in the Southern High Plains Region, USA

“…Nitrate is used extensively in fertilizers, which seem to be the main source of nitrate contamination throughout the world. This compound moves very easily after entering groundwater, as it neither absorbs nor precipitates on solids in the aquifer [ 38 , 39 ]. If crops are grown in a soil enriched with fertilizers, a mechanism is created for nitrates to infiltrate the groundwater.…”

Hydrological Characterization and Statistical Analysis of Groundwater Quality for the Ogallala Aquifer in the Permian Basin, Texas, USA

“…There are 4 general classifications of the levels of hardness, these consist of 0-60mg/l (soft water), 61-120mg/l (moderately hard), 121-180mg/l (hard), and anything over 181mg/l is considered very hard. Water becomes hard generally from dissolved ions from sedimentary rocks, like limestone and chalk, and seepage and runoff from soils [39,40]. High levels of hardness can cause health problems, but so can extremely low levels, as one would not be receiving adequate amounts of calcium and magnesium, which are essential for human life.…”

Hydrological Transport and Fate of Brackish and Inorganic Contaminants with Anthropogenic Influence

“…There have been a number of studies on understanding water quality and contaminations in Texas [2][3][4]. In previous studies, Hopkins focused on water quality in the Ogallala Aquifer, where high concentrations of arsenic, fluoride, and nitrate were found in the aquifer [2].…”

“…In previous studies, Hopkins focused on water quality in the Ogallala Aquifer, where high concentrations of arsenic, fluoride, and nitrate were found in the aquifer [2]. In Howell's study, the research compares water quality in the Ogallala and Dockum Aquifer, concluding that the water in the Dockum Aquifer is softer but has a higher TDS concentration than the Ogallala [3]. On the other hand, Strause conducted a study on Texas groundwater quality, determining that Nitrate, Chloride, Fluoride, and TDS are the main contaminants found in excess from wells [4].…”