This study was conducted to provide Grenada, Mississippi an assessment of the current groundwater resources available for use from the Meridian-upper Wilcox Aquifer (MUWX), which is the primary source of groundwater for the city, by creating an accurate groundwater model. Public, private, industrial, and agricultural wells; springs; streams; and surface water bodies all exist within the study area. Groundwater data were collected from local, state, and federal agencies. Well locations, groundwater levels, and well pumping rates were all used in determining the aquifer's characteristics, such as, hydraulic conductivity, discharge, and recharge. Location of the recharge area in relation to a large reservoir was essential in determining the capabilities of recharge to the aquifer, which in turn allowed for a more accurate prediction of groundwater infiltration. Location of wells down-dip of the recharge area was essential in determining the discharge capabilities of the aquifer. This study proved that there is a direct relationship between the current use of the MUWX aquifer in the study area and the ability of the aquifer to recharge sufficiently in order to support its current use. In addition this study also proved that the aquifer would support a large industrial development in the study area and a substantial amount of new public development.

Groundwater is critical in Texas, representing 60 percent of total water used in 2008. Water demands in Texas are projected to increase 22 percent, largely from an almost doubling of population, within the next 50 years; this ever-increasing pressure on Texas water supplies underscores the need to optimize management of water resources. The objective of this study was to assess regulations, scientific information, and rulemaking by groundwater conservation districts (GCDs) that support policies that achieve the legislative intent of GCDs to protect and conserve groundwater resources of the states aquifers. This study's scope was the Carrizo-Wilcox Aquifer and managing GCDs and the following key topics were evaluated 1) management and protection issues; 2) if and how GCDs are utilizing science in development of management plans and rules; 3) whether GCDs are implementing management plans and using enforcement actions; 4) determining if GCDs would have production budgets in conflict with the Regional and State Water Plan and use of the aquifer; 5) and comparing the management plans of GCDs for compatibility. Two online surveys were developed to solicit responses from GCDs and interested parties. Results show that the predominant management issues stemmed from the uncertainty in how groundwater production was regulated and how future permitting would proceed. Environmental interest groups were concerned that GCDs would not adequately incorporate science that supports groundwater production budgets. Stakeholder groups perceived groundwater conservation management as adversely impacting their individual property rights and their region’s ability to develop water management strategies that address projected water budgets. Few formal enforcement actions have been taken by GCDs since 2007. Current water budgets and desired future conditions by the GCDs for the Carrizo-Wilcox Aquifer do not conflict or result in long-term deficits with respect to water budget projections established by the 2011 Regional Water Plans. GCDs adopted groundwater management plans that addressed goals including conservation and recharge, as outlined in the Texas Water Code, by creating varied objectives and standards. Unanimous public acceptance of the management plans and rules established by the GCDs may never be accomplished, but acceptance will improve through the continuation of public communication, stakeholder coordination, and education. / text

This study aims to integrate groundwater geochemistry and mathematical modeling to determine the dominant geochemical processes and groundwater residence time within the Wilcox aquifer in the northern Gulf Coastal Plain. Groundwater samples were collected and analyzed for major ion chemistry, stable isotopes (18O, 2H, and 13C), and radioisotope 36Cl content. Geochemical modeling enabled the identification of major sources and sinks of solutes in the aquifer. A two-dimensional, finite-difference, numerical model was used to determine the deep groundwater flow rate and transport of 36Cl in the aquifer. Major ion chemistry shows a chromatographic pattern along the flow path in which a gradual increase of Na+ and decrease of Ca2+ and Mg2+ is evident. The most plausible inverse models in the downgradient section of the aquifer indicate that oxidation of organic matter (OM), which may be associated with discontinuous lenses of lignite, and consequent release of CO2 sustain the reduction of Fe(III) (oxyhydr)oxides and sulfate and the dissolution of carbonate minerals (calcite and, in some instances, siderite). These processes, in turn, result in pyrite precipitation and exchange of Ca2+ for Na+ on clay-mineral surfaces. Models constrained with 13C are consistent with mole transfers between pairs of wells in close proximity, but not for the entire flow path. The observed range of δ13C of dissolved inorganic carbon (-7.3‰ to -12.4‰) is interpreted as a result of both oxidation of OM and dissolution of carbonates. Calculated values of 36Cl/Cl show an abrupt discontinuity between the upgradient and downgradient sections that was also observed in δ18O and δ2H data. The gradual enrichment of 18O and 2H along the flow path could be the result of diffusion. The distinct differences in δ18O and δ2H between the upgradient and downgradient Wilcox aquifer suggest that the latter preserves a paleoclimatic signal.