Geology topics

Research about United States

Source-linked reports with geographic coverage including United States.

At least 19 recordsLinked to original sources

USGS2026

Characterization of subsurface groundwater pathways from treated wastewater effluent infiltration along the South Rim of Grand Canyon National Park, Arizona, USA

Recharge of treated wastewater to the environment is increasingly becoming a component of water resources management, especially in water-limited areas such as the Grand Canyon. Treated wastewater from the Grand Canyon South Rim Wastewater Treatment Plant has been discharged to a dry wash located along the surface expression of a fault for decades, but the fate of the wastewater is unclear. Previous research suggested possible connections between the treated wastewater discharge sites and springs along the South Rim of Grand Canyon, particularly Monument spring. Additional investigations presented in this report add further evidence to the connection between the wastewater and Monument spring, utilizing per- and polyfluoroalkyl substances, artificial sweeteners, and stable isotopes of water. A dye trace established the first direct connection between wastewater and Monument spring where the dye added to treated wastewater took about 4–6 months to move through the subsurface and was detectable for 5 months. The persistence of wastewater tracers over time and the timing of dye movement suggests a fast subsurface flow pathway. On the basis of geologic observations of faults and jointing, groundwater flow follows a possible combination of karst and other structural pathways. The dye and wastewater tracers were monitored at other springs along the South Rim of Grand Canyon and the combination of repeated dye detections and multiple wastewater tracers were only found at Monument spring. Multiple lines of evidence provide a robust tracer suite to support evidence of structural/karst controls on preferential flowpaths; faults alone are unlikely to explain the flow pathway.

Arizona↗

USGS2026

Groundwater nutrient contributions to surface water in the upper Maumee River basin

Harmful algal blooms triggered by nutrient loading have negatively affected Lake Erie water quality for decades, but the role groundwater plays in transporting nutrients to tributary streams is unclear. Here, we apply a multi-scale approach to investigate groundwater nitrogen (N) and phosphorus (P) dynamics at the field scale, along a groundwater flow path, and at the Maumee River basin scale. Unsaturated zone monitoring indicates that macropore flow is the primary mechanism for N and P leaching with nitrate and orthophosphate (OP) concentrations from macropore samplers more than double those from soil-matrix samplers. Shallow (< 4.5 m) groundwater nitrate concentrations indicate the timing of saturated-zone nitrate fluxes is crop dependent with more nitrate mobilized during the maize growing season whereas concentrations below soybeans can remain elevated (> 3 mg/L) through winter months. A three-end-member hydrograph analysis for the upper Maumee River basin indicates that tile drains transport most subsurface N and P with greater than 15,000 kg per day of nitrate transported between January and May. Orthophosphate concentrations in tile drainage at an edge-of-field site correlate well with concentrations in a nearby tributary of the Maumee River. While runoff is the dominant source of OP loading, tile drainage and groundwater discharge contributed an estimated 36% of OP load during a 2018–2022 analysis period with most subsurface loading occurring between January and March. These findings highlight how best management practices (such as cover crops and tile drainage control structures) can be used to help limit leaching and tile effluent during the nongrowing season.

Indiana↗

USGS2026

EMIT reveals elevated calcite signatures in shorelines of Lake Powell and Lake Mead exposed by drought and Colorado River management

Nearly half of Earth’s seasonal freshwater storage variability occurs in human-managed reservoirs, resulting in large areas of reservoir-bed that are episodically inundated or subaerially exposed. Here we use hyperspectral data from NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) mission to map calcite mineral assemblages across exposed surfaces in two large U.S. reservoirs, Lake Mead and Lake Powell. Results show distinct patterns in the occurrence of carbonate, clay, and mica minerals. Reservoir-deposited sediments exhibited significantly higher calcite proportions than adjacent, lithologically similar, non-inundated terrestrial surfaces. These differences likely reflect hydrologically-driven calcite precipitation, wherein warm, clear, productive reservoir waters drive calcium carbonate out of solution. We also detect reductions in calcite proportions in areas of the shoreline disturbed by human recreation. EMIT's imaging capabilities enable rapid, high-resolution mineralogical inventories across vast areas where field sampling is infeasible. We find EMIT is a scalable tool for monitoring geochemical changes associated with large water level fluctuations.

Arizona, Nevada, Utah↗

USGS2026

Drivers of ecosystem metabolism in an anthropogenically modified delta

Estuaries are under threat globally from a wide range of stressors, with rates of ecosystem metabolism – respiration (R), gross primary production (GPP), and net ecosystem metabolism (NEM) – representing a way for resource managers to quantify their impacts. In this study, we assessed how natural and anthropogenic stressors have altered metabolism within the extensively modified Sacramento-San Joaquin Delta (“Delta”) in California, USA. Metabolism was estimated using a diel open-water technique utilizing dissolved oxygen measurements from a high frequency (15 min) water quality monitoring array, and spanned 6 sites across 11 years (2014–2025). Our analyses were driven by a conceptual model of Delta carbon (C) cycling focused on 1) Invasive aquatic vegetation (IAV), 2) Phytoplankton, 3) Wastewater treatment plant (WWTP) upgrades, 4) Large-scale flow alterations, and 5) Wet vs. dry years. We found that allochthonous C fuels net heterotrophy in the outer riverine sections of the Delta, while the heavily vegetated central Delta produces autochthonous C remineralized elsewhere in the system. IAV were the dominant primary producers, with low phytoplankton production except during a historic bloom. WWTP upgrades imparted negligible changes to metabolism, with low chlorophyll a (< 5 µg L −1 ) both before and after. Introduction of a flow barrier – a management response to drought – hydrodynamically isolated deep-water channels from nearby shallow areas, resulting in decreased metabolism indicative of changes to C transport. Contrary to past research, low rainfall years were associated with increased metabolism. This study demonstrates how multi-sensor arrays can be used to quantify ecosystem responses to major environmental stressors.

California↗

USGS2026

Phase evolution and elemental partitioning in impact melts from Meteor Crater, Arizona

The impact of the Canyon Diablo iron meteorite in Arizona ∼61,000 years ago resulted in partial vaporization of the meteorite and target rocks, producing a vapor plume and melt particles with taenite, olivine and clinopyroxene in glassy matrix. The resulting Meteor Crater is ∼1.2 km in diameter and ∼200 m deep. Although the crater has been the natural laboratory for impact cratering, the microstructure and composition of its impact-melt particles remain poorly studied. Here microstructure and composition were investigated using optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron backscatter diffraction, and synchrotron microdiffraction on particles collected from the ejecta blanket to reconstruct their temporal and mineralogical evolution during ultrafast quenching and to explore how mafic minerals form from sedimentary-derived melts. Elemental mapping reveals complex chemical partitioning among glass and mafic phases. Formation of Fe-Ni globules with face-centered cubic (fcc) taenite indicates oxygen fugacity well below atmospheric in the vapor cloud. During rapid cooling, skeletal olivine crystallized, followed by nucleation of clinopyroxenes to form spherical clusters. The glassy matrix contains two glasses separated by sharp boundaries, likely representing immiscible melts derived from different lithologies. The hot particles were deposited on the surface among quartz- and dolomite-rich ejecta, followed by post-depositional precipitation of calcite and barite within glassy nodules. The results demonstrate that mafic minerals can crystallize from melts derived largely from sedimentary target rocks, with Fe supplied by the impactor, and that elemental partitioning and mineral textures record strong disequilibrium crystallization during rapid cooling.

Arizona↗

USGS2026

Map depicting locations susceptible to landslide hazards triggered by prolonged intense rainfall, Utuado Municipio, Puerto Rico

Introduction Landslides commonly occur in Puerto Rico during or soon after rainstorms with prolonged intense rainfall. Rainfall-triggered landslides present significant hazards to the built environment and human safety (for example, Jibson, 1986; Larsen and Torres Sanchez, 1992; Bessette-Kirton and others, 2019a). These hazards were illustrated during September 2017 (Hughes and others, 2019) when Hurricane María triggered more than 70,000 landslides across Puerto Rico (fig. 1), causing loss of life and widespread destruction (figs. 2–4). In Utuado Municipio, about 18,000 landslides were observed after Hurricane María (Hughes and others, 2019). Most intense rainfall-triggered landslides in Puerto Rico occur in soil overlying bedrock and travel downslope from where they initiate (for example, Jibson, 1986; Bessette-Kirton and others, 2019a, 2020). Hazards to human life and infrastructure can differ substantially between where landslides initiate and where they travel. At landslide initiation locations, the ground breaks up (fails) as it moves downslope, removing support for buildings, roadways, and other structures located upon the landslides (fig. 3A, B). This ground failure often causes structures to collapse and suffer severe damage or complete destruction, rendering building occupants at extreme risk. Roadways and other vital infrastructure, such as water, power, and communication lines, are often severed. During intense rainfall events, landslide initiation and movement downslope can occur in seconds to hours. Downslope from where they initiate, landslides in Puerto Rico often move very rapidly (faster than a person can walk or run) and can impact and destroy or fill structures with mud and debris (fig. 4) as well as bury roadways (fig. 3A, C). Moving landslides present extreme hazards to human safety; some fatalities during Hurricane María resulted from mud and debris that flowed through windows and doors of a home and buried occupants. Many landslides in Puerto Rico become fast-moving liquefied masses (debris flows), which are especially common in channels where they can quickly travel kilometers downstream. Multiple debris flows may occur in a channel during a single rainstorm (some channels experienced more than 50 debris flows during Hurricane María; Bessette-Kirton and others [2020] ). This hazard map separately depicts locations and the relative likelihood of where landslides may initiate, where they may move downslope, and where channelized debris flows may travel during or soon after intense rainfall like that during Hurricane María. An estimated average of 399 millimeters of rainfall fell across Utuado during September 19–21, 2017 (Ramos-Scharrón and Arima, 2019). Lower rainfall amounts, durations, and intensities also trigger landsliding in Puerto Rico, although landslides and debris flows become more numerous as rainfall intensities, durations, and cumulative amounts increase. The map does not show potential landslide locations in the karst terrain of northern Utuado (Bawiec, 1999) because Hurricane María-induced landslides were very sparse in this region (Hughes and others, 2019; Baxstrom and others, 2021a), even though rainfall amounts were similar to those in other parts of Utuado. Based on data from Hughes and others (2019), landslides were about 10 times more likely to occur outside of the karst terrane than within it, and our preliminary analyses indicated relatively low susceptibility to rainfall-induced landslide hazards within the karst. Landslide-prone soils appear to be poorly developed on the very steep slopes present in the karst region, where weathering by dissolution appears to dominate.

Puerto Rico, Utuado Municipio↗

USGS2026

Map depicting locations susceptible to landslide hazards triggered by prolonged intense rainfall, Naranjito Municipio, Puerto Rico

Introduction Landslides commonly occur in Puerto Rico during or soon after rainstorms with prolonged intense rainfall. Rainfall-triggered landslides present significant hazards to the built environment and human safety (for example, Jibson, 1986; Larsen and Torres Sanchez, 1992; Bessette-Kirton and others, 2019a). These hazards were illustrated during September 2017 (Hughes and others, 2019), when Hurricane María triggered more than 70,000 landslides across Puerto Rico (fig. 1), causing loss of life and widespread destruction (figs. 2–4). In Naranjito Municipio, about 2,000 landslides were observed after Hurricane María (Hughes and others, 2019). Most intense-rainfall-triggered landslides in Puerto Rico occur in soil overlying bedrock and travel downslope from where they initiated (for example, Jibson, 1986; Bessette-Kirton and others, 2019a; 2020). Hazards to human life and infrastructure can differ substantially between where landslides initiate and where they travel. At landslide initiation locations, the ground breaks up (fails) as it moves downslope, removing support for buildings, roadways, and other structures located upon the landslides (figs. 3B, 4A, B). This ground failure often causes structures to collapse and suffer severe damage or complete destruction, rendering building occupants at extreme risk. Roadways and other vital infrastructure, such as water, power, and communication lines are often severed. During intense rainfall events, landslide initiation and movement downslope can occur in seconds to hours. Downslope from where they initiate, landslides in Puerto Rico often move, or runout, very rapidly (faster than a person can walk or run) and can impact and destroy or fill structures with mud and debris (figs. 3A, 4A, C) as well as bury roadways (fig. 4A). Moving landslides present extreme hazards to human safety; some fatalities during Hurricane María resulted from mud and debris that flowed through windows and doors of a home and buried occupants. Many landslides in Puerto Rico become fast-moving debris flows, which are especially common in channels where they can quickly travel kilometers downstream. Multiple debris flows may occur in a channel during a single rainstorm (some channels experienced more than 50 debris flows during Hurricane María; Bessette-Kirton and others, 2020). This map separately depicts locations and the relative likelihood of where landslides may initiate, where they may move downslope, and where channelized debris flows may travel during or soon after intense rainfall like that during Hurricane María. An estimated average of 529 millimeters of rainfall fell across Naranjito during September 19–21, 2017 (Ramos-Scharrón and Arima, 2019). Lower rainfall amounts, durations, and intensities also trigger landsliding in Puerto Rico, although landslides and debris flows become more numerous as rainfall intensities, durations, and cumulative amounts increase.

Naranjito Municipio, Puerto Rico↗

USGS2026

Map depicting locations susceptible to landslide hazards triggered by prolonged intense rainfall, Lares Municipio, Puerto Rico

Introduction Landslides commonly occur in Puerto Rico during or soon after rainstorms with prolonged intense rainfall. Rainfall-triggered landslides present significant hazards to the built environment and human safety (for example, Jibson, 1986; Larsen and Torres Sanchez, 1992; Bessette-Kirton and others, 2019a). These hazards were illustrated during September 2017 (Hughes and others, 2019), when Hurricane María triggered more than 70,000 landslides across Puerto Rico (fig. 1), causing loss of life and widespread destruction (figs. 2 and 3). In Lares Municipio, about 3,500 landslides were observed after Hurricane María (Hughes and others, 2019). Most intense-rainfall-triggered landslides in Puerto Rico occur in soil overlying bedrock and travel downslope from where they initiated (for example, Jibson, 1986; Bessette-Kirton and others, 2019a; 2020). Hazards to human life and infrastructure can differ substantially between where landslides initiate and where they travel. At landslide initiation locations, the ground breaks up (fails) as it moves downslope, removing support for buildings, roadways, and other structures located upon the landslides (figs. 2, 3A, B). This ground failure often causes structures to collapse and suffer severe damage or complete destruction, rendering building occupants at extreme risk. Roadways and other vital infrastructure, such as water, power, and communication lines are often severed. During intense rainfall events, landslide initiation and movement downslope can occur in seconds to hours. Downslope from where they initiate, landslides in Puerto Rico often move, or runout, very rapidly (faster than a person can walk or run) and can impact and destroy or fill structures with mud and debris (figs. 3A, C) as well as bury roadways (fig. 3A). Moving landslides present extreme hazards to human safety; some fatalities during Hurricane María resulted from mud and debris that flowed through windows and doors of a home and buried occupants. Many landslides in Puerto Rico become fast-moving debris flows, which are especially common in channels where they can quickly travel kilometers downstream. Multiple debris flows may occur in a channel during a single rainstorm (some channels experienced more than 50 debris flows during Hurricane María; Bessette-Kirton and others, 2020). This map separately depicts locations and the relative likelihood of where landslides may initiate, where they may move downslope, and where channelized debris flows may travel during or soon after intense rainfall like that during Hurricane María. An estimated average of 256 millimeters of rainfall fell across Lares during September 19–21, 2017 (Ramos-Scharrón and Arima, 2019). Lower rainfall amounts, durations, and intensities also trigger landsliding in Puerto Rico, although landslides and debris flows become more numerous as rainfall intensities, durations, and cumulative amounts increase. The map does not show potential landslide locations in the karst terrain of northern Lares (Bawiec, 1999) because Hurricane María-induced landslides were very sparse in this region (Hughes and others, 2019; Baxstrom and others, 2021a), even though rainfall amounts were similar to those in other parts of Lares. Based on data from Hughes and others (2019), landslides were about ten times more likely to occur outside of the karst terrane than within it, and our preliminary analyses indicate relatively low susceptibility to rainfall-induced landslide hazards within the karst. Landslide-prone soils appear to be poorly developed on the very steep slopes present in the karst region, where weathering by dissolution appears to dominate.

Lares Municipio, Puerto Rico↗

USGS2026

Geophysical insights into Kīlauea’s eruptive reawakening after its 2018 eruption and caldera collapse

A little more than two years after the destructive 2018 lower East Rift Zone eruption and summit collapse ended, renewed volcanic activity began at Kīlauea volcano, Hawaiʻi. During 2020–2025, activity at the volcano included six eruptions in the summit caldera, one in the Southwest Rift Zone, and one in the middle East Rift Zone, as well as multiple non-eruptive intrusions in all three locations. We categorize the volcano’s activity post-2018 into four phases based on eruption locations and style, as well as patterns of magma storage and migration inferred from geophysical data. In some cases, these observations illuminated parts of the volcano’s magmatic system for the first time since the advent of modern geophysical monitoring—particularly deformation datasets that include tilt, continuous GNSS, and InSAR. Analyses of these geodetic data and complementary seismic, geological, and geochemical observations provide an opportunity to explore summit and rift zone connectivity, rift-zone magma storage conditions, the variable geophysical manifestations of eruption onsets, magma-fault interactions, and other long-standing questions associated with eruptions and intrusions at Kīlauea.

Hawaii↗

USGS2026

Highly pathogenic H5N1 avian influenza infection and exposure in waterfowl and waterbirds of the Sacramento National Wildlife Refuge Complex, 2022-2025

The introduction of clade 2.3.4.4b highly pathogenic avian influenza (HPAI) H5N1 into North America in 2021 marked a significant shift in disease dynamics for wild waterfowl populations. To assess infection and seroprevalence trends following this incursion, we leveraged ongoing capture efforts at the Sacramento National Wildlife Refuge Complex between October 2022 and July 2025 to conduct sampling for HPAI H5N1 prevalence and seroprevalence. Our efforts resulted in the analysis of 384 swab and 204 sera samples from assorted waterfowl and waterbird species. HPAI H5N1 infection was confirmed in only three individuals (two Snow Geese and one Greater White-fronted Goose), all asymptomatic at capture. Antibodies to influenza A viruses (IAVs) were detected in all duck and goose species with the majority of positive samples also testing positive for antibodies to both H5 and N1, demonstrating a relatively high population level of previous exposure and likely immunity that aligns with previous findings in these species. This study also reports the first known observation of H5 antibodies in American Coot, though both overall IAV seroprevalence and H5 specific antibodies were notably lower than in sympatric waterfowl. This disparity suggests that American Coot may have lower susceptibility to infection or exhibit behavior that limits exposure compared to sympatric waterfowl. Together these results underscore the value of serologic surveillance as a supportive surveillance strategy to better inform potential management strategies related to HPAI H5N1 risk in wild birds.

California↗

USGS2026

Erupted volume during the 2014–2023 Semisopochnoi unrest and eruption constrained by multi-platform InSAR and volcanic gas observations

Volcano deformation data provide important constraints on magma dynamics during volcanic unrest and eruptions. From these observations, we can estimate subsurface pressure changes and relate them to volume change in the reservoir. However, because magma and rock are compressible, this volume change cannot be directly equated with eruptive volume. When we combine geodetic analyses with gas observations, petrologic constraints, volatile solubility modeling, and magma compressibility equations, however, we can estimate realistic lower and upper bounds of eruptive volume. Leveraging multi‐platform InSAR time series and satellite SO 2 data, we apply these methods to the 2014–2023 unrest and eruption of Semisopochnoi, Alaska. We find that this phreatomagmatic eruption sequence was fed by a spherical magma source at 6.5–7.5 km depth bsl, centered beneath the caldera, ∼5 km offset to the east from the vent. Volatile solubility modeling indicates that ∼50% of the initial dissolved CO 2 has exsolved at depths consistent with the geodetic source depth, increasing the magma compressibility. Combining geodetic model constraints with SO 2 observations, petrologic constraints, solubility models, and magma compressibility findings yields 12–32 Mm 3 as the most‐likely juvenile, dense‐rock equivalent eruptive volume, with a best estimate of 20 Mm 3 . Stress change modeling suggests that the local stress field encouraged conduit formation west of the pre‐eruptive inflation center, and that the 2014 M7.9 Rat Island earthquake, ∼65 km to the west of Semisopochnoi, reduced the compressive stress underneath the volcano, supporting prolonged eruptive activity.

Alaska↗

USGS2026

Atlas of pollen and spores from forests and wetlands in the mid-Atlantic Coastal Plain, USA

This atlas includes descriptions and illustrations of pollen and spores from plant species found in the mid-Atlantic Coastal Plain of the United States of America, with a focus on taxa that grow in or near riparian wetlands. We include light micrographs and detailed descriptions of 141 species spanning 106 genera and 69 families. This atlas was compiled to facilitate the identification of palynomorphs from sedimentary archives in the mid-Atlantic region. We include both wetland taxa and those from surrounding uplands that may be deposited in wetland sediments.

North Carolina, South Carolina, Virginia↗

USGS2026

Exploring future ecogeomorphic state transitions of an undeveloped barrier island: Multidecadal model projections for North Core Banks, NC, USA

Ecogeomorphic state transitions in coastal barrier systems will be impacted and likely amplified by projected accelerated sea-level rise and enhanced storm intensity over the next several decades. When, where, and how these transitions will take place remain uncertain and complex, yet are of primary interest to coastal managers looking to prepare for future changes. Here, we apply the new Mesoscale Explicit Ecogeomorphic Barrier model to generate probabilistic projections of future ecogeomorphic state transitions up to year 2050 for the undeveloped North Core Banks (NCB), North Carolina, United States. In our full probabilistic projection, which accounts for stochasticity from uncertainty in sea-level rise and high-water event (HWE) projections, loss of barrier interior to passive sea-level rise submergence dominates ecogeomorphic state transitions, suggesting that the biggest threat to many undeveloped barriers in the next several decades will come from the back-barrier rather than ocean-side. Additionally, this projection suggests that dune and unvegetated interior states are most volatile, with the intensity of state transitions varying significantly alongshore. In projections simulating a range of deterministic sea-level rise rates, higher rates enhance: overwash frequency; loss of beach and dune states; and interior submergence. We also find that state transitions are less sensitive to HWE intensity than sea-level rise, and that more frequent, moderate HWEs—rather than the largest events—may be the principal drivers of mesoscale ecogeomorphic state change. Our projections highlight important future mesoscale trends of ecogeomorphic state transitions for NCB that are likely relevant to other stable, sediment-rich barrier systems of U.S. coastlines.

North Carolina↗

USGS2026

Big data for small streams: Leveraging a coarse national model to enhance fine-resolution stream temperature predictions

Predictive stream temperature models are commonly used to address spatial and temporal gaps in observational data because stream temperature information is essential for environmental management decisions. National models capture broad patterns driven by climate, topography, and seasonality, but often lack the spatial resolution to simulate fine-scale variation in groundwater discharge, riparian shading, or tributary inflows. In contrast, watershed models may simulate finer-resolution patterns but miss regional drivers or be limited by scarcity of observations. To generate watershed-extent, fine-resolution stream temperature predictions, we developed 18 multiscale machine-learning models that leverage (a) a broad-extent, coarse-resolution stream temperature model and (b) finer-resolution observations and predictor data. The coarse-resolution model simulates daily stream temperature across the conterminous United States on the National Hydrologic Geospatial Fabric (13.7 km median reach length; 865,364 km total). The fine-resolution models simulate daily stream temperature on the National Hydrography Dataset Plus version 2 (1.5 km median; 5,192,808 km total). We compared multiscale models to seven purely broad- (national) or watershed-extent models, testing them in eight watersheds (436–985 km 2 ) with differing hydrologic settings and under realistic data availability scenarios. Especially when observations within a watershed were scarce, multiscale models generated more accurate predictions than national or watershed-specific models. A recurrent graph convolution neural network pretrained on coarse predictions and fine-tuned on watershed-specific observations was most accurate across watersheds and data scenarios. These results highlight that leveraging both coarse, national results and watershed-specific data can increase model accuracies, particularly when observations within a watershed are spatially or temporally limited.

Water Resources Research↗

USGS2026

The flip side of destructive wildfires: A water supply buffer to climate change

Wet to dry climate extremes in California have directly or indirectly impacted droughts, wildfires, and floods, resulting in costly damage. Reservoirs in California were built to store snowpack into the summer and provide multiple benefits in the state: they offer municipal and agricultural water resources during the dry season and prevent flooding downstream. The upper Feather River watershed, which drains 9300 square kilometers (km 2 ) into Lake Oroville, provides water to over 27 million people and 3000 km 2 of farmland. The North Complex Fire in 2020 and the Dixie and Sugar Fires in 2021 burned over 50% of the watershed, and their long-term impact on the upper Feather River water supply was previously unknown. This study quantified post-wildfire (postfire) changes in plant water use, soil moisture, and streamflow due to changes in vegetation using a physically based water balance model. Long-term trends revealed decreases in annual precipitation and mid- to high-elevation snowpack in this watershed from 1981 to 2020. Due to changes in vegetation, annual postfire streamflow at Feather River at Oroville increased by 22%, 32%, and 16% while summer baseflows increased by 5%, 12%, and 2% in water years (WYs) 2022 through 2024, respectively. Larger increases in streamflow occurred during WY 2023, an extremely wet year relative to the other years, highlighting the challenges in quantifying and managing hydrologic systems with naturally high interannual variability. Seasonal soil moisture increased by up to 34% depending on the location, predominantly in fall and summer postfire. Despite observed historical decreases in precipitation and snowpack, changes in vegetation due to wildfires or other disturbances may increase water availability, and continued management of mixed-conifer forests (i.e. thinning and controlled burns) may help offset future reduced precipitation and snowpack and therefore increase water supply resilience.

Callfiornia↗

USGS2026

MusselFinder: Automated dreissenid mussel density estimation via robotic benthic imaging

Despite the widespread need to map the abundance of invasive quagga and zebr mussels ( Dreissena spp.) in lakes and reservoirs worldwide, current methods remain limited by data collection and analysis bottlenecks. Autonomous underwater vehicles (AUVs) combined with machine learning (ML) offer a scalable remote sensing approach for estimating mussel density (individuals m −2 ) across large spatial domains and a range of habitats that are difficult to sample with current techniques. We present MusselFinder: a deep neural network (DNN)-based pipeline that detects and enumerates live mussels in AUV-collected benthic images. MusselFinder estimates live mussel percent cover and density in nadir monocular images captured at known altitudes above the lakebed. In images of suitable clarity, MusselFinder achieved strong pixel-level localization (mussel-class Intersection over Union [IoU] > 0.76) and density prediction (log-density R 2 = 0.79–0.95) over a variety of bottom types. AUV-based image acquisition is more than three orders of magnitude faster than physical sampling by divers or ponar grabs, and DNN-based analysis can proceed at rates comparable to image acquisition. We used MusselFinder to analyze over 50,000 spatially referenced images at a spawning reef in Lake Michigan, representing a shift from small-scale, diver-collected datasets to large-scale monitoring in unconstrained environments. The method can be adapted to new imaging conditions using a modest training set and a user-friendly point-labeling technique, supporting broader-scale monitoring of one of the world's most invasive invertebrates.

Illinois, Michigan↗

USGS2026

A spatial analysis of the groundwater emergence flood hazard in Long Island, New York, and coastal areas surrounding Long Island Sound in New York, Connecticut, and Rhode Island

Long Island, New York, and nearby coastal areas surrounding Long Island Sound are densely populated and, like other coastal areas, are susceptible to flooding from several potential sources, including stormwater from precipitation events, tidal flooding and storm surge, and groundwater emergence flooding. Groundwater emergence fooding refers to the intersection of a rising water table with land surface or critical infrastructure. Many studies of flood drivers either neglect or only briefly discuss how shallow groundwater conditions may contribute to or exacerbate flood conditions. As a part of a comprehensive study of compound flood hazards in the coastal areas of Long Island and Long Island Sound, a spatial analysis was completed by the U.S. Geological Survey, in cooperation with the Environmental Protection Agency’s Long Island Sound Partnership, formerly called the Long Island Sound Study, using available regional datasets to characterize the potential hazard for groundwater emergence flooding. The approximately 3,100 square mile study area was subdivided into 11,407 grid cells that were 900 meters by 900 meters (approximately 3,000 feet by 3,000 feet), for the purpose of integrating the spatial datasets to calculate and map the groundwater emergence flood hazard. The depth to the water table, hydrologic soil groups, and National Land Cover Database were harmonized to the common grid. A groundwater emergence flood hazard score was calculated for each grid cell for current average conditions following a set of rules accounting for the depth to the water table and the percentage of area within each cell with slow infiltrating soils. A scenario with a higher sea-level position was also calculated for the Long Island part of the study area. The calculated groundwater emergence flood hazard score was reviewed in conjunction with the National Land Cover Database to identify developed areas and associated infrastructure that may be at risk of potential groundwater emergence flooding. Study results indicate that the groundwater emergence flood hazard is highest in coastal areas and near surface water where the water table is close to ground surface. Inland areas away from surface waterbodies are not likely to be exposed to groundwater emergence flooding. For Long Island, in the scenario with higher sea-level position, a greater groundwater emergence flood hazard is calculated for some locations closer to the coast and where land is submerged. Away from the coast and surface-water drainage, the groundwater emergence flood hazard is similar between the current average sea-level condition and the higher sea-level position scenario.

Connecticut, New York, Rhode Island↗

USGS2026

Streamflow assessment of Birch Creek, southern boundary of the Blackfeet Indian Reservation, Pondera County, northwestern Montana—Synoptic and continuous streamflow measurements through 2022

The U.S. Geological Survey, in cooperation with the Blackfeet Water Department, performed this study to assist water-resource managers in understanding and quantifying irrigation diversions, instream flows, and the spatial and temporal streamflow dynamics of Birch Creek in northwestern Montana. Birch Creek forms the southernmost boundary of the Blackfeet Indian Reservation and is highly valued culturally as an aquatic life and wildlife resource and as a principal source of water for irrigation. The study area included Birch Creek from Swift Dam to 53.3 miles downstream just above its confluence with the Two Medicine River. The study period was calendar year 2022, but selected historical information was also included in the study. Birch Creek streamflow originates through releases from Swift Reservoir, with the largest releases typically occurring during the irrigation season (May–October) to primarily meet the needs of downstream irrigators. This study included the compilation and collection of (1) continuous streamflow measured at streamgages installed for this study, (2) instantaneous streamflow measurements made during four synoptic events, and (3) reported daily values of Swift Reservoir outflow and irrigation diversions. Continuous streamflow data were available from two U.S. Geological Survey streamgages: Birch Creek below Heart Butte Road, near Heart Butte, Montana (upper streamgage; station 06094900), at river mile 12.9 and Birch Creek at Bullhead Bridge near Valier, Mont. (lower streamgage; station 06098120), at river mile 53.3. The upper streamgage (station 06094900) was primarily affected by the regulated releases from Swift Dam with daily mean streamflow typically slightly higher than the reported Swift Reservoir outflows. Daily mean streamflow ranged from 9.87 cubic feet per second (ft 3 /s) (November 18, 2022) to 640 ft 3 /s (June 22, 2022) during September 16, 2021–December 31, 2022. The mean annual streamflow was 122 ft 3 /s in water year 2022 (a water year is the 12-month period from October 1 to September 30 and is designated by the year in which it ends), about 13 percent greater than the mean annual reported Swift Reservoir outflows. The lower streamgage (station 06098120) was downstream from all major tributaries and diversions within the Birch Creek drainage basin. Daily mean streamflow ranged from 6.02 ft 3 /s (September 8, 2022) to 95.0 ft 3 /s (June 5, 2021) during August 26, 2020–December 31, 2022. Mean annual streamflow was 27.8 ft 3 /s for water year 2022. Flows at the lower streamgage (station 06098120) were typically lower than at the upper streamgage (station 06094900) from late April to early October, whereas flows from early October to late spring were similar to or greater than those at the upper streamgage. The upper streamgage had a total streamflow volume of 87,960 acre-feet (acre-ft) for water year 2022, whereas the lower streamgage had a total streamflow of 20,357 acre-ft. A net volume of about 67,603 acre-ft was removed from Birch Creek through diversions, losses to groundwater, and evapotranspiration along that reach during water year 2022. Most of the changes in main-stem streamflow could be accounted for by the tributary inflows or diversion outflows. The most dynamic streamflow gains and losses occurred along the upper few miles of Birch Creek. Streamflow was consistently lost to the groundwater system immediately below Swift Dam and then returned to levels that slightly exceeded the outflow at the dam near river mile 11.0. The overall net gains for the entire 53.3-mile study reach ranged from 15.5 to 42.6 ft 3 /s among the synoptic events. On several occasions, streamflow fell below minimum instream flow conditions specified in the Blackfeet Compact (water rights compact among the Blackfeet Tribe, State of Montana, and United States), which are subject to a 15-year deferral period (until June 12, 2033). Notably, a section of Birch Creek immediately downstream from Swift Dam was completely dry during the October 18, 2022, synoptic event.

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