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At least 919 records · Page 51Linked to original sources
USGS2012

Estimated probability of arsenic in groundwater from bedrock aquifers in New Hampshire, 2011

Probabilities of arsenic occurrence in groundwater from bedrock aquifers at concentrations of 1, 5, and 10 micrograms per liter (µg/L) were estimated during 2011 using multivariate logistic regression. These estimates were developed for use by the New Hampshire Environmental Public Health Tracking Program. About 39 percent of New Hampshire bedrock groundwater was identified as having at least a 50 percent chance of containing an arsenic concentration greater than or equal to 1 µg/L. This compares to about 7 percent of New Hampshire bedrock groundwater having at least a 50 percent chance of containing an arsenic concentration equaling or exceeding 5 µg/L and about 5 percent of the State having at least a 50 percent chance for its bedrock groundwater to contain concentrations at or above 10 µg/L. The southeastern counties of Merrimack, Strafford, Hillsborough, and Rockingham have the greatest potential for having arsenic concentrations above 5 and 10 µg/L in bedrock groundwater. Significant predictors of arsenic in groundwater from bedrock aquifers for all three thresholds analyzed included geologic, geochemical, land use, hydrologic, topographic, and demographic factors. Among the three thresholds evaluated, there were some differences in explanatory variables, but many variables were the same. More than 250 individual predictor variables were assembled for this study and tested as potential predictor variables for the models. More than 1,700 individual measurements of arsenic concentration from a combination of public and private water-supply wells served as the dependent (or predicted) variable in the models. The statewide maps generated by the probability models are not designed to predict arsenic concentration in any single well, but they are expected to provide useful information in areas of the State that currently contain little to no data on arsenic concentration. They also may aid in resource decision making, in determining potential risk for private wells, and in ecological-level analysis of disease outcomes. The approach for modeling arsenic in groundwater could also be applied to other environmental contaminants that have potential implications for human health, such as uranium, radon, fluoride, manganese, volatile organic compounds, nitrate, and bacteria.

New Hampshire↗
USGS1987

Surface-water hydrology of the Little Black River basin, Missouri and Arkansas, before water-land improvement practices

The U. S. Department of Agriculture, Soil Conservation Service, in accordance with Public Law 566, is implementing various types of water-land improvement practices in the Little Black River basin in southeastern Missouri. These practices are designed, in part, to decrease the suspended sediment (SS) transport in the basin, decrease flood damage in the basin, and improve drainage in the agricultural area. The general features of the basin, such as geology, groundwater hydrology, soils, land use, water use, and precipitation are described; surface water quantity, quality, and suspended sediment discharge are also described. The aquifers are the Mississippi River valley alluvial aquifer, which can yield about 3,500 gal/min to properly constructed wells, and the Ozark and St. Francois aquifers, which can yield from about 30 to 500 gal/min to properly constructed wells. Soils in the area have formed in loess and cherty residuum in the uplands or have formed in alluvial sediment in the lowlands. About 93% of the estimated 3 billion gal/year of water used in the basin is for crop irrigation. The average monthly precipitation varies slightly throughout the year, with an average annual precipitation of about 47 inches. Water quality data were collected at seven stations. Specific conductance values ranged from 50 to 400 microsiemens/cm at 25 C. Water temperatures ranged from 0.0 C in the winter to 33.5 C in summer. pH values ranged from 6.4 to 8.5 units. Dissolved oxygen concentrations ranged from 2.2 to 12.8 ml/l. Total nitrogen concentrations ranged from 0.13 to 2.20 ml/l as nitrogen, with organic nitrogen as the most abundant form. Phosphorus concentrations ranged from zero to 0.29 ml/l as phosphorus. Bacterial counts were largest during storm runoff in the basin with livestock waste as the significant contributor. For the period from October 1, 1980, to September 30, 1984, the average annual SS discharge ranged from 2,230 tons/yr in the headwater areas to 27,800 tons/yr at the most downstream station. The average annual SS yield ranged from 59.6 to 85.9 tons/sq mi.

Arkansas, Missouri↗
USGS1984

U-Th-Pb, Rb-Sr, and Ar-Ar mineral and whole-rock isotopic systematics in a metamorphosed granitic terrane, southeastern California

Mesozoic structural domes are developed in an older Proterozoic crystalline basement of granitic to granodioritic foliate metaplutonic rocks in the Halloran Hills, southeastern California. Isotopic analyses of whole rocks and mineral separates from these rocks by U-Th-Pb, Rb-Sr, and Ar-Ar techniques yield a complex pattern of discordance that is the result of a fairly simple geologic history. Individual mineral isotopic systems have variably equilibrated with each other in response to Mesozoic regional metamorphism and locally to later heating during Mesozoic batholith emplacement. Discordant U-Th-Pb zircon data indicate that the granitic core rocks are 1,710 Ma and that one dioritic phase may be slightly older. Rb-Sr whole-rock model dates scatter about 1,700 Ma Rb-Sr amphibole–whole-rock and U-Th-Pb amphibole dates are also Proterozoic. Potassium feldspars retain a 207 Pb/ 206 Pb signature of their Proterozoic age. Ar-Ar amphibole spectra from the flank of the main dome reveal disturbed dates of 1,450 Ma to 1,100 Ma, and the dates become younger toward the structurally deeper core of the dome. All remaining isotopic determinations yield Mesozoic or younger dates for mineral–whole-rock systems. Rb-Sr whole-rock–apatite–feldspar–biotite analyses show nonequilibration of strontium isotopes, with resultant mineral pair dates from 4 foliate plutonic rocks ranging from 200 to 50 Ma. No single metamorphic age is indicated by the Rb-Sr data. Rb-Sr whole-rock–biotite dates are consistently younger than any other determinations and may be reduced by weathering or gain of nonradiogenic strontium from ground water. U-Pb sphene and apatite analyses from rocks that yield 1,710-Ma zircon dates are nearly concordant at 140 Ma. An amphibole from the structurally deepest rocks of the main dome that yield 140- to 150-Ma U-Pb sphene dates has an Ar-Ar plateau date of 144 Ma. The U-Pb sphene and Ar-Ar amphibole analyses are believed to be the best age estimate for the end of the highest-temperature phase of regional metamorphism. Th-Pb sphene and apatite dates and Ar-Ar biotite dates cluster at 90 ± 5 Ma as a consequence of regional cooling during Late Cretaceous time following extensive Mesozoic plutonism in the region at 97 to 90 Ma. We interpret the discordant mineral date patterns to have resulted from metamorphism of ∼1,700-Ma plutonic rocks during the Jurassic (≥ 140–50 Ma) and subsequent uplift and cooling to ∼200 °C at about 90 Ma. On the basis of this study, the isotope dating systems ranked in decreasing order of resistance to resetting are: U-Th-Pb zircon (concordia intercept) ≥ Rb-Sr whole rock ∼Rb-Sr amphibole ∼U-Th-Pb amphibole ∼Pb-Pb whole rock > Ar-Ar amphibole ≥ Rb-Sr sphene ≥ U-Pb sphene and apatite > Rb-Sr plagioclase-potassium feldspar-apatite > Th-Pb sphene and apatite ∼Ar-Ar biotite ∼U-Pb feldspars > Rb-Sr biotite.

California↗
USGS1993

Geologic studies in Alaska by the U.S. Geological Survey, 1992

This collection of 19 papers continues the annual series of U.S. Geological Survey reports on the geology of Alaska. The contributions, which include full-length Articles and shorter Geologic Notes, cover a broad range of topics including dune formation, stratigraphy, paleontology, isotopic dating, mineral resources, and tectonics. Articles, grouped under four regional headings, span nearly the entire State from the North Slope to southwestern, south-central, and southeastern Alaska (fig. 1). In the section on northern Alaska, Galloway and Carter use new data on dune morphology and radiocarbon ages from the western Arctic Coastal Plain to develop a late Holocene chronology of multiple episodes of dune stabilization and reactivation for the region. Their study has important implications for climatic changes in northern Alaska during the past 4,000 years. In two papers, Dumoulin and her coauthors describe lithofacies and conodont faunas of Carboniferous strata in the western Brooks Range, discuss depositional environments, and propose possible correlations and source areas for some of the strata. Schenk and Bird propose a preliminary division of the Lower Cretaceous stratigraphic section in the central part of the North Slope into depositional sequences. Aleinikoff and others present new U-Pb data for zircons from metaigneous rocks from the central Brooks Range. Karl and Mull, reacting to a proposal regarding terrane nomenclature for northern Alaska that was published in last year's Alaskan Studies Bulletin, provide a historical perspective of the evolution of terminology for tectonic units in the Brooks Range and present their own recommendations.

Alaska↗
USGS2016

Characterization of peak streamflows and flood inundation of selected areas in Louisiana, Texas, Arkansas, and Mississippi from flood of March 2016

Heavy rainfall occurred across Louisiana, Texas, Arkansas, and Mississippi in March 2016 as a result of a slow-moving southward dip in the jetstream, funneling tropical moisture into parts of the Gulf Coast States and the Mississippi River Valley. The storm caused major flooding in the northwestern and southeastern parts of Louisiana and in eastern Texas. Flooding also occurred in the Mississippi River Valley in Arkansas and Mississippi. Over 26 inches of rain were reported near Monroe, Louisiana, over the duration of the storm. In March 2016, U.S. Geological Survey (USGS) hydrographers made more than 500 streamflow measurements in Louisiana, Texas, Arkansas, and Mississippi. Many of those streamflow measurements were made to verify the accuracy of stage-streamflow relations at gaging stations operated by the USGS. Peak streamflows were the highest on record at 14 locations, and streamflows at 29 locations ranked in the top five for the period of record at USGS streamflow-gaging stations analyzed for this report. Following the storm, USGS hydrographers documented 451 high-water marks in Louisiana and on the western side of the Sabine River in Texas. Many of these high-water marks were used to create 19 flood-inundation maps for selected areas of Louisiana and Texas that experienced flooding in March 2016.

Arkansas, Louisiana, Mississippi, Texas↗
USGS2018

Distribution of effluent injected into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant, southeastern Florida, 1997–2011

Nonhazardous, secondarily treated, domestic wastewater (effluent) has been injected about 1 kilometer below land surface into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant in southeastern Florida. The Boulder Zone contains saline, nonpotable water. Effluent transport out of the injection zone is a risk of underground effluent injection. At the North District Wastewater Treatment Plant, injected effluent was detected outside the Boulder Zone. The U.S. Geological Survey, in cooperation with Miami-Dade Water and Sewer Department , investigated effluent transport from the Boulder Zone to overlying permeable zones in the Floridan aquifer system. One conceptual model is presented to explain the presence of effluent outside of the injection zone in which effluent injected into the Boulder Zone was transported to the Avon Park permeable zone, forced by buoyancy and injection pressure. In this conceptual model, effluent injected primarily into the Boulder Zone reaches a naturally occurring feature (a karst-collapse structure) near an injection well, through which the effluent is transported vertically upward to the uppermost major permeable zone of the Lower Floridan aquifer. The effluent is then transported laterally through the uppermost major permeable zone of the Lower Floridan aquifer to another naturally occurring feature northwest of the North District Wastewater Treatment Plant, through which it is then transported vertically upward into the Avon Park permeable zone. In addition, a leak within a monitoring well, between monitoring zones, allowed interflow between the Avon Park permeable zone and the Upper Floridan aquifer. A groundwater flow and effluent transport simulation of the hydrogeologic system at the North District Wastewater Treatment Plant, based on the hypothesized and non-unique conceptualization of the subsurface hydrogeology and flow system, generally replicated measured effluent constituent concentration trends. The model was calibrated to match observed concentration trends for total ammonium (NH 4 + ) and total dissolved solids. The investigation qualitatively indicates that fractures, karst-collapse structures, faults, or other hydrogeologic features may permit effluent injected into the Boulder Zone to be transported to overlying permeable zones in the Floridan aquifer system. These findings, however, are qualitative because the locations of transport pathways that might exist from the Boulder Zone to the Avon Park permeable zone are largely unknown.

Florida↗
USGS1996

Phosphorus dynamics in Delavan Lake Inlet, southeastern Wisconsin, 1994

Removal of rough fish from Delavan Lake Inlet in southeastern Wisconsin transformed the inlet from a shallow, turbid-water system with few macrophytes to a clear-water system with an abundance of macrophytes and increased phosphorus concentrations. To understand the changes in the phosphorus dynamics, the U.S. Geological Survey and the U.S. Army Corps of Engineers, in cooperation with the Town of Delavan, constructed a detailed phosphorus budget for the inlet for April through September 1994. The budget included inputs from the drainage basin, atmosphere, sediments (as a function of pH and the fraction of the day under anoxic conditions), and ground water. Laboratory studies estimated phosphorus flux rates under various conditions. Field studies documented ambient conditions in the inlet and fluxes of phosphorus into and out of the inlet. Phosphorus released from the sediments was estimated by coupling the flux rates, estimated in the laboratory, with ambient conditions in the inlet. The detailed phosphorus budget indicated that the increase in phosphorus concentrations was caused primarily by elevated pH resulting from increased photosynthetic activity of the macrophytes and a high release of phosphorus from the sediments. The release of phosphorus from the sediments was the largest source of phosphorus to the inlet in the spring and summer of 1994 and in other years of low to near normal runoff; however, in years of high runoff, phosphorus input from the inlet's drainage basin was the largest source of phosphorus. A less-detailed phosphorus budget constructed for the period from February 1993 to September 1994 demonstrated that, over the entire year, runoff from the drainage basin was the dominant source in the phosphorus budget. During April-September 1994, the input of phosphorus from the inlet may especially affect the summer productivity in Delavan Lake because almost 80 percent of the phosphorus loading during this time was in the form of dissolved orthophosphate.

Wisconsin↗
USGS2019

Monitoring storm tide and flooding from Hurricane Irma along the U.S. Virgin Islands, Puerto Rico, and the Southeastern United States, September 2017

Hurricane Irma skirted the northern coasts of the U.S. Virgin Islands and Puerto Rico, with maximum sustained winds of 185 miles per hour (mi/h) on September 6, 2017. The hurricane first made landfall in Florida near Cudjoe Key, in the lower Florida Keys, with maximum sustained winds of 130 mi/h on September 10, 2017. The hurricane made a second Florida landfall on Marco Island, Florida, with maximum sustained winds of 115 mi/h on September 10, 2017. The U.S. Geological Survey (USGS), in cooperation with Federal Emergency Management Agency, deployed a temporary monitoring network of water-level and barometric pressure sensors at 249 locations along the Puerto Rico, Florida, Georgia, and South Carolina coasts to record the timing, areal extent, and magnitude of hurricane storm tide and coastal flooding generated by the hurricane. Immediately following the passage of Hurricane Irma, the sensors were retrieved, and the data were disseminated on the USGS Flood Event Viewer ( https://stn.wim.usgs.gov/FEV/#IrmaSeptember2017 ). The storm-tide peak data values were verified by comparing data from hydrologic recorders and nearby high-water marks (HWMs). Following the hurricane, 508 independent HWM locations were flagged and surveyed relative to the North American Vertical Datum of 1988, National Geodetic Vertical Datum of 1929, or a local datum along the southeastern U.S. coast, and to Puerto Rico Vertical Datum of 2002 in Puerto Rico. Most HWMs were in Florida because of the path of the hurricane. The data from the Hurricane Irma storm-tide network are available on a provisional basis in tab-delimited, American Standard Code for Information Interchange (ASCII) format and Network Common Data Form (NetCDF) format by site for each sensor by using the USGS Flood Event Viewer.

Puerto Rico, U.S. Virgin Islands↗
USGS1963

Geology and ground-water resources of Hays County, Texas

The Edwards limestone of Early Cretaceous age is the chief aquifer for San Marcos Springs and about 160 other springs and wells in Hays County, along the Balcones fault zone in South-central Texas. Hays County is underlain by a basement of Paleozoic rocks; and in the southeastern part of the county the Hosston and Sligo formations of Early Cretaceous age, correlative with the Coahuila series of Mexico, have been encountered in the subsurface. Rocks exposed in the county are principally Cretaceous and Quaternary sedimentary units, which are assigned to the Trinity, Fredericksburg, and Washita groups in the Comanche series; the Eagle Ford shale, Austin chalk, Taylor marl, and Navarro group in the Gulf series: and the Leona formation and equivalent rocks in the Pleistocene series. Recent alluvium and colluvium locally overlie the older rocks. In addition to the Edwards limestone in the Fredericksburg group, waterbearing rock units in Hays County include the Pearsall formation (Travis Peak of outcrop areas) and the Glen Rose limestone in the Trinity group, the Austin chalk and Taylor marl, and the Quaternary rocks. The surface slope and regional dip are toward the southeast. Several normal strike faults have displaced the Cretaceous rocks downward to the southeast, the aggregate displacement being about 1,700 feet within the county. The boundaries of the Edwards limestone ground-water reservoir are formed by major faults which are the major controls of movement of water. Much of the water discharged at San Marcos Springs is derived from influent seepage from streams and infiltration from precipitation in recharge areas southwest of Hays County. The average underground inflow from Comal County through the Edwards limestone reservoir is estimated as 70,000 acre-feet per year for the period 1934-47. The discharge of San Marcos Springs, averaging about 55 million gallons a day during 1955, greatly exceeds local ground-water recharge within Hays County. Depth to water, direction of movement of water, subsurface location of aquifers, and quality of water in Hays County have been determined from records of 519 wells and springs, drillers' logs of 49 wells, periodic water-level measurements in about 70 wells, and chemical analyses of water samples from 238 wells and springs. Ground water from wells in the Pearsall formation generally contains less than 500 parts per million of dissolved solids. Water from the Glen Rose limestone in some places contains more than 500 parts per million of sulfate and more than 1,000 parts per million of dissolved solids; locally it is high in nitrate also. Except in the southeastern part of the county, water from the Edwards limestone is commonly very hard but is otherwise of good quality for most uses. Analyses of two water samples from the Austin chalk indicate a high content of bicarbonate. Water from the Taylor marl and from Quaternary sediments generally is hard, and locally it contains excessive nitrate. Most wells in Hays County are used for domestic and stock supplies. About 20 wells, most of them in the Edwards limestone, yield water in relatively large amounts for industrial use, irrigation, or public supplies.

Water Supply Paper↗
USGS1990

Water type and concentration of dissolved solids, chloride, and sulfate in water from the St. Francois aquifer in Missouri, Arkansas, Kansas, and Oklahoma

The St. Francois aquifer, the lowermost of three regional aquifers that form part of the Ozark Plateaus aquifer system, is composed of water-bearing sandstone and dolostone of Late Cambrian age. The aquifer was studied as part of the Central Midwest Regional Aquifer-System Analysis (CMRASA, Jorgensen and Signor, 1981), a study of regional aquifer systems in the midcontinent United States that includes parts of 10 States. Because of its significance as a source of freshwater in and adjacent to the Ozark Plateaus province (index map) of Missouri, Arkansas, Kansas, and Oklahoma, a subregional project was established to investigate the Ozark Plateaus aquifer system in more detail than the regional study could provide. The geologic and hydrologic relation between the Ozark Plateaus aquifer system and other regional aquifer systems of the Midwest is presented in Jorgensen an others (in press). The relation of the St. Francois aquifer to the Ozark Plateaus aquifer system is explained in Imes [in press (a)]. A companion publication, Imes [in press (b)], contains contour maps of the altitude of the top, thickness, and potentiometric surface of the St. Francois aquifer. This report contains maps that show water type and concentration of dissolved solids, chloride, and sulfate in water from the St. Francois aquifer. Most of the data from which these maps are compiled is stored in the CMRASA hydrochemical data base (R.B. Leonard, U.S. Geological Survey, written commun., 1986). Only water quality analyses that ionically balanced to within 10 percent are included in this report. Because few water wells are completed in the St. Francois aquifer beyond the vicinity of the St. Francois Mountains in southeastern Missouri (index map), water-quality data, with few exceptions, are limited to a relatively small area near the outcrop of the aquifer.

Hydrologic Atlas↗
USGS2000

Analytical results and sample locality map for rock, stream-sediment, and soil samples, Northern and Eastern Colorado Desert BLM Resource Area, Imperial, Riverside, and San Bernardino counties, California

In 1996-1998 the U.S. Geological Survey (USGS) conducted a geochemical study of the Bureau of Land Management’s (BLM) 5.5 million-acre Northern and Eastern Colorado Desert Resource Area (usually referred to as the NECD in this report), Imperial, Riverside, and San Bernardino Counties, southeastern California (figure 1). This study was done in support of the BLM’s Coordinated Management Plan for the area. This report presents analytical data from this study.

California↗
USGS2000

Analytical results and sample locality map for rock, stream-sediment, and soil samples, Northern and Eastern Colorado Desert BLM Resource Area, Imperial, Riverside, and San Bernardino Counties, California

In 1996-1998 the U.S. Geological Survey (USGS) conducted a geochemical study of the Bureau of Land Management's (BLM) 5.5 million-acre Northern and Eastern Colorado Desert Resource Area (usually referred to as the NECD in this report), Imperial, Riverside, and San Bernardino Counties, southeastern California (figure 1). This study was done in support of the BLM's Coordinated Management Plan for the area. This report presents analytical data from this study. To provide comprehensive coverage of the NECD, we compiled and examined all available geochemical data, in digital form, from previous studies in the area, and made sample-site plots to aid in determining where sample-site coverage and analyses were sufficient, which samples should be re-analyzed, and where additional sampling was needed. Previous investigations conducted in parts of the current study area included the National Uranium Resource Evaluation (NURE) program studies of the Needles and Salton Sea 1° x 2° quadrangles; USGS studies of 12 BLM Wilderness Study Areas (WSAs) (Big Maria Mountains, Chemehuevi Mountains, Chuckwalla Mountains, Coxcomb Mountains, Mecca Hills, Orocopia Mountains, Palen-McCoy, Picacho Peak, Riverside Mountains, Sheephole Valley (also known as Sheep Hole/Cadiz), Turtle Mountains, and Whipple Mountains); and USGS studies in the Needles and El Centro 1° x 2° quadrangles done during the early 1990s as part of a project to identify the regional geochemistry of southern California. Areas where we did new sampling of rocks and stream sediments are mainly in the Chocolate Mountain Aerial Gunnery Range and in Joshua Tree National Park, which extends into the west-central part of the NECD, as shown in figure 1 and figure 2. This report contains analytical data for 132 rock samples and 1,245 stream-sediment samples collected by the USGS, and 362 stream-sediment samples and 189 soil samples collected during the NURE program. All samples are from the Northern and Eastern Colorado Desert BLM Resource Area and vicinity. Included in the 1,245 stream-sediment samples collected by the USGS are 284 samples collected as part of the current study, 817 samples collected as part of investigations of the12 BLM WSAs and re-analyzed for the present study, 45 samples from the Needles 1° x 2° quadrangle, and 99 samples from the El Centro 1° x 2° quadrangle. The NURE stream-sediment and soil samples were re-analyzed as part of the USGS study in the Needles quadrangle. Analytical data for samples from the Chocolate Mountain Aerial Gunnery Range, which is located within the area of the NECD, were previously reported (King and Chaffee, 1999a). For completeness, these results are also included in this report. Analytical data for samples from the area of Joshua Tree National Park that is within the NECD have also been reported (King and Chaffee, 1999b). These results are not included in this report. The analytical data presented here can be used for baseline geochemical, mineral resource, and environmental geochemical studies.

California↗
USGS2015

First steps of integrated spatial modeling of titanium, zirconium, and rare earth element resources within the Coastal Plain sediments of the southeastern United States

The Coastal Plain of the southeastern United States has extensive, unconsolidated sedimentary deposits that are enriched in heavy minerals containing titanium, zirconium, and rare earth element resources. Areas favorable for exploration and development of these resources are being identified by geochemical data, which are supplemented with geological, geophysical, hydrological, and geographical data. The first steps of this analysis have been completed. The concentrations of lanthanum, yttrium, and titanium tend to decrease as distance from the Piedmont (which is the likely source of these resources) increases and are moderately correlated with airborne measurements of equivalent thorium concentration. The concentrations of lanthanum, yttrium, and titanium are relatively high in those watersheds that adjoin the Piedmont, south of the Cape Fear Arch. Although this relation suggests that the concentrations are related to the watersheds, it may be simply an independent regional trend. The concentration of zirconium is unrelated to the distance from the Piedmont, the equivalent thorium concentration, and the watershed. These findings establish a foundation for more sophisticated analyses using integrated spatial modeling.

Open-File Report↗
USGS2026

Floods of June 20–July 6, 2024, in the Big Sioux River, Rock River, Little Sioux River, Ocheyedan River, and Floyd River Basins, northwestern Iowa

Major flooding occurred on June 20–July 6, 2024, in northwestern Iowa affecting the Big Sioux, Rock, Little Sioux, Ocheyedan, and Floyd River Basins. Heavy rain fell in northwestern Iowa, southwestern Minnesota, and southeastern South Dakota on June 20–22, 2024. Parts of northwestern Iowa recorded 2–6 inches of rainfall and localized amounts exceeding 12 inches. A maximum peak-of-record streamflow of 175,000 cubic feet per second at the U.S. Geological Survey streamgage Big Sioux River at Akron, Iowa (06485500), was recorded on June 22, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at four locations along the Big Sioux River between U.S. Interstate 29 at Sioux City, Iowa, upstream to Iowa Highway 10 north of Hawarden, Iowa, a distance of 75.7 river miles. A maximum peak-of-record streamflow of 157,000 cubic feet per second at the U.S. Geological Survey streamgage Rock River near Rock Valley, Iowa (06483500), was recorded on June 22, 2024, and had an annual exceedance probability of less than 0.2 percent. High-water marks were measured at eight locations along the Rock River between County Road B30 east of Hudson, South Dakota, upstream to Iowa Highway 9 at Rock Rapids, Iowa, a distance of 39.3 river miles. A maximum peak-of-record streamflow of 63,000 cubic feet per second at the U.S. Geological Survey streamgage Little Sioux River at Correctionville, Iowa (06606600), was recorded on June 24, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at 11 locations along the Little Sioux River between Iowa Highway 31 west of Correctionville, Iowa, upstream to U.S. Highway 18 north of Spencer, Iowa, a distance of 134.8 river miles. A maximum streamflow of 24,500 cubic feet per second at the U.S. Geological Survey streamgage Ocheyedan River near Spencer, Iowa (06605000), was recorded on June 22, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at three locations along the Ocheyedan River between County Road M38 west of Spencer, Iowa, upstream to U.S. Highway 18 west of Everly, Iowa, a distance of 12.8 river miles. A maximum streamflow of 41,000 cubic feet per second at the U.S. Geological Survey streamgage Floyd River at Alton, Iowa (06600100), was recorded on June 22, 2024, and had an annual exceedance probability range of 1–1.99 percent. High-water marks were measured at six locations along the Floyd River between Iowa Highway 3 at Le Mars, Iowa, upstream to Iowa Highway 10 at Alton, Iowa, a distance of 27.5 river miles. The high-water marks were used to develop flood profiles for the Big Sioux, Rock, Little Sioux, Ocheyedan, and Floyd Rivers.

Iowa, Minnesota, South Dakota↗
USGS2011

Water-level surface in the Chicot equivalent aquifer system in southeastern Louisiana, 2009

The Chicot equivalent aquifer system is an important source of freshwater in southeastern Louisiana. In 2005, about 47 million gallons per day (Mgal/d) were withdrawn from the Chicot equivalent aquifer system in East Baton Rouge, East Feliciana, Livingston, Tangipahoa, St. Helena, St. Tammany, Washington, and West Feliciana Parishes. Concentrated withdrawals exceeded 5 Mgal/d in Bogalusa, the city of Baton Rouge, and in northwestern East Baton Rouge Parish. In the study area, about 30,000 wells screened in the Chicot equivalent aquifer system were registered with the Louisiana Department of Transportation and Development (LaDOTD). These wells were constructed for public-supply, industry, irrigation, and domestic uses. Most of the wells were registered as domestic-use wells and are small-diameter, low-yielding wells. Total withdrawal from the Chicot equivalent aquifer system for domestic use was estimated to be 12 Mgal/d in 2005. This report documents the 2009 water-level surface of the Chicot equivalent aquifer system in southeastern Louisiana. The report also shows differences in water-level measurements for the years 1991 and 2009 at selected sites. Understanding changes and trends in water levels is important for continued use, planning, and management of groundwater resources. The U.S. Geological Survey, in cooperation with the Louisiana Department of Transportation and Development, conducted this study of the water-level surface of the Chicot equivalent aquifer system as part of an ongoing effort to monitor groundwater levels in aquifers in Louisiana.

Louisiana↗
USGS2020

Methods for estimating selected low-flow frequency statistics and mean annual flow for ungaged locations on streams in Alabama

Streamflow data and statistics are vitally important for proper protection and management of the water quality and water quantity of Alabama streams. Such data and statistics are generally available at U.S. Geological Survey streamflow-gaging stations, also referred to as streamgages or stations, but are often needed at ungaged stream locations. To address this need, the U.S. Geological Survey, in cooperation with numerous Alabama State agencies and organizations, developed regional regression equations for estimating selected low-flow frequency statistics and mean annual flow for ungaged locations on streams in Alabama that are not substantially affected by tides, regulation, diversions, or other anthropogenic influences. A small percentage of the streamgages included in this study experience zero flows during certain periods; thus, the final low-flow frequency regression equations were developed by using weighted left-censored regression analyses to analyze the flow data in an unbiased manner, with weights based on number of years of record. The equations developed include the annual minimum 1- and 7-day average streamflows with a 10-year recurrence interval (referred to as the 1Q10 and 7Q10 flows), the annual minimum 7-day average streamflow with a 2-year recurrence interval (referred to as the 7Q2 flow), and the mean annual flow using data from 174 streamgages from Alabama and surrounding States. For the 1Q10, 7Q2, and 7Q10 low-flow frequency statistics, the regional regression equations are functions of drainage area, streamflow-variability index, mean annual precipitation, and percentage of the drainage basin located in the Piedmont and Southeastern Plains ecoregions. The mean annual flow regression equation is a function of drainage area, mean annual precipitation, and percentage of the drainage basin located in the Southeastern Plains ecoregion. For the mean annual flow regression equation, the average standard error of estimate was 11.2 percent. For the selected low-flow frequency equations, the average standard errors of estimate ranged from 18.1 to 38.8 percent. The regional regression equations developed from this investigation have been incorporated into the U.S. Geological Survey StreamStats application for Alabama. StreamStats ( https://streamstats.usgs.gov/ss/ ) is a web-based geographic information system application that delineates drainage basins at selected stream locations and then generates the needed basin characteristics for available regional regression equations. Along with the low-flow frequency equations developed in this investigation, the StreamStats application also has regional regression equations for estimating flood-frequency statistics at locations on rural and urban streams in Alabama.

Alabama↗
USGS2005

Multi-decadal impacts of grazing on soil physical and biogeochemical properties in southeast Utah

Many soils in southeastern Utah are protected from surface disturbance by biological soil crusts that stabilize soils and reduce erosion by wind and water. When these crusts are disturbed by land use, soils become susceptible to erosion. In this study, we compare a never-grazed grassland in Canyonlands National Park with two historically grazed sites with similar geologic, geomorphic, and geochemical characteristics that were grazed from the late 1800s until 1974. We show that, despite almost 30 years without livestock grazing, surface soils in the historically grazed sites have 38–43% less silt, as well as 14– 51% less total elemental soil Mg, Na, P, and Mn content relative to soils never exposed to livestock disturbances. Using magnetic measurement of soil magnetite content (a proxy for the stabilization of far-traveled eolian dust) we suggest that the differences in Mg, Na, P, and Mn are related to wind erosion of soil fine particles after the historical disturbance by livestock grazing. Historical grazing may also lead to changes in soil organic matter content including declines of 60–70% in surface soil C and N relative to the never-grazed sites. Collectively, the differences in soil C and N content and the evidence for substantial rock-derived nutrient loss to wind erosion implies that livestock grazing could have long-lasting effects on the soil fertility of native grasslands in this part of southeastern Utah. This study suggests that nutrient loss due to wind erosion of soils should be a consideration for management decisions related to the long-term sustainability of grazing operations in arid environments.

Utah↗
USGS2009

Thermal maturity and organic composition of Pennsylvanian coals and carbonaceous shales, north-central Texas: Implications for coalbed gas potential

Thermal maturity was determined for about 120 core, cuttings, and outcrop samples to investigate the potential for coalbed gas resources in Pennsylvanian strata of north-central Texas. Shallow (< 600??m; 2000??ft) coal and carbonaceous shale cuttings samples from the Middle-Upper Pennsylvanian Strawn, Canyon, and Cisco Groups in Archer and Young Counties on the Eastern Shelf of the Midland basin (northwest and downdip from the outcrop) yielded mean random vitrinite reflectance (Ro) values between about 0.4 and 0.8%. This range of Ro values indicates rank from subbituminous C to high volatile A bituminous in the shallow subsurface, which may be sufficient for early thermogenic gas generation. Near-surface (< 100??m; 300??ft) core and outcrop samples of coal from areas of historical underground coal mining in the region yielded similar Ro values of 0.5 to 0.8%. Carbonaceous shale core samples of Lower Pennsylvanian strata (lower Atoka Group) from two deeper wells (samples from ~ 1650??m; 5400??ft) in Jack and western Wise Counties in the western part of the Fort Worth basin yielded higher Ro values of about 1.0%. Pyrolysis and petrographic data for the lower Atoka samples indicate mixed Type II/Type III organic matter, suggesting generated hydrocarbons may be both gas- and oil-prone. In all other samples, organic material is dominated by Type III organic matter (vitrinite), indicating that generated hydrocarbons should be gas-prone. Individual coal beds are thin at outcrop (< 1??m; 3.3??ft), laterally discontinuous, and moderately high in ash yield and sulfur content. A possible analog for coalbed gas potential in the Pennsylvanian section of north-central Texas occurs on the northeast Oklahoma shelf and in the Cherokee basin of southeastern Kansas, where contemporaneous gas-producing coal beds are similar in thickness, quality, and rank.

International Journal of Coal Geology↗