Maps

Fern Cave in Jackson County, Alabama, is a 15.6-mile-long (25.1-kilometer) cave system, managed by the U.S. Fish and Wildlife Service and Southeastern Cave Conservancy, that has the second highest biodiversity of any cave in the southeastern United States. Groundwater in karst ecosystems is known to be susceptible to impacts from human-induced land-use activities in watersheds that contribute rech

Introduction The Mississippi Alluvial Plain is one of the most important agricultural regions in the United States, and crop productivity relies on groundwater irrigation from an aquifer system whose full capacity is unknown. Groundwater withdrawals from the Mississippi River Valley alluvial aquifer have resulted in substantial groundwater-level declines and reductions in base flow in streams with

The U.S. Geological Survey constructed the potentiometric surface of the Upland terrace and upper Ponchatoula aquifers and the “400-foot” sand using the altitude of water levels from 121 wells measured January 2014 to March 2015. Differences in water levels in the Upland terrace and upper Ponchatoula aquifers and “400-foot” sand were measured at 55 wells in 2009 and again at the same wells in 2014

In August 2019, the U.S. Geological Survey, in cooperation with the Puerto Rico Electric Power Authority, conducted a bathymetric survey of Lago Patillas to update stage-volume data in order to determine the sediment infill rates and to generate a bathymetry map. Water-depth data were collected along predefined lines using single-beam depth sounder and Differential Global Positioning System techno

Machine-learning models developed by the U.S. Geological Survey were used to predict iron concentrations and the probability of dissolved oxygen (DO) concentrations exceeding a threshold of 1 milligram per liter (mg/L) in groundwater in aquifers of the Mississippi embayment physiographic region. DO and iron concentrations are driven by and reflect the oxidation-reduction (redox) conditions in grou

Regional aquifers in the Mississippi embayment are the principal sources of water used for public and domestic supply, irrigation, and industrial uses throughout the region. An understanding of how water quality varies spatially, temporally, and with depth are critical aspects to ensuring long-term sustainable use of these resources. A boosted regression tree (BRT) model was used by the U.S. Geolo

Water levels were determined in 90 wells to prepare 2011–12 potentiometric surfaces focusing primarily on the “200-foot,” 500-foot,” and “700-foot” sands of the Lake Charles area, which are part of the Chicot aquifer system underlying Calcasieu and Cameron Parishes of southwestern Louisiana. These three aquifers provided 34 percent of the total water withdrawn and 93 percent of the groundwater wit

The karstic Edwards and Trinity aquifers are classified as major sources of water in south-central Texas by the Texas Water Development Board. During 2018–20 the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, mapped and described the geologic framework and hydrostratigraphy of the rocks composing the Edwards and Trinity aquifers in northern Medina County from field obse

A potentiometric surface map of the South Coast aquifer near Santa Isabel, Puerto Rico, was created from data collected during a synoptic survey of groundwater levels at 55 wells from March 31 to April 17, 2014. Measured groundwater level values ranged from −22.8 to 185.4 feet above mean sea level. During the study period, cumulative rainfall of 0.65 inch was recorded in the study area. Measuremen

During January 23–30, 2018, the U.S. Geological Survey, in cooperation with the Puerto Rico Electric Power Authority, conducted a bathymetric survey of Lago Carite primarily to update estimates of the contemporary reservoir storage capacity and sedimentation rate. Previously designated transect lines were surveyed by using a depth sounder coupled to a differential Global Positioning System to gene

The Boone and Roubidoux aquifers (or their equivalents) are the main sources of fresh groundwater in northeastern Oklahoma. Projected total water demand of both surface water and groundwater in northeastern Oklahoma is expected to increase approximately 56 percent from 2010 to 2060. This report provides an overview of the hydrogeology of northeastern Oklahoma, with an emphasis on the hydrogeologic