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Scientific Investigations Report

Scientific Investigations Report: explore 90 source-linked works published from 2016 to 2026, with original documents and citations.

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Includes records with this source-supplied label or an explicit phrase match in their metadata. Matches indicate a mention, not proof that a paper uses a method or tests a material. Source versions are consolidated by DOI.

Sources: usgs. Collection updated 2026-09-15. Counts describe this index, not the complete source archives.

USGS2026

Flood-inundation maps of the Blue River and major tributaries in and near Kansas City, Missouri, 2023–25

Digital flood-inundation maps for 35.5 miles of the Blue River, in and near Kansas City, Missouri, were created by the U.S. Geological Survey (USGS) in cooperation with the City of Kansas City. Maps were also developed for a combined 7.3 miles of Brush Creek (4.4 miles) and Indian Creek (2.9 miles), two primary tributaries to the Blue River in the study reach. The flood-inundation maps, available through the USGS Flood Inundation Mapping Program website at https://water.usgs.gov/osw/flood_inundation/ , depict estimates of the areal extent and depth of flooding, depth of water above first-floor elevations in selected buildings, water velocity, water-surface elevations, and time of travel corresponding to selected water levels or gage heights (hereafter referred to as “stages”) at nine reference USGS streamgages—five on the Blue River (USGS station numbers 06893590, 06893578, 06893500, 06893150, and 06893100), two on Brush Creek (USGS station numbers 06893562 and 06893557), one on Indian Creek (USGS station number 06893390), and one on the Missouri River (USGS station number 06893000). Near-real-time stages at these streamgages may be obtained from USGS Water Data for the Nation at https://doi.org/10.5066/F7P55KJN or the National Weather Service National Water Prediction Service at http://water.noaa.gov/ , which also forecasts flood hydrographs at seven of these sites (USGS station numbers 06893000, 06893590, 06893578, 06893500, 06893150, 06893557, and 06893390). Flood profiles were computed for eight map reaches by means of two-dimensional hydraulic models. The models were calibrated using the USGS-developed stage–streamflow relations at each reference streamgage. Two map reaches on the lower Blue River also include the effects of backwater from the Missouri River on flood inundation extent and hydraulic characteristics. The hydraulic models were used to compute water-surface profiles for flood stages at 1-foot intervals referenced to the streamgage datums. The profile stages ranged from the National Weather Service “Action Stage” or near bankfull to a stage exceeding the highest recorded water level at each streamgage. The simulated water-surface profiles were then combined with a digital elevation model (derived from light detection and ranging data having a nonvegetated vertical accuracy of a maximum 10-centimeter root-mean-square error) to delineate the area flooded at each water level and the associated hydraulic characteristics. The availability of these maps, along with information regarding current stage from the USGS streamgage and forecasted high-flow stages from the National Weather Service, will provide emergency management personnel, resource managers, and residents with information that could be critical for flood-response activities such as evacuations and road closures, as well as for postflood recovery efforts.

Kansas, Missouri↗
USGS2026

Assessing the state of hydrologic science in the Upper Klamath Basin—A comprehensive review of data, tools, and models

Water demand in the Upper Klamath Basin (UKB) from various stakeholders and ecological needs often outstrips available supply, leading to persistent management challenges. This study reviews the state of hydrologic science within the UKB as of 2025—specifically, the tools, data, and models available for assessing five key components of the water system: (1) surface water; (2) precipitation; (3) evapotranspiration; (4) groundwater; and (5) water use. The UKB water supply is critical for Native American communities, regional agriculture, and federally listed fishes and faces challenges from competing needs, climate variability, and operational/regulatory requirements. We assess existing datasets, regional and national models, and historical studies to understand the available resources and identify gaps that may hinder integrated water assessments and management. Our findings indicate areas where improvements in data collection and model precision could improve the accuracy of water-availability forecasts and support water-management practices. This review can inform near-term forecasting, assist in optimizing water-resource data collection and management strategies, and support regional water-availability assessments of the basin.

Oregon↗
USGS2026

Evaluation of nutrient, alkalinity, and acid-neutralizing capacity stabilities in water samples analyzed by the U.S. Geological Survey National Water Quality Laboratory, 2023–24

The U.S. Geological Survey evaluated the stability of water-sample chemical analysis of nutrient, alkalinity, and acid-neutralizing capacity constituents with respect to the duration between sample collection and laboratory analysis, also known as the sample holding time. A study began in the spring of 2023 to evaluate the sample stability, between 2 and 180 days after sample collection, of the chemical properties and chemical constituents of alkalinity as calcium carbonate, filtered; acid-neutralizing capacity as calcium carbonate, unfiltered; total ammonia as nitrogen, filtered; total ammonia plus organic nitrogen as nitrogen, filtered and unfiltered; nitrite as nitrogen, filtered; nitrate plus nitrite as nitrogen, filtered; total nitrogen, filtered and unfiltered; orthophosphate as phosphorous, filtered; and total phosphorus as phosphorus (filtered and unfiltered) in water. Both surface water and groundwater matrices were represented. Sample instability varied by observed property and matrix; therefore, providing general guidance for sample holding time is not possible based on matrices alone. No correlations between field measurements of sample characteristics and sample instability were observed. Although observations for some properties indicate sample stability that exceeds the recognized U.S. Geological Survey National Water Quality Laboratory method holding times, this is not necessarily the case for matrices and seasonal characteristics that were not investigated. Based on the limited number of six sample sources used in this study, some patterns emerge for the 12 observed properties studied. Five observed properties generally indicate stability for as many as 180 days after sampling (total nitrogen as nitrogen, both filtered and unfiltered; orthophosphate as phosphorus, filtered; and phosphorus as phosphorus, both filtered and unfiltered). Other observed properties indicate stability for as many as 180 days for some matrices, but not for others. Finally, some observed properties indicate instability well before 180 days.

Scientific Investigations Report↗
USGS2026

Status and understanding of groundwater quality in the San Joaquin Valley Kern County subbasin domestic-supply aquifer study unit, 2022—California GAMA Priority Basin Project

The quality of water accessed by domestic wells (here referred to as domestic groundwater resources) in the San Joaquin Valley Kern County subbasin (basin number 5-022.14) was assessed as part of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project (GAMA-PBP), in cooperation with the California State Water Resources Control Board. Kern County is at the southern end of the San Joaquin Valley in California, and about 30,000 residents are estimated to use privately owned domestic wells for drinking water. Domestic wells typically draw from shallower parts of the aquifer system than public-supply wells and can be more vulnerable to effects from surface activities. Kern County is host to a highly productive agricultural industry, with Bakersfield as the main urban center. The Kern River runs through Bakersfield from the southern Sierra Nevada and intersects the Kern Water Bank, one of the largest groundwater banking operations in California, at the Kern River Intertie. The section of the Kern River running through the Kern Water Bank is dry most years. Kern County also encompasses some of the most productive oil and gas basins in California, with extensive underground and surface disposal of oil-field wastewater. This study was based on data collected from 33 sites sampled by the U.S. Geological Survey for the GAMA-PBP in 2022. To provide context for the water quality assessment, measured concentrations were compared to regulatory and non-regulatory health-based and aesthetic benchmarks. A grid-based method was used to estimate the proportions of the groundwater resources used for domestic-supply wells that have water-quality constituents below (low relative concentration), approaching (moderate relative concentration), or above (high relative concentration) benchmark concentrations. At least one measured constituent with a regulatory benchmark was categorized as having a high relative concentration in 72 percent of the aquifer area used for domestic groundwater resources. Inorganic constituents were detected at high concentrations in 45 percent of the domestic groundwater resources, and the constituents detected above regulatory benchmarks were arsenic, nitrate, and uranium. At least one organic constituent was detected at high concentrations in 41 percent of the domestic groundwater resources, and the constituents exceeding regulatory benchmarks were the fumigants 1,2,3-trichloropropane (1,2,3-TCP), 1,2-dibromo-3-chloropropane (dibromochloropropane [DBCP]), 1,2-dibromoethane (EDB), and the per-and polyfluoroalkyl substance (PFAS) perfluorooctanesulfonate. The disinfection by-product chloroform, the fumigant 1,2-dichloropropane, the herbicides atrazine and hexazinone, and the herbicide degradates 2-chloro-6-ethylamino-4-amino-s-triazine, 2-chloro-4,6-diamino-s-triazine, 4-hydroxychlorothalonil, and metolachlor sulfonic acid were detected in more than 10 percent of domestic groundwater resources, but concentrations did not exceed regulatory benchmarks. Land use, groundwater age (fraction of modern water and mean age), and geochemical environment (oxic or anoxic conditions, pH, alkalinity) were associated with the distribution of high relative concentrations of inorganic and organic constituents. Young, oxygenated water is recharged along the Kern River and adjacent recharge ponds, or as irrigation water in the agricultural areas. High concentrations of nitrate and volatile organic compounds occurred in the oxic water in urban and agricultural areas. The fumigants 1,2,3-TCP, DBCP, and EDB were reported throughout the agricultural areas, whereas chloroform, tetrachloroethene, and PFAS were associated with urban land use. High uranium concentrations were associated with young, modern groundwater in agricultural areas with low pH and high bicarbonate. Total dissolved solids increased with distance from the Kern River, as the contributions of fresh, oxic water decreased. High concentrations of arsenic were present in older anoxic or alkaline groundwater away from areas of recharge. Overall, groundwater age, redox conditions, and the source of recharge as a result of different land uses contribute to large aquifer-scale portions of domestic groundwater resources that exceed health-based benchmarks for nitrate, uranium, and fumigant concentrations.

California↗
USGS2026

Precipitation-based flood-inundation maps for the East Fork Little Blue River and tributaries at Lee’s Summit, Missouri, 2024

The U.S. Geological Survey, in cooperation with the City of Lee’s Summit, Missouri, assessed flooding of the East Fork Little Blue River and tributaries for varying precipitation magnitudes and durations, varying antecedent runoff conditions, and projected climate-change conditions. The precipitation scenarios were used to develop a library of flood-inundation maps for a 2.95-mile reach of the East Fork Little Blue River and tributaries within the city. A two-dimensional U.S. Army Corps of Engineers Hydrologic Engineering Center–River Analysis System (HEC–RAS; ver. 6.5) rain-on-grid model was calibrated to selected runoff events representing a range of antecedent runoff conditions and hydrologic responses. Lowest adjacent grades for structures within the nearby study area were incorporated into the terrain, and depth grids and water-surface elevation grids were developed for the study area. Simulated velocities at selected bridge locations were also developed from the model. The model was calibrated using water-surface elevation data collected from water-level loggers (pressure transducers) and streamflow measurements and water-surface elevation measurements made at a reference point during runoff events. The calibrated HEC–RAS model was used to simulate streamflows from design rainfall events of 15-minute to 24-hour durations and ranging from a 100- to 0.1-percent annual exceedance probability (1-year to 1,000-year recurrence intervals). Flood-inundation maps were produced for depths at a reference location of 3 to 16 feet, or a depth exceeding the 0.1-percent annual exceedance probability interval precipitation. The results of each precipitation duration-frequency value were represented by a 1-foot-increment inundation map based on the generated peak streamflow from that rainfall event and the corresponding water-surface elevation at the East Fork Little Blue River reference location. Within the HEC–RAS model, 240 scenarios were developed from the design rainfall events with each of 3 antecedent conditions. Additional scenarios were created to simulate the effects of projected precipitation scenarios on the 100-year recurrence interval, 24-hour storm and the 100-year recurrence interval, 6-hour storm. All simulation results were assigned to a flood-inundation map condition based on the generated peak flow and corresponding water-surface elevation at the East Fork Little Blue River reference location. The flood-inundation maps are shown on a web mapping application made available to the public through the City of Lee’s Summit (hyperlink will be added when available). The flood-inundation maps are tied to real-time precipitation data obtained from the Automated Surface Observing System weather station at the Lee’s Summit Municipal Airport, accessible at https://mesonet.agron.iastate.edu/request/download.phtml?network=MO_ASOS . The availability of these maps, along with information regarding observed rainfall, could help 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↗
USGS2026

Salinas Valley integrated hydrologic and reservoir operations models, Monterey and San Luis Obispo Counties, California

The area surrounding the Salinas Valley groundwater basin in Monterey and San Luis Obispo Counties of California is a highly productive agricultural area, contributes substantially to the local economy, and provides a substantial portion of vegetables and other agricultural commodities to the Nation. This region of California provides about half of the Nation’s lettuce, celery, broccoli, and spinach each year. Thus, this agricultural area provides substantial volumes of agricultural products not just for California but for the United States. Changes in population and increased agricultural development, which includes a shift toward more water-intensive crops, and climate variability, have put increasing demand on both surface-water and groundwater resources in the valley. This situation has resulted in water management challenges in the Salinas Valley that generally relate to the distribution of the water supply throughout the basin. Where and when the water is present in the surface and subsurface does not coincide with where and when the water is needed. Historically, to deal with the distribution issue, water has been used conjunctively in the valley. Conjunctive use is a water management strategy that coordinates surface-water and groundwater use to maximize water availability. Groundwater is used throughout the Salinas Valley to meet water demands when surface-water supplies are insufficient. The availability of surface water is constrained by climate. Precipitation and streamflow vary seasonally and year to year. Although there are two reservoirs in the Salinas Valley to capture and store water during wet periods, the only conveyance of reservoir water to coastal agricultural areas is the Salinas River. Increasing demand for groundwater and surface-water resources throughout the Salinas Valley has resulted in undesirable effects from unsustainable water use, such as surface-water depletion, groundwater-level declines, storage depletion in the principal aquifers, and seawater intrusion. To address these escalating issues, local communities, water management agencies, and groundwater sustainability agencies are evaluating how to sustainably manage both their surface-water and groundwater resources. To meet water demands and reduce the undesirable effects of unsustainable water use, continued conjunctive management of surface water and groundwater would ideally incorporate strategies to deal with increases in demand and climate variability. To evaluate the challenging water management issues in the Salinas Valley, the U.S. Geological Survey, Monterey County Water Resources Agency, and the Salinas Valley Basin Groundwater Sustainability Agency developed a comprehensive suite of models that represent the Salinas Valley hydrogeologic system called the Salinas Valley System Model. The geologic framework is known as the Salinas Valley Geologic Framework and was developed to characterize the subsurface using various topographic and geologic data sources, including information on hydrogeologic units, their surfaces and extents, geologic structures, lithology, and elevations from borehole data and cross sections, as well as details on faults and existing models. The surface-water model is called the Salinas Valley Watershed Model and simulates the Salinas River watershed. Monthly surface-water inflows into the integrated hydrologic model domain were simulated using the Salinas Valley Watershed Model. The historical model uses historical climate data, water and land use data, and reservoir releases to simulate agricultural operations, including landscape water demands, diversions, and reclaimed wastewater. The operational model adds an embedded reservoir operations framework to the simulation of the historical model that allows specified operational rules to simulate reservoir releases and changes in reservoir storage. The operational model assumes current reservoir operations and constant land use, which differs from historical conditions. Thus, the operational model is a hypothetical baseline model that can be used by local water managers to evaluate and quantify potential benefits of water supply projects. Together, the geologic framework, watershed, historical, and operational models form a tool that can be used to simulate irrigated agriculture and associated reservoir operations of the integrated hydrologic system of the Salinas Valley.

California↗
USGS2026

Top Elevation of Glacial Till and Thickness of the Big Sioux Aquifer Delineated From Electrical Resistivity Tomography Surveys Near Sioux Falls, South Dakota, 2022 and 2025

The City of Sioux Falls, South Dakota, requested the U.S. Geological Survey perform electrical resistivity surveys on three parcels of land north of the city. Electrical resistivity data were collected along a total of 22 transects during March 14–18, 2022, and November 17–21, 2025. Results from electrical resistivity surveys were used to delineate the top of glacial till deposits for the purpose of characterizing the Big Sioux aquifer near the city. Delineating geologic contacts provides important information on groundwater storage, flow dynamics, well design and placement, contaminant transport, groundwater–surface-water interactions, and regional water modeling. The top elevation of glacial till and the thickness of the Big Sioux aquifer varied among the three survey areas. The interpreted top elevation of glacial till in the North survey area decreases from east to west toward a slough, with elevations ranging from 1,403 to 1,418 feet (ft). The estimated thickness of the Big Sioux aquifer in the North survey area increased from east to west, with thicknesses ranging from 23 to 38 ft. The top elevation of glacial till in the Well 72 survey area generally decreases from northwest to southeast. Top elevations of the glacial till in the Well 72 survey area ranged from 1,400 to 1,409 ft along the southern end of transect W72_2. The estimated thickness of the Big Sioux aquifer in the Well 72 survey area was greatest along a southeast to northwest trending channel, with thicknesses ranging from 28 to 40 ft. The top elevation of glacial till in the Nose survey area generally decreases west toward the Big Sioux River. Top elevations of the glacial till in the Nose survey area ranged from 1,362 to 1,395 ft. The estimated thickness of the Big Sioux aquifer in the Nose survey area ranged from 33 to 70 ft.

South Dakota↗
USGS2026

Simulation of groundwater flow to evaluate hydrogeologic controls on a PFAS plume, Coakley Landfill Superfund site, Rockingham County, New Hampshire

Per- and polyfluoroalkyl substances (PFAS), including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), have been detected at combined concentrations above 2,000 nanograms per liter (ng/L) at groundwater seep locations near the Coakley Landfill Superfund site, in North Hampton, New Hampshire. The landfill was active from 1972 to 1985. An impermeable cap was placed on the landfill in 1998. The adjacent area to the Coakley Landfill has many water supply wells, and transport of PFAS compounds to the wells is a concern. Fracture anisotropy in the underlying bedrock aquifer complicates the understanding of PFAS transport because groundwater preferentially travels along fractures that may not align with the prevailing groundwater flow direction. In 2018, the U.S. Environmental Protection Agency and the U.S. Geological Survey began an investigation of the groundwater flow from the Coakley Landfill site. This report describes the modification of a numerical groundwater-flow model for the local area around the Coakley Landfill and summarizes findings of the investigation. In addition, this report includes a brief description of PFOA and PFOS occurrence, a discussion of model construction, evaluation of model performance through calibration, and discussion of simulation results for two periods (before and after capping). Limitations are also discussed. Results show that simulated groundwater flow moves from the Coakley Landfill to the west and north. Advective transport modeling using particle tracking shows that groundwater from the landfill discharges primarily to streams to the west and north, and a small amount is transported to distal wells. Dilution of contaminants through advection and dispersion likely plays a role in whether PFAS compounds from the landfill will be detected above laboratory reporting levels at distal wells.

New Hampshire↗
USGS2026

Hydrogeologic framework and conceptual groundwater-flow model of the panhandle and northwest parts of the High Plains (Ogallala) aquifer in Oklahoma, 1998–2022

This study was conducted by the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, to update the hydrogeologic framework and conceptual flow model for the panhandle and northwest parts of the High Plains (Ogallala) aquifer in Oklahoma, which together compose the Ogallala aquifer focus area. The study included the construction of a potentiometric surface, and available geologic and hydrologic data were used to evaluate saturated thickness of the aquifer. The water budget for the updated conceptual groundwater-​flow model was based on estimated inflows and outflows for the 1998–2022 study period. Saturated thickness of the Ogallala aquifer averaged 127 and 116 feet for the panhandle and northwest parts, respectively. Groundwater withdrawals from the Ogallala aquifer for 1998–2022 averaged 422,054 and 39,645 acre-feet per year (acre-ft/yr) for the panhandle and northwest parts, respectively. Recharge, the primary inflow, was estimated at 0.63 inch per year for the 1998–2022 study period, with the panhandle part of the Ogallala aquifer receiving 175,068 acre-ft/yr and the northwest part of the Ogallala aquifer receiving 49,376 acre-ft/yr. Additional inflows included irrigation return flows, estimated at 8,111 and 642 acre-ft/yr for the panhandle and northwest parts, respectively, of the Ogallala aquifer. Net lateral groundwater flows, considered to be aquifer outflows, were estimated to account for 31,908 acre-ft/yr for the Ogallala aquifer focus area. Streambed seepage, which was an outflow of 5,535 acre-ft/yr, was only present in the northwest part of the Ogallala aquifer. Vertical leakage and saturated-zone evapotranspiration were considered negligible outflows. These findings provide a revised conceptual groundwater-flow model water budget for the Ogallala aquifer focus area in Oklahoma.

Colorado, Kansas, Oklahoma, Texas↗
USGS2026

Water use in Louisiana, 2020

The U.S. Geological Survey (USGS), in cooperation with the Louisiana Department of Transportation and Development, collected water-withdrawal and water-use data from a 2020 inventory of water withdrawals in Louisiana. In 2020, approximately 8,700 million gallons per day (Mgal/d) of water was withdrawn from groundwater and surface-water sources in Louisiana, which represented a 0.22-percent decrease from 2015. Total groundwater withdrawals were about 1,900 Mgal/d, an increase of 7.1 percent from 2015, and total surface-water withdrawals were about 6,800 Mgal/d, a decrease of 2.1 percent from 2015 to 2020. Total water withdrawals, in million gallons per day, in 2020 for the various categories of use were as follows: public supply, 720; industry, 2,100; power generation, 4,100; rural domestic, 39; livestock, 7.0; rice irrigation, 930; general irrigation, 250; and aquaculture, 590. From 2015 to 2020, Louisiana’s total withdrawals for public supply increased by 1.4 percent, industry decreased by 2.3 percent, power generation decreased by 4.9 percent, rural domestic decreased by 1.2 percent, livestock increased by 11 percent, rice irrigation increased by 13 percent, general irrigation increased by 12 percent, and aquaculture increased by 20 percent. About 51 percent (approximately 960 Mgal/d) of all groundwater withdrawn was from the Chicot aquifer system and 24 percent (approximately 450 Mgal/d) was withdrawn from the Mississippi River alluvial aquifer. Since 2015, withdrawals from the Chicot aquifer system increased by 13 percent, and withdrawals from the Mississippi River alluvial aquifer increased by 18 percent. About 72 percent (4,900 Mgal/d) of all surface water withdrawn was from the Mississippi River main stem. This value represents a 1.1-percent decrease in withdrawals from 2015 to 2020. All water-withdrawal and water-use data presented in this report should be considered estimates. Because of rounding, totals and percentages presented in the tables, figures, and text in the report may differ slightly from totals or percentages calculated individually.

Louisiana↗
USGS2026

Shallow hydrogeologic framework of the Tully Valley mudboil area, Onondaga County, New York

Mudboils have been documented in the Tully Valley in southern Onondaga County, New York, since the late 1890s. Sediment-laden water from the mudboils flows into Onondaga Creek, which empties into Onondaga Lake at Syracuse 15 miles to the north. Turbidity from the mudboils has degraded the water quality of Onondaga Creek despite a series of mitigation efforts that began in the early 1990s. Turbidity mitigation actions presently (2025) being considered include creek relocation and offline sediment settling. In support of these proposed actions during 2021–23, the U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, U.S. Environmental Protection Agency, Onondaga Nation, Onondaga Environmental Institute, and Central New York Regional Planning and Development Board, collected and analyzed geologic, hydrologic, geophysical, and geotechnical data to characterize the shallow hydrogeology along four proposed creek-relocation paths and in the proposed offline settling basin area. The investigation indicated that the four proposed creek-relocation paths, two east of Onondaga Creek and two west of Onondaga Creek, are underlain by sediments including muck, alluvium, mudboil deposits, alluvial-fan sand and gravel, and lacustrine fines. The proposed excavations would penetrate partially to fully saturated conditions: generally, the water table is shallow near the creek and deep on the alluvial fans. The shallowest excavation, about 5 feet below land surface, would be near the creek and primarily in alluvium, and the deepest excavation, as much as 30 feet below land surface, would be in the alluvial-fan deposits. Brackish waters would be penetrated by proposed channel excavations on the eastern side of Onondaga Creek in an area downgradient from a potentially leaking historical salt-exploration borehole and near the main mudboil area. Excavation in these areas likely would provide a continuous source of brackish groundwater to the relocated creek. Proposed channel excavations of muck, soft to very soft lacustrine fines, and mudboil-type sediments in mudboil and suspected mudboil areas would pose an excavation and slope stability challenge and would have the greatest potential to create new mudboils. Proposed channel excavations below the water table on the Rattlesnake Gulf and Rainbow Creek alluvial fans would intercept groundwater and make the constructed streambank susceptible to seepage-induced slope instability. The substantial water-level fluctuation in the sediments of both alluvial fans would aggravate the stability condition. In addition, excavation on the Rattlesnake Gulf alluvial fan would have the potential to affect water-supply springs at the toe of the fan. The proposed offline settling basin area is in the northern part of the Rattlesnake Gulf alluvial fan. Natural and man-made diversions of Rattlesnake Gulf have resulted in saturated conditions in the general area of the proposed basin. The proposed offline settling basin would be excavated in, and berms would be constructed on, alluvial-fan deposits and lacustrine fines. In the proposed basin area, the alluvial deposits overlying the lacustrine fines are less than 10 feet thick. Excavation, berm construction, and loading of the saturated, soft to very soft lacustrine fines may be problematic and require soil strengthening.

New York↗
USGS2026

Hydrologic investigation of water level fluctuations at Moreau Lake, Moreau Lake State Park, town of Moreau, New York

The causes of water level fluctuations at Moreau Lake, within Moreau Lake State Park in the town of Moreau, New York, were investigated from 2016 to 2021 after lake water levels dropped between 2015 and 2016, raising concerns about the loss of a shallow swimming area at the park beach. Annual variation in precipitation records from the area did not account for the lake water level decline. Two possible causes for the low lake water levels were investigated: the increase in groundwater withdrawals from new residential development since about 2000 and seasonal changes (nongrowing and growing seasons) in precipitation. Investigation of the potential effects of nearby groundwater withdrawals required the compilation and collection of well-log data, seismic surveys, and measurements of lake and groundwater levels, field chemical parameters, and water isotopes to define the hydrogeologic system and to estimate water use. The net result of this work was the determination that Moreau Lake is a “flow though” lake with no surface water outlet; groundwater enters the lake on the upgradient side and exits through the downgradient side, however, groundwater does not flow southward from the lake toward nearby groundwater withdrawals from the semiconfined aquifer, and thus groundwater withdrawals were unlikely to have an effect on lake water levels. Investigation of the historic precipitation records during nongrowing (November through April) and growing (May through October) indicated that (1) nongrowing season precipitation from 2011–12 to 2015–16 was more deficient than any similar period during the past 78 years and (2) since about 2000, nongrowing seasons have been drier overall and growing seasons have been considerably wetter. Initiation of lake water level monitoring in 2016 provided an opportunity to compare seasonal precipitation with seasonal lake water level changes. Nongrowing season lake water levels are very sensitive to precipitation, such that high precipitation (40 percent above the seasonal median) resulted in a 5-foot rise in lake water level. In contrast, the growing season lake water levels are sensitive to dry conditions; for example, deficient rainfall (about 6 percent below the seasonal median) resulted in a decline of lake water levels of about 3.5 feet. However, lake water levels are insensitive to high growing season rainfall inputs (about 10 to 47 percent above the seasonal median); lake water levels consistently declined about by 0.8 feet above this range of seasonal excessive precipitation.

New York↗
USGS2026

Assessment of groundwater quantity and quality contributions to Lake Huron

Lake Huron, one of the five Great Lakes, borders the United States and Canada, with Michigan as the only U.S. State on its shoreline. Like other freshwater lakes, it faces water-quality challenges from nutrients and chemicals applied across its drainage basin. Although past studies focused on surface-water sources, groundwater contributions remain less understood. To address this gap, the U.S. Geological Survey, as part of the Cooperative Science and Monitoring Initiative, classified drainage basins to Lake Huron into eight hydrogeologic zones based on bedrock rock type and glacial sediment transmissivity. Utilizing existing data and empirical field data, we quantified groundwater discharge and identified areas of concern for loading of chloride and nitrate to Lake Huron. Groundwater contributions, including indirect and shoreline discharge, ranged from 5.8 to 11.5 inches annually, totaling 1.9 cubic miles and 0.09 cubic mile, respectively. Hydrogeologic zones with higher glacial sediment transmissivity yielded greater indirect groundwater discharge. Chloride levels above the U.S. Environmental Protection Agency’s 250-mg/L recommendation were mainly in the Saginaw lowlands, whereas nitrate above the 10-mg/L standard was rare—found in only 11 wells. Together, the analysis of where groundwater discharge is occurring in the Lake Huron Basin and the identification of areas with potential groundwater-quality concerns can help prioritize areas that are critical to protecting the long-term health of Lake Huron.

Michigan↗
USGS2026

Escherichia coli monitoring and assessment in 2022 and 2023 after beach restoration at Lake St. Clair Metropark Beach, Macomb County, Michigan

Lake St. Clair Metropark Beach in Michigan has a history of closures because of elevated Escherichia coli ( E. coli ) concentrations in its recreational waters. To reduce closures, restoration projects were implemented in 2021 to deter waterfowl from congregating on the beach. In this study, the U.S. Geological Survey, in cooperation with the Michigan Department of the Environment, Great Lakes, and Energy and in collaboration with Huron-Clinton Metroparks and the Macomb County Health Department, monitored E. coli from 2022–23 in surface water, shallow groundwater, and sediment at Lake St. Clair Metropark Beach. Results were compared to data from a prerestoration (2018–19) study. A significant decrease in daily geometric mean E. coli concentrations in surface water was observed postrestoration, but the number of high concentration events increased. This resulted in more frequent beach closures postrestoration. Surface-sediment E. coli concentrations significantly decreased after restoration, and waterfowl populations generally decreased from 2021 to 2023, suggesting that the deterrence measures could be influencing E. coli concentrations in surface sediments and surface water. Groundwater E. coli concentrations were orders of magnitude higher than those in surface water and revealed no change correlated with restoration. Seepage measurements indicated that groundwater occasionally discharges into surface water, potentially providing a transport mechanism for E. coli to reach the lake. Continued monitoring and consideration of environmental factors could help to better understand the beach system.

Michigan↗
USGS2026

Arsenic and isotope concentrations in the lower Platte River valley of eastern Nebraska, early 1970s to 2023

The City of Lincoln, Nebraska, has been monitoring concentrations of arsenic in their source water and evaluating their options for treatment and removal since at least 2002. In 2022, the City of Lincoln, Nebr., with funding assistance from the Nebraska Water Sustainability Fund, began cooperating with the U.S. Geological Survey to examine arsenic concentrations in surface water and groundwater in the lower Platte River valley and the area around City of Lincoln Water System (LWS) well field. Arsenic data collected from the Platte River since 1974 were examined using the “weighted regression on time, discharge, and season” model, which compared the streamflow (also referred to as “discharge”), time of year, and season to estimate concentrations of arsenic. Annual mean arsenic concentrations modeled for more than 49 years at the Platte River at Louisville, Nebr., U.S. Geological Survey streamgage (station 06805500), indicated a significant increasing trend. Arsenic concentrations in the Platte River were seasonal, with the highest concentrations being observed during mid- to late summer. When seasonal patterns and streamflow were combined with arsenic concentrations in the Platte River during low streamflow conditions, groundwater contributions, which can have higher arsenic concentrations, make up a larger portion of the streamflow. Arsenic samples were collected from upstream rivers in 2022 and 2023 and were paired to analyze the arsenic contributions at the U.S. Geological Survey streamgage on the Platte River near Ashland, Nebr. (station 06801000), near the City of Lincoln well field. The arsenic concentrations from the streamgage on the Platte River near Ashland, Nebr., location, were higher than the U.S. Geological Survey streamgage on the Elkhorn River at Waterloo, Nebr. (station 06800500), and significantly lower than at the U.S. Geological Survey streamgage on the Platte River near Leshara, Nebr.(station 06796500), indicating that the Platte River usually contributes a higher concentration of arsenic than does the Elkhorn River as they join near Ashland, Nebr. During 1991–2023, six groundwater monitoring wells were analyzed to identify trends in arsenic concentrations. Two of the six wells had a positive trend during the 33-year period. One monitoring well did not reveal a long-term trend during this period but showed a trend during 2019–23, correlating to a period when the island in the middle of the Platte River was connected to the east bank of the river when manganese reducing conditions were present and groundwater levels were declining in the well. Across all wells the oxidation and reduction (redox) condition during the time of sampling was assessed. Mixed anoxic and (or) oxic redox condition was the most common redox process and the highest sampled arsenic concentrations in monitoring wells were observed in anoxic conditions driven by manganese reduction. Groundwater arsenic concentrations had seasonal variation around the City of Lincoln well field, with higher arsenic concentrations tending to be further south in comparison to samples collected further north. Isotope samples were collected and analyzed in surface water and groundwater around the LWS well field. The samples indicate that the proportion of surface water present in the LWS production wells can be higher in the spring and lower in the summer. With higher arsenic concentrations observed in the stream water during the summer period, the LWS source water can be affected by these elevated arsenic concentrations even though the proportion of surface water is lower.

Nebraska↗
USGS2026

Ungulate migrations of the Western United States, volume 6

This report, volume 6 in the “Ungulate Migrations of the Western United States” report series, showcases the migrations of 23 ungulate herds in the Western United States. The report series is produced by the Corridor Mapping Team (CMT). Led by the U.S. Geological Survey, the CMT is a collaboration among 11 State agencies, as well as regional and Federal partners, and an expanding number of Tribal wildlife agencies. The CMT was initiated in response to the U.S. Department of the Interior Secretarial Order 3362, which was signed in 2018 and provided Federal support to expand existing research efforts to study ungulate populations and conserve their migrations throughout the Western United States. Including this volume, the report series has detailed the migrations of 237 unique ungulate herds throughout the Western United States and continues to serve as a valuable resource to guide local and regional management, policy, and on-the-ground work necessary to maintain intact and functional ungulate migrations. This report highlights several guiding principles of the CMT that facilitate collaboration among the diverse set of partners and contribute to the program’s continued successes. Notably, raw global positioning system data are not shared among participating agencies and the U.S. Geological Survey, delineating migration corridors and seasonal ranges relies on empirical data, the CMT provides flexible approaches to participating State and Tribal partners, and regular CMT meetings create a framework for open communication among agency partners that supports transboundary mapping of migrations. The 237 ungulate migrations that have been included in the report series are an expanding inventory, which can help maintain ungulate migrations in perpetuity.

Arizona, California, Colorado, Idaho, Montana, Nev↗
USGS2026

A three-dimensional geologic framework model of the northern Great Plains region of Montana, North Dakota, South Dakota, and Wyoming, USA

This report presents a new three-dimensional geologic framework model (GFM) of the northern Great Plains region, encompassing parts of Montana, North Dakota, South Dakota, and Wyoming. The model provides a regionally consistent, geographic information system (GIS)-ready representation of Phanerozoic sedimentary strata, major fault systems, and Precambrian basement geometry across two sedimentary basins and adjacent uplifts. More than 300,000 geologic and geophysical data inputs were synthesized to model 41 stratigraphic horizons and 47 faults, yielding an internally coherent, sealed-volume interpretation of the subsurface. The modeling workflow developed for this study demonstrates an efficient and scalable approach for constructing basin-to regional-scale GFMs in geologically complex and data-variable settings. Although model fidelity varies with data density and quality, the resulting geometry is broadly consistent with 1:500,000-scale geologic mapping and highlights areas where additional geologic study is most needed. The three-dimensional GFM provides a foundational framework to support groundwater, energy, and mineral resource assessments, and offers a transferable methodology for potential future U.S. Geological Survey efforts to build large-area subsurface models in underexplored regions of the United States.

Montana, North Dakota, South Dakota, Wyoming↗
USGS2026

Stream sediment sources in Medicine Creek, northern Missouri and southern Iowa

This report presents the results of a cooperative study by the U.S. Geological Survey and Missouri Department of Natural Resources to quantify sediment transport source contributions in the Medicine Creek drainage basin. Understanding relative source contributions provides valuable information for selecting the conservation practices that may be most effective in reducing sediment and sediment-associated nutrient transport in the Medicine Creek drainage basin and similar areas of the Lower Grand River drainage basin. Sediment samples were collected from potential contributing areas (source samples) and from fluvial-transported samples (target samples). Source sample types included streambanks, row crop fields, and a combined pastures and forests category. Samples were analyzed for particle size and quantity of carbon, nitrogen, stable isotopes of carbon and nitrogen, and 49 mineral elements as potential tracers. Results for the carbon stable isotope ratio of carbon-13/carbon-12 (δ 13 C) and concentrations of total carbon, total nitrogen, calcium, potassium, and copper were selected by discriminant function analysis as the best combination of multiple tracers to differentiate each source type. The discriminant function analysis poorly differentiated pastures and forests, so these source types were combined. The sources defined by the discriminant function analysis were then used in an unmixing model to apportion sources for each target sample. In the study area, transported sediment was predominantly bank sediment, with an overall average of 86.9 percent of suspended-sediment samples and depositional streambed samples attributed to bank material. Suspended-sediment samples from the mainstem of Medicine Creek were dominated by bank sediments (average of 95.8 percent), and depositional streambed samples from throughout the drainage basin had more variable source contributions with an average of 71.1 percent attributed to bank material. The relative importance of upland sources (row crop fields and the combined pastures and forests category) varied seasonally and with streamflow but was not related to land use or drainage basin size. Relative contributions from upland sources were greater in the summer through winter rather than spring and during lower streamflow, though this may be driven by the seasonality of streamflow. These results indicate management practices that reduce bank erosion could be effective strategies for managing the dominant source of sediment and sediment-associated phosphorus.

Iowa, Missouri↗
Compare source metadata on this page
WorkPublishedSource identifierSource
Flood-inundation maps of the Blue River and major tributaries in and near Kansas City, Missouri, 2023–252026-06-23sir20265033usgs
Assessing the state of hydrologic science in the Upper Klamath Basin—A comprehensive review of data, tools, and models2026-06-16sir20265139usgs
Evaluation of nutrient, alkalinity, and acid-neutralizing capacity stabilities in water samples analyzed by the U.S. Geological Survey National Water Quality Laboratory, 2023–242026-06-08sir20265014usgs
Status and understanding of groundwater quality in the San Joaquin Valley Kern County subbasin domestic-supply aquifer study unit, 2022—California GAMA Priority Basin Project2026-05-19sir20265012usgs
Precipitation-based flood-inundation maps for the East Fork Little Blue River and tributaries at Lee’s Summit, Missouri, 20242026-05-19sir20265017usgs
Salinas Valley integrated hydrologic and reservoir operations models, Monterey and San Luis Obispo Counties, California2026-05-12sir20265005usgs
Top Elevation of Glacial Till and Thickness of the Big Sioux Aquifer Delineated From Electrical Resistivity Tomography Surveys Near Sioux Falls, South Dakota, 2022 and 20252026-05-12sir20265023usgs
Simulation of groundwater flow to evaluate hydrogeologic controls on a PFAS plume, Coakley Landfill Superfund site, Rockingham County, New Hampshire2026-05-11sir20265008usgs
Hydrogeologic framework and conceptual groundwater-flow model of the panhandle and northwest parts of the High Plains (Ogallala) aquifer in Oklahoma, 1998–20222026-05-11sir20265009usgs
Water use in Louisiana, 20202026-05-07sir20265135usgs
Shallow hydrogeologic framework of the Tully Valley mudboil area, Onondaga County, New York2026-04-29sir20265129usgs
Hydrologic investigation of water level fluctuations at Moreau Lake, Moreau Lake State Park, town of Moreau, New York2026-04-29sir20265132usgs
Assessment of groundwater quantity and quality contributions to Lake Huron2026-04-20sir20265136usgs
Escherichia coli monitoring and assessment in 2022 and 2023 after beach restoration at Lake St. Clair Metropark Beach, Macomb County, Michigan2026-04-09sir20265134usgs
Arsenic and isotope concentrations in the lower Platte River valley of eastern Nebraska, early 1970s to 20232026-04-09sir20265138usgs
Ungulate migrations of the Western United States, volume 62026-03-25sir20265123usgs
A three-dimensional geologic framework model of the northern Great Plains region of Montana, North Dakota, South Dakota, and Wyoming, USA2026-03-18sir20265127usgs
Stream sediment sources in Medicine Creek, northern Missouri and southern Iowa2026-03-02sir20265121usgs

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