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At least 433 records · Page 24Linked to original sources
USGS2022

Drainage infrastructure and groundwater system response to changes in sea level and precipitation, Broward County, Florida

Executive Summary Southeast Florida is highly susceptible to flooding because of its low topography and porous, highly permeable Biscayne aquifer. Rising seas will likely result in increased groundwater levels in parts of Broward County, Florida, that will reduce available soil storage and therefore increase the likelihood of inundation and flooding from precipitation events. Moreover, rising seas may also reduce the capacity of the coastal water-control structures to discharge inland waters to tidal areas, thereby increasing surface-water stage and nearby groundwater levels. Increased rainfall intensity will likely further increase peak surface-water stages and groundwater levels, more quickly fill the reduced soil storage capacity, and increase the likelihood for inundation. Managers and planners in Broward County, Florida, face the challenge of understanding and preparing for the consequent risk to residents, businesses, and critical infrastructure posed by increased sea level and precipitation. The U.S. Geological Survey, in cooperation with the Broward County Environmental Planning and Resilience Division, has developed a groundwater/surface-water model to evaluate the response of the drainage infrastructure and groundwater system in Broward County to projected increases in sea level and potential changes in precipitation. The model was constructed using Modular Finite-Difference Groundwater Flow Model Newton formulation, with the surface-water system represented using the Surface-Water Routing process and the Urban Runoff process. The aquifer layering and flow parameters rely heavily on existing hydrologic flow models developed by the U.S. Geological Survey for the same model area. The surface-water drainage system within this newly developed model actively simulates the extensive canal network using level-pool routing and active structures representing gates, weirs, culverts, and pumps. Steady-state and transient simulation results represented historical conditions (2013–17). The simulated historical groundwater levels and upstream stage and flow at the primary structures generally captured the behavior of the actual hydrologic system. Simulation results incorporating increased sea level and precipitation were used to evaluate the effects of these projected changes on the surface-water drainage system and wet season groundwater levels. Four future sea-level scenarios were simulated by modifying the historical inputs for both steady-state and the transient versions of the model to represent mean sea levels of 0.5, 2.0, 2.5, and 3.0 feet (ft) above the North American Vertical Datum of 1988. These mean sea levels correspond to sea-level rises of 1.05, 2.55, 3.05, and 3.55 ft, respectively, above the 2013–17 mean measured tidal stage. Additional simulations represented a 15-percent increase in rainfall rates using the transient model and a 15-percent increase in rainfall recharge using the steady-state model. The simulated results indicated that (1) the effects of increased sea level were more evident in the easternmost, coastal areas of the county where increases in groundwater levels are nearly equivalent to sea-level rise; (2) groundwater levels west of the coastal water-control structures only changed slightly in response to increased sea level for most scenarios; (3) when the control elevations of the gravity-controlled coastal water-control structures were surpassed by sea-level rise, the resulting increases in upstream stage in the connected primary canal resulted in increased groundwater levels that can propagate into the western parts of the county; (4) the historical west-to-east downward gradient in groundwater levels decreased with increased sea level, and groundwater levels were lower in central parts of the county than areas west and east for the higher sea-level scenarios; (5) simulated upstream stage for most of the primary coastal water-control structures increased with increased sea level, with the largest increases occurring at gravity-controlled structures having the lowest control elevations; (6) total flow through the primary structures increased as sea level increased because of additional groundwater leakage into the surface-water network; (7) the 3.0-ft mean sea-level rise scenario resulted in an increase of 37.10 square miles in area having a wet season average depth to groundwater of less than 2 ft, and an increase of 22.84 square miles in newly inundated areas compared to historical simulation results; and (8) a 15-percent increase in rainfall rate for the entire simulation period produced little increase in upstream stages at the primary structures and an increase in total flow through the primary structures proportional to the increase in rainfall.

Florida↗
USGS2025

Stream network capacity to support beaver dams in the Tualatin River Basin, northwestern Oregon

Significant Findings Beaver dams can help streams connect to their floodplains. These floodplain connections can expand the range of available aquatic habitats and aid in the restoration of stream and floodplain function and processes. American beavers ( Castor canadensis ) occupy a wide variety of aquatic habitats; however, their ability to build dams, the agent of stream and floodplain change, is constrained in large part by three physical variables—local vegetation, topography, and hydrology. These three physical variables are combined in the Beaver Restoration Assessment Tool (BRAT), a geographic information system-based utility that uses a Fuzzy Inference System (FIS) to estimate the capacity of each reach within a stream network to support beaver dams. In this study, version 1.0 of BRAT was adapted and applied to the entire perennial stream network of Tualatin River Basin in northwestern Oregon. Beaver-dam locations in the Tualatin River Basin were compiled to (1) define the distribution of dams in the basin during 2013–16 and (2) provide necessary data for calibrating and validating BRAT predictions. BRAT was calibrated to the current known distribution of dams, as compiled in the inventory. The input FIS equations of the original BRAT model were adjusted to account for local topographic conditions; specifically, the low gradient of many streams in the basin, although subsequent updates to BRAT may obviate the need for these changes. Results from this modified BRAT model reasonably simulated the dam inventory. Results show that beavers can currently build the greatest density of dams, defined as number of dams per kilometer of stream, in the higher-gradient forested streams of the basin, whereas they can build the fewest number of dams per kilometer in urban streams along the lower-gradient valley floor. Estimated dam density was generally 5-15 dams per kilometer (km) for forested streams and 2-4 dams/km for urban streams. Improving riparian vegetation along urban streams may allow beavers to build on average four additional dams per kilometer compared to current conditions. Results from this study may help inform local stream and stormwater management by (1) identifying stream reaches with the most potential to support beaver dams, (2) determining the likely factors limiting potential for dam building, and (3) identifying potential areas where dam building may affect human infrastructure.

Oregon↗
USGS2005

Chemical characteristics of ground-water discharge along the south rim of Grand Canyon in Grand Canyon National Park, Arizona, 2000-2001

Springs flowing from the south rim of Grand Canyon are an important resource of Grand Canyon National Park, offering refuge to endemic and exotic terrestrial wildlife species and maintaining riparian areas. Population growth on the Coconino Plateau has increased the demand for additional development of ground-water resources, and such development could reduce spring discharge and affect the sustainability of riparian areas within the park. In addition, springs are an important source of drinking water for hikers and are culturally and economically important to Native Americans living in the region. Water samples were collected from May 2000 to September 2001 from 20 spring and creek sites that discharge water from the Redwall-Muav Limestone aquifer along the south rim of Grand Canyon. Sample collection sites were described and samples were analyzed for major ions, nutrients, trace elements, radioactivity, and selected isotopes, and potential sources of ground-water flow to the springs. Rock samples representing the major stratigraphic units of Grand Canyon were collected near the Bright Angel Fault and analyzed for mineralogy, strontium-87/strontium-86, and carbon-13/carbon-12. The chemical composition of water samples collected from a given spring did not vary appreciably over the course of the study. Although water at each spring had a temporally constant composition, the composition was chemically distinct from that of every other spring sampled, indicating spatial variability in the ground-water composition. Most samples had a calcium magnesium bicarbonate composition; a few had a substantial sulfate component. Concentrations of arsenic, nitrate, selenium, uranium, and gross alpha approached or exceeded U.S. Environmental Protection Agency Maximum Contaminant Levels in water discharging from some springs. Oxygen and hydrogen isotopic compositions varied little among samples, and for most sites the isotopic data plot close to the global meteoric water line or below the local meteoric water line. Isotopic enrichment indicates fractionation due to evaporation occurs at some sites. The evaporative process may occur prior to recharge or post-discharge. Flow paths are differentiated between the eastern part of the study area where strontium-87/strontium-86 values for water from springs and creeks are more radiogenic than strontium-87/strontium-86 values for water that discharges from sites farther west. Tritium and carbon isotope analyses indicate that residence time of ground-water discharge from springs and creeks ranges from less than 50 years to about 3,400 years. Water with a residence time of less than 50 years is absent at several sites. Discharge of most springs and creeks is a mixture of younger and older waters.

Arizona↗
USGS2023

Status of water-level altitudes and long-term and short-term water-level changes in the Chicot and Evangeline (undifferentiated) and Jasper aquifers, greater Houston area, Texas, 2022

Since the early 1900s, groundwater withdrawn from the primary aquifers that compose the Gulf Coast aquifer system—the Chicot, Evangeline, and Jasper aquifers—has been an important source of water in the greater Houston area, Texas. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting the status of water-level altitudes and water-level changes in these aquifers in the greater Houston area. In this report, the Chicot and Evangeline aquifers are treated as a single hydrogeologic unit for the purposes of providing annual assessments of regional-scale water-level altitudes and changes over time. In 2022, shaded depictions of water-level altitudes for the Chicot and Evangeline aquifers (undifferentiated) ranged from about 270 feet (ft) below the North American Vertical Datum of 1988 (NAVD 88) to about 195 ft above NAVD 88. The largest decline in water-level altitudes indicated by the 1977–2022 long-term water-level-change map was southeast of The Woodlands. In comparison, the 1990–2022 long-term water-level-change map depicts declines in water-level altitudes in localized areas at or near certain wells in parts of northwestern Harris County and southern Montgomery County. The largest rise in water-level altitudes for 1977–2022 was observed in a relatively large area in southeastern Harris County, whereas the largest rise in water-level altitudes for 1990–2022 was observed in a relatively small area in central Harris County. The 5-year short-term water-level-change map depicts the largest declines at three wells in northern Fort Bend County and the largest rises at five wells in southwestern and central Harris County. The 1-year short-term water-level-change map depicts the largest decline at a well in north-central Harris County and the largest rises at a well in north-central Fort Bend County and a well in southwestern Harris County. In 2022, shaded depictions of water-level altitudes for the Jasper aquifer ranged from about 213 ft below NAVD 88 to about 285 ft above NAVD 88. The 2000–22 long-term water-level-change map depicts water-level declines throughout most of the study area where water-level-measurement data from the aquifer were collected, with the largest decline in north-central Harris County and south-central Montgomery County south of The Woodlands. The 5-year short-term water-level-change map depicts the largest decline at a well in Conroe and the largest rise at a well in south-central Montgomery County. The 1-year short-term water-level-change map depicts the largest decline at a well in south-central Montgomery County east of The Woodlands and the largest rise at a well in Conroe.

Texas↗
USGS2008

Geologic map of the Camas Quadrangle, Clark County, Washington, and Multnomah County, Oregon

The Camas 7.5' quadrangle is in southwestern Washington and northwestern Oregon approximately 20 km east of Portland. The map area, bisected by the Columbia River, lies on the eastern margin of the Portland Basin, which is part of the Puget-Willamette Lowland that separates the Cascade Range from the Oregon Coast Range. Since late Eocene time, the Cascade Range has been the locus of an episodically active volcanic arc associated with underthrusting of oceanic lithosphere beneath the North American continent along the Cascadia Subduction Zone. Bedrock consists largely of basalt and basaltic andesite flows that erupted during late Oligocene time from one or more vents located outside the map area. These rocks crop out only north of the Columbia River: at the base of Prune Hill in Camas, where they dip southward at about 5°; and east of Lacamas Creek, where they dip to the southeast at 15 to 30°. The volcanic bedrock is unconformably overlain by Neogene sediments that accumulated as the Portland Basin subsided. In the Camas quadrangle, most of these sediments consist of basaltic hyaloclastic debris generated in the volcanic arc to the east and carried into the Portland Basin by the ancestral Columbia River. The dominant structures in the map area are northwest-striking dextral strike-slip faults that offset the Paleogene basin floor as well as the lower part of the basin fill. The Oligocene rocks at Prune Hill and to the east were uplifted in late Pliocene to early Pleistocene time within a restraining bend along one of these dextral faults. In Pleistocene time, basaltic andesite flows issued from a volcano centered on the west side of Prune Hill; another flow entered the map area from the east. These flows are part of the Boring volcanic field, which comprises several dozen late Pliocene and younger monogenetic volcanoes scattered throughout the greater Portland region. In latest Pleistocene time, the Missoula floods of glacial-outburst origin inundated the Portland Basin. The floods deposited huge bars of poorly sorted gravel in the lee of Prune Hill and west of the Sandy River. Volcanic debris from Mount Hood form a prominent delta at the mouth of the Sandy River. This map is a contribution to a program designed to improve geologic knowledge of the Portland Basin region of the Pacific Northwest urban corridor, the densely populated Cascadia forearc region of western Washington and Oregon. More detailed information on the bedrock and surficial geology of the basin and its surrounding area is necessary to refine assessments of seismic risk, ground-failure hazards and resource availability in this rapidly growing region.

Oregon, Washington↗
USGS2015

Evaluation of the effects of sewering on nitrogen loads to the Niantic River, southeastern Connecticut, 2005-2011

Nitrogen concentration data were collected from 20 wells near the Niantic River Estuary, during 18 sampling periods from 2005 through 2011, as part of a study to determine changes in nitrogen concentrations and loads as a result of sewering on the Pine Grove peninsula in Niantic, Connecticut. The Pine Grove peninsula area is a neighborhood of 35 acres containing 172 residences with onsite wastewater treatment systems at the beginning of the study in 2005. From 2008 through 2009, the residences were connected to a newly installed sewer system. Water-quality data collection continued from 2010 through 2011, after the sewers were installed. The peninsula is underlain by glacial stratified deposits. The freshwater in this aquifer ranges from 10 to 45 feet (ft) in thickness and overlies saline groundwater. The mean water-table altitude was from 0.09 to 0.97 ft above the North American Vertical Datum of 1988, with a horizontal hydraulic gradient of 0.0004 to 0.0005. Initial sampling of the wells included analysis for nutrients, major ions, boron, bromide, and dissolved gases. Concentrations of nitrate plus nitrite nitrogen from the initial sampling ranged from 0.94 to 20 milligrams per liter (mg/L) in samples collected spatially and with depth in the aquifer. The mean concentration of total dissolved nitrogen before the sewers were installed was 7.5 mg/L, and dissolved gas analyses indicated little or no denitrification in the aquifer. Chloride to bromide ratios and boron analysis of the initial water samples confirmed that wastewater was a source of groundwater recharge to most of the wells. Annual recharge from onsite wastewater-disposal systems in 2006 was 4.98 inches, based on analysis of water-use data. Concentrations of total dissolved nitrogen decreased following sewering in samples from most of the wells that were identified as having nitrogen related to wastewater discharge. Concentrations of total dissolved nitrogen in individual wells decreased by as much as 11.7 mg/L between the periods before and after the sewers were installed, and the mean concentration of total dissolved nitrogen in all wells decreased by 2.3 mg/L to a mean concentration of 5.2 mg/L. Nitrogen loads from groundwater in the Pine Grove peninsula area were estimated for three time periods by using the measured mean concentrations of total dissolved nitrogen and estimated recharge rates. The estimated nitrogen load before sewering was 1,675 pounds per year (lb/yr) and following sewering was 963 lb/yr. Mean concentrations of total dissolved nitrogen were assumed to have been reduced to 1.1 to 2.3 mg/L after the aquifer had stabilized and sewage-related nitrogen had been completely discharged from the system, with an estimated future load of 202 to 423 lb/yr. Nitrogen loads from groundwater discharge to the Niantic River Estuary from the lower part of the Niantic River watershed, including Pine Grove, were estimated to be 18,800 pounds (lb) in 2011. This compares with an additional 51,000 lb from the surface-water tributaries to the estuary and an unknown quantity of nitrogen load from stormwater runoff in the lower Niantic watershed.

Connecticut↗
USGS2016

Geology, hydrology, water quality, and potential for interbasin invasive-species spread by way of the groundwater pathway near Lemont, Illinois

Invasive species such as Asian carps have the potential to travel in the egg, larval, or fry stages from the Des Plaines River (DPR) to the Chicago Sanitary and Ship Canal (CSSC) by way of the network of secondary-permeability features in the dolomite aquifer between these water bodies. Such movement would circumvent the electric fish barrier on the canal and allow Asian carps to travel unimpeded into Lake Michigan. This potential pathway for the spread of Asian carps and other invasive species was evaluated by the U.S. Geological Survey. The bed of the DPR appears to be in at least partial contact with the exposed bedrock in most of the area from about 1 mile west of Kingery Highway to Romeo Road (the study area). Areas of exposed bedrock are the most likely places for Asian carps to enter the groundwater system from the DPR. Water levels in the DPR typically are about 7–16 feet higher than those in the CSSC in most of the study area. This difference in water level provides the driving force for the potential spread of Asian carps from the DPR to the CSSC by way of groundwater. Groundwater flow (and potentially invasive-species movement) is through an interconnected network of permeable vertical and horizontal fractures within the Silurian dolomite bedrock. At least some of the fractures are associated with paleo-karst features. Several investigative techniques identified horizontal permeable fractures at about 546–552 feet above the North American Vertical Datum of 1988 within about 55 feet of the CSSC in the focus area between Lemont Road and Interstate 355. The elevation of the bottom of the CSSC in this area is about 551 feet, indicating that a direct conduit for flow of groundwater to the CSSC may be present. Wells further away from the CSSC in this area do not intercept fractures, so the fracture network may not be continuous between the DPR and the CSSC. These data are consistent with field observations of the secondary-permeability network along the CSSC walls, which indicate that the secondary-permeability features are completely filled with Pennsylvanian sediments within a few feet of the canal wall. Water-level data indicate the potential for flow from the DPR into the Silurian aquifer in the focus area, then from the aquifer to the CSSC. Water-level data also indicate that the fractures within the aquifer in the focus area are hydraulically well connected to the CSSC but not to the DPR, indicating that flow from the DPR to the groundwater system may not be substantial or rapid. Water-quality data in the CSSC and the DPR show similar values and trends and are affected by diel and longer term variations in climate and precipitation. However, the values and trends in water quality in the groundwater system tended to be substantially different from those in the DPR and the CSSC, indicating that the DPR and the CSSC do not appreciably recharge the groundwater system. Water-quality and flow data do indicate that groundwater discharges to the CSSC in part of the focus area. The absence of substantial hydraulic interaction between the groundwater and the DPR is supported by the absence of detectable concentrations of the dye tracer added to the DPR in groundwater in the focus area, which indicates that water from the DPR requires more than 2 weeks to move into the monitored parts of the groundwater system under approximately typical hydraulic conditions. The totality of the data indicates that there is minimal potential for the inter-basin spread of Asian carps by way of the groundwater pathway between Romeo Road and Stickney, Illinois.

Illinois↗
USGS2005

Effects of decreased ground-water withdrawal on ground-water levels and chloride concentrations in Camden County, Georgia, and ground-water levels in Nassau County, Florida, from September 2001 to May 2003

During October 2002, the Durango Paper Company formerly Gillman Paper Company) in St. Marys, Georgia, shut down paper-mill operations; the shutdown resulted in decreased ground-water withdrawal in Camden County by 35.6 million gallons per day. The decrease in withdrawal resulted in water-level rise in wells completed in the Floridan aquifer system and the overlying surficial and Brunswick aquifer systems; many wells in the St. Marys area flowed for the first time since the mill began operations during 1941. Pumping at the mill resulted in the development of a cone of depression that coalesced with a larger adjacent cone of depression at Fernandina Beach, Florida. Since closure of the mill, the cone at St. Marys is no longer present, although the cone still exists at Fernandina Beach, Florida. Historical water-level data from the production wells at the mill indicate that the pumping water level ranged from 68 to 235 feet (ft) below North American Vertical Datum of 1988 (NAVD 88) and averaged about 114 ft when the mill was operating. Since the shutdown, it is estimated that water levels at the mill have risen about 140 ft and are now at about 30 ft above NAVD 88. The water-level rise in wells in outlying areas in Camden County was less pronounced and ranged from about 5 to 10 ft above NAVD 88. Because of the regional upward water-level trend in the Upper Floridan aquifer that started during 19992000 in most of the coastal area, combined with a steeper upward trend beginning during October 2002, it was not possible to determine if the 510 ft rise in water levels in wells away from St. Marys was due to the mill closure. In addition to water-level rise of 2226 ft in the Floridan aquifer system, water-level rises in the overlying surficial and Brunswick aquifer systems at St. Marys after the shutdown indicate upward leakage of water. Water levels had stabilized in the confined surficial and Upper and Lower Floridan aquifers by AprilMay 2003; however, the water level in the upper Brunswick aquifer was still rising as of May 2003. Chloride concentrations in the Upper Floridan aquifer in Camden County do not exceed the State and Federal drinking-water standard of 250 milligrams per liter (mg/L). With the exception of three wells located at St. Marys, all of the wells sampled during this study (from September 2002 to May 2003) had chloride concentrations ranging from 30 to 50 mg/L, which are considered within background levels for the Upper Floridan aquifer in this area. The three wellstwo at the Durango Paper Company and the other an old unused City of St. Marys wellhad chloride concentrations that ranged from 74 to 175 mg/L, which are above the background level, but were still below the 250-mg/L drinking-water standard. The source has not been determined for the elevated chloride concentration in these wells; the chloride concentration in one of the wells has decreased slightly since the paper-mill shutdown. Chloride concentrations throughout Camden County showed little change after the paper-mill shutdown.

Florida, Georgia↗
USGS2017

Flood-inundation maps for the Meramec River at Valley Park and at Fenton, Missouri, 2017

Two sets of digital flood-inundation map libraries that spanned a combined 16.7-mile reach of the Meramec River that extends upstream from Valley Park, Missouri, to downstream from Fenton, Mo., were created by the U.S. Geological Survey (USGS) in cooperation with the U.S. Army Corps of Engineers, St. Louis Metropolitan Sewer District, Missouri Department of Transportation, Missouri American Water, and Federal Emergency Management Agency Region 7. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science website at https://water.usgs.gov/osw/flood_inundation/ , depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the cooperative USGS streamgages on the Meramec River at Valley Park, Mo., (USGS station number 07019130) and the Meramec River at Fenton, Mo. (USGS station number 07019210). Near-real-time stage data at these streamgages may be obtained from the USGS National Water Information System at https://waterdata.usgs.gov/nwis or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at http:/water.weather.gov/ahps/ , which also forecasts flood hydrographs at these sites (listed as NWS sites vllm7 and fnnm7, respectively). Flood profiles were computed for the stream reaches by means of a calibrated one-dimensional step-backwater hydraulic model. The model was calibrated using a stage-discharge relation at the Meramec River near Eureka streamgage (USGS station number 07019000) and documented high-water marks from the flood of December 2015 through January 2016. The calibrated hydraulic model was used to compute two sets of water-surface profiles: one set for the streamgage at Valley Park, Mo. (USGS station number 07019130), and one set for the USGS streamgage on the Meramec River at Fenton, Mo. (USGS station number 07019210). The water-surface profiles were produced for stages at 1-foot (ft) intervals referenced to the datum from each streamgage and ranging from the NWS action stage, or near bankfull discharge, to the stage corresponding to the estimated 0.2-percent annual exceedance probability (500-year recurrence interval) flood, as determined at the Eureka streamgage (USGS station number 07019000). The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from light detection and ranging data having a 0.28-ft vertical accuracy and 3.28-ft horizontal resolution) to delineate the area flooded at each flood stage (water level). The availability of these maps, along with internet information regarding current stage from the USGS streamgages and forecasted high-flow stages from the NWS, will provide emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures and for postflood recovery efforts.

Missouri↗
USGS2010

Water-level altitudes 2010 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2009 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Most of the subsidence in the Houston-Galveston region has occurred as a direct result of groundwater withdrawals for municipal supply, industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers causing compaction of the clay layers of the aquifer sediments. This report, prepared by the U.S. Geological Survey, in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, and Lone Star Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains maps showing 2010 water-level altitudes for the Chicot, Evangeline, and Jasper aquifers, respectively; maps showing 1-year (2009-10) water-level-altitude changes for each aquifer; maps showing 5-year (2005-10) water-level-altitude changes for each aquifer; maps showing long-term (1990-2010 and 1977-2010) water-level-altitude changes for the Chicot and Evangeline aquifers; a map showing long-term (2000-10) water-level-altitude change for the Jasper aquifer; a map showing locations of borehole extensometer sites; and graphs showing measured compaction of subsurface material at the extensometers from 1973, or later, through 2009. Tables listing the data used to construct each aquifer-data map and the compaction graphs are included. Water levels in the Chicot, Evangeline, and Jasper aquifers were measured during December 2009-March 2010. In 2010, water-level-altitude contours for the Chicot aquifer ranged from 200 feet below National Geodetic Vertical Datum of 1929 or North American Vertical Datum of 1988 (hereinafter, datum) in a small area in southwestern Harris County to 200 feet above datum in central to southwestern Montgomery County. Water-level-altitude changes in the Chicot aquifer ranged from a 49-foot decline to a 67-foot rise (2009-10), from a 25-foot decline to a 35-foot rise (2005-10), from a 40-foot decline to an 80-foot rise (1990-2010), and from a 140-foot decline to a 200-foot rise (1977-2010). In 2010, water-level-altitude contours for the Evangeline aquifer ranged from 300 feet below datum in north-central Harris County to 200 feet above datum at the boundary of Waller, Montgomery, and Grimes Counties. Water-level-altitude changes in the Evangeline aquifer ranged from a 58-foot decline to a 69-foot rise (2009-10), from an 80-foot decline to an 80-foot rise (2005-10), from a 200-foot decline to a 220-foot rise (1990-2010), and from a 320-foot decline to a 220-foot rise (1977-2010). In 2010, water-level-altitude contours for the Jasper aquifer ranged from 200 feet below datum in south-central Montgomery County to 250 feet above datum in eastern-central Grimes County. Water-level-altitude changes in the Jasper aquifer ranged from a 39-foot decline to a 39-foot rise (2009-10), from a 110-foot decline to no change (2005-10), and from a 180-foot decline to no change (2000-10). Compaction of subsurface materials (mostly in the clay layers) composing the Chicot and Evangeline aquifers was recorded continuously at 13 borehole extensometers at 11 sites. For the period of record beginning in 1973, or later, and ending in December 2009, cumulative clay compaction data measured by 12 extensometers ranged from 0.088 foot at the Texas City-Moses Lake site to 3.559 foot at the Addicks site. The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface materials. Therefore, it is not possible to extrapolate or infer a rate of clay compaction for an area based on the rate of compaction measured at a nearby extensometer.

Texas↗
USGS2011

Water-level altitudes 2011 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2010 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Most of the subsidence in the Houston–Galveston region has occurred as a direct result of groundwater withdrawals for municipal supply, industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers causing compaction of the clay layers of the aquifer sediments. This report, prepared by the U.S. Geological Survey, in cooperation with the Harris–Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, and Lone Star Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction in the Chicot and Evangeline aquifers in the Houston–Galveston region. The report contains maps showing 2011 water-level altitudes for the Chicot, Evangeline, and Jasper aquifers; maps showing 1-year (2010–11) water-level-altitude changes for each aquifer; maps showing 5-year (2006–11) water-level-altitude changes for each aquifer; maps showing long-term (1990–2011 and 1977–2011) water-level-altitude changes for the Chicot and Evangeline aquifers; a map showing long-term (2000–11) water-level-altitude change for the Jasper aquifer; a map showing locations of borehole extensometer sites; and graphs showing measured compaction of subsurface material at the extensometers from 1973, or later, through 2010. Tables listing the data used to construct each aquifer-data map and the compaction graphs are included. Water levels in the Chicot, Evangeline, and Jasper aquifers were measured during December 2010–February 2011. In 2011, water-level-altitude contours for the Chicot aquifer ranged from 200 feet below North American Vertical Datum of 1988 (hereinafter, datum) in a small area in southwestern Harris County to 200 feet above datum in central to southwestern Montgomery County. Water-level-altitude changes in the Chicot aquifer ranged from a 40-foot decline to a 33-foot rise (2010–11), from a 10-foot decline to an 80-foot rise (2006–11), from a 140-foot decline to a 100-foot rise (1990–2011), and from a 120-foot decline to a 200-foot rise (1977–2011). In 2011, water-level-altitude contours for the Evangeline aquifer ranged from 300 feet below datum in north-central Harris County to 200 feet above datum at the boundary of Waller, Montgomery, and Grimes Counties. Water-level-altitude changes in the Evangeline aquifer ranged from a 43-foot decline to a 73-foot rise (2010–11), from a 40-foot decline to a 160-foot rise (2006–11), from a 200-foot decline to a 240-foot rise (1990–2011), and from a 340-foot decline to a 260-foot rise (1977–2011). In 2011, water-level-altitude contours for the Jasper aquifer ranged from 200 feet below datum in south-central Montgomery County to 250 feet above datum in east-central Grimes County. Water-level-altitude changes in the Jasper aquifer ranged from a 45-foot decline to a 29-foot rise (2010–11), from a 90-foot decline to a 10-foot rise (2006–11), and from a 190-foot decline to no change (2000–11). Compaction of subsurface materials (mostly in the clay layers) composing the Chicot and Evangeline aquifers was recorded continuously at 13 borehole extensometers at 11 sites. For the period of record beginning in 1973, or later, and ending in December 2010, cumulative clay compaction data measured by 12 extensometers ranged from 0.100 foot at the Texas City–Moses Lake site to 3.544 foot at the Addicks site. The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface materials. Therefore, it is not possible to extrapolate or infer a rate of clay compaction for an area based on the rate of compaction measured at a nearby extensometer.

Texas↗
USGS2017

U.S. Geological Survey Karst Interest Group Proceedings, San Antonio, Texas, May 16–18, 2017

Introduction and Acknowledgments Karst aquifer systems are present throughout parts of the United States and some of its territories, and have developed in carbonate rocks (primarily limestone and dolomite) and evaporites (gypsum, anhydrite, and halite) that span an interval of time encompassing more than 550 million years. The depositional environments, diagenetic processes, post-depositional tectonic events, and geochemical weathering processes that form karst aquifers are varied and complex. These factors involve biological, chemical, and physical changes that when combined with the diverse climatic regimes in which karst development has taken place, result in the unique dual- or triple-porosity nature of karst aquifers. These complex hydrogeologic systems typically represent challenging and unique conditions to scientists attempting to study groundwater flow and contaminant transport in these terrains. The dissolution of carbonate rocks and the subsequent development of distinct and beautiful landscapes, caverns, and springs have resulted in the most exceptional karst areas being designated as national or state parks. Tens of thousands of similar areas in the United States have been developed into commercial caverns and known privately owned caves. Both public and private properties provide access for scientists to study the flow of groundwater in situ . Likewise, the range and complexity of landforms and groundwater flow systems associated with karst terrains are enormous, perhaps more than for any other aquifer type. Karst aquifers and landscapes that form in tropical areas, such as the cockpit karst along the north coast of Puerto Rico, differ greatly from karst landforms in more arid climates, such as the Edwards Plateau in west-central Texas or the Guadalupe Mountains near Carlsbad, New Mexico, where hypogenic processes have played a major role in speleogenesis. Many of these public and private lands also contain unique flora and fauna associated with these karst hydrogeologic systems. As a result, numerous federal, state, and local agencies have a strong interest in the study of karst terrains. Many of the major springs and aquifers in the United States have developed in carbonate rocks, such as the Floridan aquifer system in Florida and parts of Alabama, Georgia, and South Carolina; the Ozark Plateaus aquifer system in parts of Arkansas, Kansas, Missouri, and Oklahoma; and the Edwards-Trinity aquifer system in west-central Texas. These aquifers, and the springs that discharge from them, serve as major water-supply sources and form unique ecological habitats. Competition for the water resources of karst aquifers is common, and urban development and the lack of attenuation of contaminants in karst areas due to dissolution features that form direct pathways into karst aquifers can impact the ecosystem and water quality associated with these aquifers. The concept for developing a platform for interaction among scientists within the U.S. Geological Survey (USGS) working on karst-related studies evolved from the November 1999 National Groundwater Meeting of the USGS. As a result, the Karst Interest Group (KIG) was formed in 2000. The KIG is a loose-knit, grass-roots organization of USGS and non-USGS scientists and researchers devoted to fostering better communication among scientists working on, or interested in, karst science. The primary mission of the KIG is to encourage and support interdisciplinary collaboration and technology transfer among scientists working in karst areas. Additionally, the KIG encourages collaborative studies between the different mission areas of the USGS as well as with other federal and state agencies, and with researchers from academia and institutes. To accomplish its mission, the KIG has organized a series of workshops that have been held near nationally important karst areas. To date (2017) seven KIG workshops, including the workshop documented in this report, have been held. The workshops typically include oral and poster sessions on selected karst-related topics and research, as well as field trips to local karst areas. To increase non-USGS participation an effort was made for the workshops to be held at a university or institute beginning with the fourth workshop. Proceedings of the workshops are published by the USGS and are available online at the USGS publications warehouse https://pubs.er.usgs.gov/ by using the search term “karst interest group.” The first KIG workshop was held in St. Petersburg, Florida, in 2001, in the vicinity of the large springs and other karst features of the Floridan aquifer system. The second KIG workshop was held in 2002, in Shepherdstown, West Virginia, in proximity to the carbonate aquifers of the northern Shenandoah Valley, and highlighted an invited presentation on karst literature by the late Barry F. Beck of P.E. LaMoreaux and Associates. The third KIG workshop was held in 2005, in Rapid City, South Dakota, near evaporite karst features in limestones of the Madison Group in the Black Hills of South Dakota. The Rapid City KIG workshop included field trips to Wind Cave National Park and Jewel Cave National Monument, and featured a presentation by Thomas Casadevall, then USGS Central Region Director, on the status of Earth science at the USGS. The fourth KIG workshop in 2008 was hosted by the Hoffman Environmental Research Institute and Center for Cave and Karst Studies at Western Kentucky University in Bowling Green, Kentucky, near Mammoth Cave National Park and karst features of the Chester Upland and Pennyroyal Plateau. The workshop featured a late-night field trip into Mammoth Cave led by Rickard Toomey and Rick Olsen, National Park Service. The fifth KIG workshop in 2011 was a joint meeting of the USGS KIG and University of Arkansas HydroDays, hosted by the Department of Geosciences at the University of Arkansas in Fayetteville. The workshop featured an outstanding field trip to the unique karst terrain along the Buffalo National River in the southern Ozarks, and a keynote presentation on paleokarst in the United States was delivered by Art and Peggy Palmer. The sixth KIG workshop was hosted by the National Cave and Karst Research Institute (NCKRI) in 2014, in Carlsbad, New Mexico. George Veni, Director of the NCKRI, served as a co-chair of the workshop with Eve Kuniansky of the USGS. The workshop featured speaker Dr. Penelope Boston, Director of Cave and Karst Studies at New Mexico Tech, Socorro, and Academic Director at the NCKRI, who addressed the future of karst research. The field trip on evaporite karst of the lower Pecos Valley was led by Lewis Land (NCKRI karst hydrologist), and the field trip on the geology of Carlsbad Caverns National Park was led by George Veni. This current seventh KIG workshop is being held in San Antonio at the University of Texas at San Antonio (UTSA). This 2017 workshop is being hosted by the Department of Geological Sciences’ Student Geological Society (SGS), and student chapters of the American Association of Petroleum Geologists (AAPG) and Association of Engineering Geologists (AEG), with support by the UTSA Department of Geological Sciences and Center for Water Research. The UTSA student chapter presidents, Jose Silvestre (SGS), John Cooper (AAPG), and Tyler Mead (AEG) serve as co-chairs of the 2017 workshop with Eve Kuniansky of the USGS. The technical session committee is chaired by Eve Kuniansky, USGS, and includes Michael Bradley, Tom Byl, Rebecca Lambert, John Lane, and James Kaufmann, all USGS, and Patrick Tucci, retired USGS. The logistics committee includes Amy Clark, Yongli Gao, and Lance Lambert (Department Chair), UTSA Department of Geological Sciences; and Ryan Banta and Allan Clark, USGS, San Antonio, Texas. The field trip committee is chaired by Allan Clark and includes Amy Clark, Yongli Gao, and Keith Muehlestein, UTSA; Marcus Gary, Edwards Aquifer Authority and University of Texas at Austin; Ron Green, Southwest Research Institute; Geary Schindel, Edwards Aquifer Authority; and George Veni, NCKRI. Additionally, two organizations have assisted the UTSA student chapters in hosting the meeting by donating funds to the chapters: the Edwards Aquifer Authority, San Antonio, Texas, and the Barton Springs Edwards Aquifer Authority, Austin, Texas. Additionally, Yongli Gao, Center for Water Research and Department of Geological Sciences, UTSA, helped develop sessions on cave and karst research in China for this workshop. These proceedings could not have been accomplished without the assistance of Lawrence E. Spangler as co-editor who not only has subject matter expertise, but also serves as an editor with the USGS Science Publishing Network. We sincerely hope that this workshop continues to promote future collaboration among scientists of varied and diverse backgrounds, and improves our understanding of karst aquifer systems in the United States and its territories. The extended abstracts of USGS authors were peer reviewed and approved for publication by the USGS. Articles submitted by university researchers and other federal and state agencies did not go through the formal USGS peer review and approval process, and therefore may not adhere to USGS editorial standards or stratigraphic nomenclature. However, all articles had a minimum of two peer reviews and were edited for consistency of appearance in the proceedings. The use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The USGS Water Availability and Use Science Program funded the publication costs of the proceedings.

Scientific Investigations Report↗
USGS2006

Geologic map of the Yacolt quadrangle, Clark County, Washington

The Yacolt 7.5' quadrangle is situated in the foothills of the western Cascade Range of southwestern Washington approximately 35 km northeast of Portland, Oregon. Since late Eocene time, the Cascade Range has been the locus of an active volcanic arc associated with underthrusting of oceanic lithosphere beneath the North American continent along the Cascadia Subduction Zone. Volcanic and shallow-level intrusive rocks emplaced early in the history of the arc underlie most of the Yacolt quadrangle, forming a dissected and partly glaciated terrain with elevations between 250 and 2180 ft (75 and 665 m). The bedrock surface slopes irregularly but steeply to the southwest, forming the eastern margin of the Portland Basin, and weakly consolidated Miocene and younger basin-fill sediments lap up against the bedrock terrain in the southern part of the map area. A deep canyon, carved by the East Fork Lewis River that flows westward out of the Cascade Range, separates Yacolt and Bells Mountains, the two highest points in the quadrangle. Just west of the quadrangle, the river departs from its narrow bedrock channel and enters a wide alluvial floodplain. Bedrock of the Yacolt quadrangle consists of near-horizontal strata of Oligocene volcanic and volcaniclastic rocks that comprise early products of the Cascade volcanic arc. Basalt and basaltic andesite flows predominate. Most were emplaced on the flanks of a large mafic shield volcano and are interfingered with crudely bedded sections of volcanic breccia of probable lahar origin and a variety of well bedded epiclastic sedimentary rocks. At Yacolt Mountain, the volcanogenic rocks are intruded by a body of Miocene quartz diorite that is compositionally distinct from any volcanic rocks in the map area. The town of Yacolt sits in a north-northwest-trending valley apparently formed within a major fault zone. Several times during the Pleistocene, mountain glaciers moved down the Lewis River valley and spread southward into the map area. The largest glacier(s) covered the entire map area north of the East Fork Lewis River except for the summit of Yacolt Mountain. As the ice receded, it left behind a sculpted bedrock topography thickly mantled by drift, and deposited outwash in the fault-bounded valley at Yacolt and along the East Fork Lewis River valley. This map is a contribution to a program designed to improve geologic knowledge of the Portland Basin region of the Pacific Northwest urban corridor, the densely populated Cascadia forearc region of western Washington and Oregon. More detailed information on the bedrock and surficial geology of the basin and its surrounding area is necessary to refine assessments of seismic risk, ground-failure hazards and resource availability in this rapidly growing region.

Scientific Investigations Map↗
USGS2007

Survey of chemical contaminants in the Hanalei River, Kaua'i, Hawai'i, 2001

The Hanalei River on the island of Kaua'i in Hawai'i was designated an American Heritage River in 1998, providing special attention to natural resource protection, economic revitalization, and historic and cultural preservation. Agricultural, urban, and tourism-related activities are potential sources of contamination within the Hanalei River watershed. The objective of this study was to measure certain persistent organic chemicals and elements in the Hanalei River. During a relatively low-flow period in December of 2001, samples of native Akupa sleeper fish ( Eleotris sandwicensis ), freshwater Asian clam ( Corbicula fluminea ), giant mud crab ( Scylla serrata ), surface water, and stream bed sediment were collected from a lower estuarine reach of the river near its mouth at Hanalei Bay and from an upper reach at the Hanalei National Wildlife Refuge. Samples were analyzed for residues of urban and agricultural chemicals including organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and elements (including mercury, lead, cadmium, arsenic, and selenium). Organic contaminants were extracted from the samples with solvent, enriched, and then analyzed by gas chromatographic analysis with electron capture or mass spectrometric detection. Samples were acid-digested for semi-quantitative analysis for elements by inductively-coupled plasma-mass spectrometry and for quantitative analysis by atomic absorption spectrophotometry. Concentrations of organochlorine pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls in biota, surface water, and bed sediment sampled from the Hanalei River ranged from nondetectable to very low levels. Polychlorinated biphenyls were below detection in all samples. Dieldrin, the only compound detected in the water samples, was present at very low concentrations of 1-2 nanograms per liter. Akupa sleeper fish and giant mud crabs from the lower reach ranged from 1 to 5 nanograms per gram (wet weight) dieldrin and from less than 0.3 to 2.1 nanograms per gram total chlordane. Concentrations of individual polycyclic aromatic hydrocarbons in the lower reach bed sediments ranged from less than 1 to 190 nanograms per gram (dry weight). Relative concentrations (patterns) of the polycyclic aromatic hydrocarbons in one portion of a sediment sample indicated combustion sources. Concentrations of elements in the surface water, biota, and sediment samples were below toxicity thresholds of ecological concern. In summary, concentrations of the organic contaminants and elements targeted by this study of the Hanalei River in 2001 were below U.S. Environmental Protection Agency probable adverse effects levels for aquatic organisms.

Scientific Investigations Report↗
USGS2024

Spatial distribution of API gravity and gas/oil ratios for petroleum accumulations in Upper Cretaceous strata of the San Miguel, Olmos, and Escondido Formations of the south Texas Maverick Basin—Implications for petroleum migration and charge history

The Maverick Basin of south Texas is currently undergoing active exploration and production of gas and oil from tight sandstone reservoirs. The most productive tight sandstones in the basin are in the Upper Cretaceous San Miguel, Olmos, and Escondido Formations. These units are second only to the Eagle Ford Shale in terms of cumulative production volumes. The structural history of the Maverick Basin, from rifting to subsidence to exhumation, has had a profound effect on the characteristics of these reservoirs and the petroleum resources contained therein. This U.S. Geological Survey review of the production history of these strata reflects a recent shift from conventional production to horizontal drilling (unconventional) that exploits low permeability reservoirs in previously overlooked areas of existing oil and gas fields in southern Texas, typically outside of established field boundaries. To investigate the physical properties of the Maverick Basin hydrocarbon accumulations, this case study compiled American Petroleum Institute (API) gravity measurements and calculated cumulative gas/oil ratios (GOR) for thousands of producing wells from the San Miguel, Olmos, and Escondido Formations. Maps were generated from the compiled well production data to show the spatial heterogeneity of API gravity and GOR values for the three formations within the Maverick Basin and immediately outside the basin to the northeast. Within the Maverick Basin, the spatial patterns of API gravity values indicate lighter oils downdip towards the southern basin edge. GOR values indicative of wet and dry gases within the basin are seen interspersed, with values that correspond to black and heavy oils. Differences in the spatial patterns of the petroleum properties within the Maverick Basin are interpreted as effects of Eocene basin inversion caused by Laramide orogenic deformation, and the resulting reservoir exhumation of basin strata. East of the Maverick Basin, spatial distributions of API gravity and GOR values show progressively heavier oils updip to the northwest, grading to dry gases downdip to the southeast, which correlates to the oil and gas windows of the underlying Eagle Ford Shale. Correlation of API gravity and GOR values from the San Miguel, Olmos, and Escondido Formations with thermal maturity data from the Eagle Ford Shale suggests that the Eagle Ford Shale is the petroleum source, and that petroleum migration was approximately vertical for areas to the east of the Maverick Basin. The discontinuity of API gravity and GOR properties within the Maverick Basin implies a complex petroleum charge history, possibly involving the remigration of petroleum and the addition of petroleum from other source intervals in Mexico, to the southwest. Depressurization of exhumed, overpressured reservoirs of the San Miguel, Olmos, and Escondido Formations can explain the intermittent occurrence of gas production throughout the southern Maverick Basin by exsolution of gas from formation brines and the resulting dry gas flushing of hydrocarbon-charged reservoirs. The introduction of dry gas through flushing can, in turn, explain why the patterns of API gravity and GOR values are so dissimilar in the Maverick Basin. This process has implications for possible future production of unconventional resources from undiscovered tight-gas reservoirs in strata of the San Miguel, Olmos, and Escondido Formations, and a different approach to petroleum exploration may be needed in the Maverick Basin relative to exploration techniques applied in other basins within the northern Gulf of Mexico.

Texas↗
USGS2024

Status of water-level altitudes and long-term and short-term water-level changes in the Chicot and Evangeline (undifferentiated) and Jasper aquifers, greater Houston area, Texas, 2023

Since the early 1900s, groundwater withdrawn from the primary aquifers that compose the Gulf Coast aquifer system—the Chicot, Evangeline, and Jasper aquifers—has been an important source of water in the greater Houston area, Texas. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting the status of water-level altitudes and water-level changes in these aquifers in the greater Houston area. In this report, the Chicot and Evangeline aquifers are treated as a single aquifer for the purposes of providing annual assessments of regional-scale water-level altitudes and water-level changes over time. In 2023, shaded depictions of water-level altitudes for the Chicot and Evangeline aquifers (undifferentiated) ranged from about 286 feet (ft) below the North American Vertical Datum of 1988 (NAVD 88) to about 169 ft above NAVD 88. The largest decline in water-level altitudes indicated by the 1977–2023 long-term water-level-change map was in south-central Montgomery County southeast of The Woodlands. In comparison, the 1990–2023 long-term water-level-change map depicts the largest declines in water-level altitudes in localized areas at or near certain wells in parts of northwestern Harris County and south-central Montgomery County. The largest rise in water-level altitudes for 1977–2023 is depicted in a relatively large area in southeastern Harris County, whereas the largest rise in water-level altitudes for 1990–2023 is depicted in a relatively large area in central Harris County. The 5-year short-term water-level-change map depicts the largest declines at three wells in northern Fort Bend County, one well in western Harris County, and three wells in south-central Montgomery County and the largest rise at one well in central Harris County. The 1-year short-term water-level-change map depicts the largest declines at one well in northern Fort Bend County and two wells in southwestern Harris County and the largest rises at one well in northern Brazoria County and one well in south-central Montgomery County. In 2023, shaded depictions of water-level altitudes for the Jasper aquifer ranged from about 242 ft below NAVD 88 to about 218 ft above NAVD 88. The 2000–23 long-term water-level-change map depicts water-level declines throughout the study area where water-level-measurement data from the aquifer were collected, with the largest declines in north-central Harris County and south-central Montgomery County south of The Woodlands. The 5-year short-term water-level-change map depicts the largest declines at two wells in central Montgomery County near Conroe and two wells in south-central Montgomery County southeast of The Woodlands and the largest rise at one well in western Montgomery County. The 1-year short-term water-level-change map depicts the largest declines at four wells in south-central Montgomery County southeast of The Woodlands and one well in central Montgomery County near Conroe and the largest rises at two wells in western Montgomery County.

Texas↗
USGS2004

Status assessment and conservation plan for the yellow-billed loon (Gavia adamsii)

Because of its restricted range, small population size, specific habitat requirements, and perceived threats to its breeding habitat, the Yellow-billed Loon (Gavia adamsii) is a species of conservation concern to the U.S. Fish and Wildlife Service and the subject of a petition for listing under the Endangered Species Act. This Status Assessment synthesizes current information on population size, trends, and potential threats to Yellow-billed Loons, and the Conservation Plan identifies research and monitoring activities that would contribute to the conservation of this species. The preparation of this report was requested and funded by the U.S. Fish and Wildlife Service, Nongame Bird Office, Region 7.The Status Assessment and Conservation Plan for the Yellow-billed Loon can be summarized as follows:? Northern Alaska breeding grounds support an average of 3,369 individuals, including <1,000 nesting pairs in most years. The Yellow-billed Loon ranks as one of the 10 rarest birds that breeds regularly within the main land U.S. and one of only 20 with a North American population <16,000 individuals (Section 6-E).? There is no evidence of a long-term trend in the Yellow-billed Loon population index since 1986 (-0.9% annual change), but interpretation of surveys is complicated by changes in observers and high annual variation, and the 95% confidence interval is large (-3.6% to +1.8% annual change). The low reproductive potential of Yellow-billed Loons suggests that recovery from a substantial decline would not occur rapidly. There are no systematic surveys of Canadian and Russian breeding populations (Section 6-F).? The expansion of the oil industry into prime Yellow-billed Loon breeding habitat is a recent occurrence and we lack the necessary information to accurately predict its effect on the population. Most of northern Alaska?s Yellow-billed Loons (91%) occur on the National Petroleum Reserve?Alaska, virtually all of which is open or proposed to be opened to development and where there is no permanent or legal protection of Yellow-billed Loon habitat (Section 7-A).? Other potential factors affecting the population are also addressed, such as contaminants, subsistence hunting, by catch in subsistence and commercial fisheries on the breeding and wintering grounds, and health of the marine ecosystem off the coast of East Asia where Alaska?s Yellow-billed Loons winter, but data are lacking to reach strong conclusions on most issues.? The conservation goal adopted by the Alaska Loon and Grebe Working Group for the Yellow-billed Loon is to maintain a stable breeding population, of current size and distribution, across the extent of the loon?s breeding range in Alaska. The Conservation Plan, designed to provide information necessary to meet this goal, puts forth seven objectives: 1) Conduct annual population surveys having negligible bias and 80% statistical power to detect a 3.4% annual decline, a decline that would result in a 50% loss of the population within 20 years; 2) Obtain an unbiased and reliable estimate of the size of Alaska?s breeding population; 3) Identify geographic regions and habitats of importance during breeding, staging, and wintering periods; 4) Use demographic models to evaluate risks to the population; 5) Identify potential effects of oil development on the breeding grounds and measures necessary to minimize the effects; 6) Evaluate the magnitude of subsistence harvest and by catch and their potential effects on the population; 7) Develop a continent-wide and range-wide context for Alaska?s population and habitat objectives.

Scientific Investigations Report↗
USGS2018

Public views of wetlands and waterfowl conservation in the United States—Results of a survey to inform the 2018 update of the North American Waterfowl Management Plan

Executive Summary This report provides information from a general public survey conducted in early 2017 to help inform the North American Waterfowl Management Plan (NAWMP) 2018 update. This report is intended for use by the NAWMP advisory committees and anyone interested in the human dimensions of wetlands and waterfowl management. A mail-out survey was sent to 5,000 addresses in the United States, which were selected randomly in proportion to the population of each State. A total of 1,030 completed surveys representing 49 States were returned, resulting in a 23 percent overall response rate. When comparing the demographics of the respondents to the U.S. census data, this sample overrepresented people who are male, older, highly educated, and white. Data were weighted on gender and age to make the results more representative of the overall U.S. population. Additionally, this sample had higher participation rates in all wildlife-related recreation activities than has been found in previous studies; this indicates there may have been selection bias, with people interested in nature-related topics more likely to complete the survey. Therefore, results likely represent a segment of the U.S. public that is more oriented toward and aware of wildlife and conservation issues than the general public as a whole. Because of this bias, responses for each question were also broken down by recreationist type (hunters, anglers, wildlife viewers, and no wildlife-related recreation). Additionally, responses for each question were split by administrative flyway (Atlantic, Central, Mississippi, Pacific) and residency (urban, urban cluster, rural) to better understand the different groups. Most respondents knew of wetlands in their local area or community, and more than half had visited wetlands in the previous 12 months. Of those who had visited wetlands, the most common reasons were for walking/hiking/biking and enjoying nature/picnicking. In addition, this sample was very concerned about the reduction or loss of ecosystem services resulting from wetlands degradation or loss. A majority of respondents were somewhat or very concerned about 9 out of 10 wetlands benefits, with hunting opportunities being the only benefit the majority of people were not concerned about. People were the most concerned about clean water, clean air, and providing a home for wildlife. In contrast, people were least concerned about hunting opportunities and wetlands providing scenic places for inspiration or spiritual renewal. Communication about wetlands that focuses on habitat, clean air, and clean water may resonate with the widest variety of people. However, if communication is targeted toward wildlife-related recreationists, including more information about the recreation benefits of wetlands and emphasizing habitat benefits may be the most effective. Many people reported having participated in conservation behaviors in the last year. The most popular activity was making the yard more desirable to wildlife, with more than three-fourths of respondents participating, followed by donating money to support wildlife/habitat conservation and talking to others in their community about conservation issues. There was lower participation in conservation behavior specifically related to wetlands and waterfowl, with two-fifths of respondents voting for candidates or ballot issues to support wetlands/waterfowl conservation and one-third advocating for political action to conserve wetlands/waterfowl. In order to better understand how to reach out to the public on nature-related topics, preferences in information channels and trust in information sources were explored. Respondents were mostly likely to want to receive their information through personal experience, by reading or accessing online content, and through watching visual media online. People were least likely to want to receive information through listening to recorded audio media, attending educational opportunities, and listening to live audio media. These results emphasize the importance of having content available online in an easily accessible and appealing format. Visual media in particular seems to be preferred across a wide variety of people. Additionally, people had the highest trust in scientific organizations, universities/educational organizations, and friends/family/neighbors/colleagues. The least trusted sources were national media/news, religious organizations, and local media/news. Urban respondents had higher trust levels overall, particularly for the government. Hunters and those in rural areas had lower levels of trust in the government but higher trust in family/friends. In this sample, few respondents reported hunting waterfowl (5 percent) or hunting other game (16 percent) in the last year. Additionally, few respondents said they were very or somewhat likely to hunt waterfowl in the following 12 months. Even after considering that self-selection bias would make it more likely for hunters to respond to the survey, the relatively small number of respondents who identified as hunters reinforces that engagement of other wildlife-related recreationists is critical to meeting the third goal of the NAWMP 2012 revision—to increase numbers of wetlands/waterfowl conservationists. Many people also had negative perceptions of hunting. Half of the respondents stated that hunting would be unpleasant, and two-fifths believed hunting would be boring. In contrast, people had more favorable attitudes toward birdwatching, with only one-sixth saying it would be unpleasant and less than one-third saying it would be boring. A majority of respondents thought they could easily go hunting or birdwatching in the following 12 months. Overall, people had much more positive views toward birdwatching and expressed fewer barriers to participating in it. When asked what would prevent them from hunting, the most frequently stated reasons were moral opposition, no interest, personal health, and time constraints; for birdwatching, the most popular responses were nothing, no interest, and time constraints. These responses indicate it may be beneficial to move beyond hunting and find ways for other groups, such as birdwatchers, to play a more active role in conservation. Although not many people hunted and many people tended to have negative attitudes toward hunting, over three-fourths of people said they knew a hunter. Given that wildlife viewers, those who did not participate in wildlife-related recreation, and urban residents tended to have negative attitudes toward hunting and (or) were not interested in participating, attempting to recruit them to participate in hunting may not be effective. However, given how many people across all groups knew a hunter and the relatively high levels of trust people had in their friends/family, hunters may be effective ambassadors for promoting waterfowl and wetlands conservation among nonhunters. Additionally, because people had less preference for viewing waterfowl and other game birds compared to their preference for seeing hummingbirds and birds of prey, conservation efforts that extend beyond waterfowl and include other species that benefit from wetlands may have more appeal to a broader range of people.

Open-File Report↗