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At least 1,459 records · Page 81Linked to original sources
USGS2026

Differentiating persistent and intermittent euxinia from the molecular derivatives of green sulfur bacteria carotenoids

Green sulfur bacteria biomarkers that indicate euxinia within the photic zone sometimes co-occur with evidence of contradictory depositional redox conditions, such as oxygen-requiring fossils or bioturbation. Intermittent euxinia may explain this apparent contradiction, and recent studies of modern environments show that green sulfur bacteria dwell in transiently euxinic settings. As a result, new approaches are needed to distinguish green sulfur bacteria biomarkers indicative of persistent versus intermittent euxina in ancient sedimentary samples, which this study addresses by investigating how the distribution of isorenieratene derivatives relates to depositional redox conditions. To accomplish this objective, this study focuses on two drill cores through the Upper Cretaceous Mowry Shale and the Eagle Ford Group. These drill cores are comparably thermally immature according to vitrinite reflectance data, and these formations in these cores capture a spectrum of depositional redox conditions according to multiple organic and inorganic proxies, including newly acquired iron speciation and kerogen organic sulfur data. The results presented here reveal that higher molecular weight diagenetic products of isorenieratene are preferentially preserved under persistent euxinia compared to intermittently euxinic intervals that contain isorenieratene derivatives that are shifted to lower molecular weights. Further, the total inventory of aromatic carotenoid diagenetic products contains features that can be used to identify green sulfur bacteria biomarkers from reworked petrogenic sources. Accordingly, the diagenetic fate of isorenieratene and the distribution of its diagenetic products distinguish persistent versus intermittent euxinia, which can be used to sharpen our evaluation of euxinia in the geologic record.

Geochemica et Cosmochimica Acta↗
USGS2026

Millennial-scale climatic and cultural impacts on vegetation and fire at the southern edge of the Rocky Mountains, USA

Mountain forests and woodlands in semiarid regions of the world are threatened by climatic change and other human impacts. In the southwestern USA, climate and culturally driven changes to the structure and fire regimes of dry coniferous forests over recent centuries are well documented by tree-ring archives. However, the roles of climate and people as drivers of millennial-scale changes are less understood. We present a new record of vegetation dynamics and regional fire activity inferred from pollen, microscopic charcoal, and sediment geochemistry from Santa Fe Lake, NM (3532 m a.s.l.), the southernmost natural lake in the Rocky Mountains. Declining elemental intensities (e.g., Ti, Fe, Si) record local deglaciation after 14,000 cal yr BP followed by upslope expansion of trees indicated by increasing Pinus and Picea pollen percentages as the climate warmed during the Late Glacial. Cool, dry growing seasons probably limited the establishment of dense forests until after 12,200 cal yr BP when we hypothesize that Pinus ponderosa (ponderosa pine) expanded regionally (i.e., within 10–100 km) due to continued warming and a possible increase in monsoonal precipitation. Subalpine forests established near Santa Fe Lake by 10,300 cal yr BP as indicated by abundant conifer stomates and increasing Picea and Pinus aristata pollen percentages, which are highest after 5100 cal yr BP. Increasing Juniperus -type, Quercus , and Pinus edulis -type pollen record changes in vegetation belts at lower elevations after 10,300 cal yr BP. Maize pollen, an unambiguous indicator of Puebloan agriculture, first appears at 800 cal yr BP (1150 cal yr CE) and is present through 1600 cal yr CE when Spanish colonization brought cultural upheaval and population loss to local indigenous communities. Regional fire activity, inferred from microscopic charcoal influx, remained relatively constant for most of our record. However, average microscopic charcoal influx more than doubled relative to the rest of the Holocene during the last 2000 years, with the highest influx after 1550 cal yr BP (400 cal yr CE). The increased influx of microscopic charcoal coincides with archaeological evidence for dramatic regional population growth in the northern Rio Grande region and probably reflects extensive cultural burning associated with the development of an agricultural economy. Although climate was an important driver of vegetation change and fire regimes in the mountains of the southwestern USA during the Holocene, our results suggest that human impacts on regional burning during the last 2000 years far exceeded earlier climate-driven variation.

Rocky Mountains↗
USGS2026

Thinking outside the rocks: Subsurface water storage, topography, and land cover are key modulators of large-scale riverine dissolved silicon dynamics

Riverine dissolved silicon (DSi) dynamics reflect integrated geologic, hydrologic, climatic, and ecological controls. We compiled annual DSi data for 337 rivers across four continents and trained interpretable machine-learning models to predict concentrations and yields from 28 watershed variables. Both models reproduced testing data ( R 2 = 0.85 for concentration and 0.96 for yield) and withheld-site validation ( R 2 = 0.91 and 0.93). Lithology, especially volcanic rock fraction, strongly controlled DSi while subsurface storage, topography, and land cover further shaped DSi dynamics. DSi concentrations and yields exhibited nonlinear responses to basin slope, recession-curve slope, proportion of open-water cover, and nutrient availability. Concentrations showed sharper threshold responses to hydrologic and biotic variables, whereas yields varied more gradually with climate and lithology. These results provide a framework for forecasting DSi under land cover and climate change and for embedding realistic, nonlinear processes in mechanistic models.

Geophysical Research Letters↗
USGS2026

Seasonal and decadal changes in winter body condition of four sympatric diving ducks

Winter body condition is an important driver of survival, reproductive output, and overall population health in waterfowl. Diving duck species use distinct habitats, exploit unique resources, and can collectively provide an integrated index of winter habitat quality. The San Francisco Bay (SFB) is the largest estuary on the west coast of North America, serving as critical wintering habitat for diving ducks in the Pacific Flyway. To evaluate the body condition of diving ducks after multiple decades of tidal habitat restoration in SFB, we compared structurally corrected measurements (annual and decadal) of total carcass lipid among canvasback ( Aythya valisineria ), greater scaup ( Aythya marila ), lesser scaup ( Aythya affinis ), and ruddy duck ( Oxyura jamaicensis ). We found greater and lesser scaup gained lipid reserves within the estuary prior to spring migration; however, canvasback and ruddy duck lipid levels declined throughout the winter and into the spring. Lipid loss over the wintering period could indicate a reduction in foraging resource availability, dietary shifts, or metabolic changes. These deficiencies could have negative cross-seasonal implications, as these species must accumulate resources outside of their wintering areas to fuel migration and reproduction. Lipid levels were elevated in lesser scaup collected in 2017-2019 compared to 1998-2000, while we found no decadal differences in lipid levels for canvasback or greater scaup. Our findings suggest tidal restoration in SFB, among other factors, may benefit some diving duck species.

California↗
USGS2026

Harvest of long-tailed ducks from an important hunting location on Lake Michigan

Annual waterfowl harvest in North America is estimated through a collaborative and strategic process, with federal harvest surveys the primary method of estimation. Sea duck hunters participating in federal harvest surveys represent a small proportion of the overall waterfowl hunting population, limiting the utility of harvest estimates for sea ducks. The long-tailed duck ( Clangula hyemalis ) is one such species. To partially address the paucity of long-tailed duck harvest survey information, we conducted in-person hunter surveys from 1 November through 4 December 2016 at a boat launch in Two Rivers, Wisconsin, USA (Lake Michigan), an important area for long-tailed duck harvest within the state. Hunters were present on 15 of 21 survey days, and we surveyed occupants of 62 individual hunting boats on 127 occasions. Long-tailed ducks were the most common (97%) of the 1,431 sea ducks reported harvested by hunters. Hunter harvest of long-tailed ducks averaged 3.8 (95% CI = 3.4, 4.1; range = 0–6) long-tailed ducks/hunter/day. We used count models to evaluate the effects of environmental variables on hunter participation and harvest of long-tailed ducks. Wave height was the most influential predictor variable for hunter participation; an information criterion-based best model (wave height + temperature) indicated that hunter participation decreased by 91.9% (95% CI = 79.3–97.1%) for each 1-m increase in wave height. Long-tailed duck harvest was positively associated with air temperature; the relationship indicated a 9.5% (95% CI = 6.2–12.9%) increase in long-tailed duck harvest with each degree increase in temperature. Our results contribute to the understanding of waterfowl hunter participation, hunter preferences, and harvest on Lake Michigan and can inform managers as they assess regulatory frameworks for sea duck hunting.

Wisconsin↗
USGS2026

Integrating fecal DNA and telemetry to estimate wildlife densities in anthropogenic landscapes

Density estimation is central to wildlife management efforts but can be challenging in anthropogenically-dominated landscapes due to small parcel sizes, access restrictions, and limited green space. Reliable density estimates are especially important for managing white-tailed deer ( Odocoileus virginianus ), whose high abundance in urbanized areas increases the need for accurate population assessments to guide management and reduce negative human–wildlife interactions. Herein, we evaluated (a) the use of a plot-based spatial capture-recapture sampling design to estimate deer density in developed landscapes and (b) if integrating telemetry data improved the precision or biological inferences of density estimates. We conducted fecal sampling at 2 study areas reflecting different characteristics of the urbanization gradient in Durham and eastern Orange counties, North Carolina: (1) rural (i.e., forested, large parcels) and (2) suburban (i.e., small parcels, limited continuous access, diversity of landscape features). We collected 223 fecal samples during a 3-week sampling period in July and September 2022, resulting in 157 individual deer detected (112 F:45 M). Rural densities were estimated at 54 deer/km 2 (95% CI = 35–84) and suburban densities at 75 deer/km 2 (95% CI = 48–117). Integrating telemetry data allowed estimation of sex-specific space use and densities, which were not possible from fecal data alone; however, precision of total density estimates was similar across integrated and fecal-only analyses. Overall, our results highlighted key trade-offs inherent to plot-based spatial capture-recapture in suburban landscapes, most notably low recapture rates, accessibility challenges to maintain optimal trap spacing, and the importance of considering auxiliary data streams as part of the study design.

North Carolina↗
USGS2026

Decadal trends and occurrence of geogenic constituents and mixtures in groundwater across the continental United States

Worldwide, about 50% of the population is served by groundwater-sourced drinking water. Numerous groundwater quality assessments have found that geogenic constituents are among the most common contaminants in drinking-water aquifers. Documenting changing groundwater quality is a crucial aspect of water availability assessments. We assess trends and occurrence of geogenic constituent concentrations in groundwater across the continental United States using 3 decades of data from the U.S. Geological Survey’s National Water Quality Network. Thousands of groundwater wells were grouped into agricultural, urban, or domestic supply network types. Although most networks and constituents had no statistically significant change in concentration, many had increasing concentration trends, elevated concentrations, or both. Lithium, sodium, radium, sulfate, and uranium had increasing trends in more than 10% of the study networks. Urban and domestic well networks had increasing lithium and sodium trends more often than agricultural networks. Manganese most commonly increased in domestic well networks; uranium more commonly increased in agricultural and urban networks. Elevated concentration mixtures were widespread, and mixture complexities appeared to increase over time. Our results indicate that more than 2.3 million domestic-well users may be affected by elevated concentrations of one or more geogenic constituents.

continental United States↗
USGS2026

What is the (real) rate of soil health practice adoption? Making sense of three data sources

Conservation stakeholders looking to quantify the impact of their investments to increase soil health practice adoption over time often face challenges in interpreting practice adoption data due to discrepancies in language and results among data sources. Similarly, efforts to estimate environmental outcomes of practice adoption, such as water quality and greenhouse gas emissions, can vary depending on different practice adoption input data. To help make sense of different adoption data sources, we compared county-level adoption data for winter cover crops (WCC), no-till (NT), and reduced tillage (RT) in three areas of the United States with contrasting climates and production systems: central Illinois (CIL), southern Illinois (SIL), and western New York (WNY). We analyzed data available during 2015 through 2022 from the Operational Tillage Information System (OpTIS, remote sensing), US Census of Agriculture (AgCensus, a farmer survey), and, specifically in Illinois, the Illinois Soil Conservation Transect Survey (Transect, a roadside survey). The magnitude of differences between the datasets depended on the practice and geographic location. For example, OpTIS and AgCensus tillage data were much more similar in Illinois (average difference of less than 4 percentage points) compared to New York (average differences of 20 percentage points). Similarly, there was less variability and smaller differences between OpTIS and AgCensus WCC data in Illinois compared to WNY. AgCensus tended to report lower WCC adoption for Illinois and greater adoption in WNY compared to OpTIS. All data sources agreed that the rate of change in tillage practices is slow (mainly –1% to 1%) and that adoption of WCC is low (assuming linear growth, it could take nearly a century to reach 50% WCC adoption in CIL). Differences among the datasets were attributed to definitional inconsistencies for RT and NT and how WCC data were acquired. For example, the AgCensus asks if a WCC was planted, whereas OpTIS and Transect evaluate the presence of a standing WCC. Data sources also reflect different time periods (calendar years or crop years) and types of cropland assessed (corn [ Zea mays L.], soybean [ Glycine max {L.} Merr.], or all cropland). We propose two recommendations to improve interpretation and consistency: (1) a working group to harmonize definitions and protocols and develop educational materials for data users, and (2) a research effort that integrates different adoption data types and produces publicly available adoption data at HUC-10 and county scales. Such activities could help improve data access and utility for evidence-based conservation decision-making and enhance the accuracy of environmental models that rely on adoption data as input.

Journal of Soil and Water Conservation↗
USGS2026

Latest Pleistocene to 19th-century earthquakes on bending-moment reverse faults of the Seattle fault zone, Washington

Fault-related folds and their associated secondary faults play a critical yet often underrecognized role in accommodating strain and generating earthquakes in active fold-and-thrust belts. In the Seattle fault zone (SFZ), Washington, USA, we present new paleoseismic, geomorphic, and geophysical evidence for late Pleistocene and Holocene earthquakes on shallow, south-dipping secondary faults—the Lytle Beach and Vasa Park faults—that lie within the hanging wall of the greater SFZ and are on trend with the primary, blind Blakely Harbor fault. Our data show that these structures have ruptured independently, producing localized uplift and deformation at the surface, with the most recent event (RH2) likely occurring in the early nineteenth century. While a temporal overlap between the late Pleistocene RH1 and VP1 earthquakes raises the possibility of a ≥35 km rupture along the Blakely Harbor fault, structural and temporal evidence instead supports independent rupture on individual faults related to folding. We interpret these faults as bending-moment reverse faults that formed within a synclinal hinge zone of the main fault, reflecting mechanical and kinematic influences of the broader fault system. Combined with prior studies, our findings indicate that faulting related to folding dominates the mode of strain release within the SFZ since the late Pleistocene with more frequent earthquake recurrence (∼350 yr) over the past ∼2500 yr.

Washington↗
USGS2026

Vegetation cover and composition in environments surrounding uranium mines in the Grand Canyon ecosystem, Northern Arizona

Mining uranium from breccia-pipe deposits in the greater Grand Canyon region has occurred since the mid-1900s. However, possible ecosystem contamination with harmful levels of radionuclides may have occurred due to mining activities in the 21st century. In response, a 20-year Federal moratorium on new mining claims in the Grand Canyon watershed was initiated in 2012, to allow time to evaluate the potential effects of uranium exploration and mining on human health, wildlife, and water resources. This moratorium, nor the 2023 designation of the “Baaj Nwaavjo I’tah Kukveni–Ancestral Footprints of the Grand Canyon National Monument,” precludes operation or development of mining claims predating 2012. Vegetation is a core ecosystem component that may be affected by uranium mining (for instance, through uptake and storage of radionuclides from the air or soil) or may act as a vector of exposure to wildlife, livestock, and humans (for instance, via their consumption of contaminated plant tissues). To provide baseline information about the plant communities associated with uranium mines in the Grand Canyon region, the U.S. Geological Survey surveyed an approximately 200-meter-wide buffer surrounding four breccia-pipe deposits, each in a unique stage of mine development, and at one reference area (a livestock water tank) that underwent ground disturbance but contains no mineral deposits. We sectioned the buffer zones into 0.65–4.52 hectare plots, within which we (1) inventoried all plant species, (2) measured percent cover of plant species, plant functional groups, and ground surface types (dark cyanobacteria, lichen, moss, bedrock, rock, embedded litter, duff, plant bases, and bare soil) using line-point intercept, and (3) measured length and frequency of gaps between perennial plant canopies using canopy gap intercept. We found that plant composition at the mines and the reference area differed from one another but were all characteristic of expected regional vegetation patterns. We provide this data summary as potential baseline information for future research and management efforts.

Arizona↗
USGS2026

ECCOE Landsat Quarterly Calibration and Validation Report—Quarter 2, 2025

Executive Summary The U.S. Geological Survey Earth Resources Observation and Science Calibration and Validation (Cal/Val) Center of Excellence (ECCOE) focuses on improving the accuracy, precision, calibration, and product quality of remote-sensing data, leveraging years of multiscale optical system geometric and radiometric calibration and characterization experience. The ECCOE Landsat Cal/Val Team continually monitors the geometric and radiometric performance of active Landsat missions and makes calibration adjustments, as needed, to maintain data quality at the highest level. This report provides observed geometric and radiometric analysis results for Landsats 8 and 9 for quarter 2 (April–June) of 2025. All data used to compile the Cal/Val analysis results presented in this report are freely available from the U.S. Geological Survey EarthExplorer website: https://earthexplorer.usgs.gov .

Open-File Report↗
USGS2026

Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau

A detailed characterization of the >3,000 square kilometer (km 2 ) Springerville volcanic field, located on the southern tip of the Colorado Plateau in Arizona, United States, with its more than 501 volcanic units and widely distributed >420 cinder cones and lava flows, provides constraints toward an integrated petrogenetic model for the field. Large-volume effusive tholeiitic eruptions at 2–1.5 mega-annum (Ma) transitioned to more numerous, smaller volume alkali olivine basalt (AOB) events at 1.5–1.0 Ma, with increasing abundances of evolved alkalic rocks (EARs), and a final 1.0–0.3 Ma period dominated by smaller volume, more explosive alkalic eruptions. Early large-scale melting in a relatively enriched lithospheric mantle (EM) source generated large-volume effusive tholeiitic magmas. Depths of tholeiite magma generation average about 90 kilometers (km) across the field, but depths for individual units decreased southward, consistent with lithospheric thinning toward the Colorado Plateau margin. Early and middle-stage transitional basalts, alkali olivine basalts (AOBs), and basanites originate from a progressively deeper (>100 km) region in a prevalent mantle (PREMA)-like asthenospheric source produced by increasingly smaller degrees of melting, as low as about 2 percent. The chemical signature of the basanites is consistent with small degrees of melting in a carbonated, asthenospheric source to depths of about 140 km. As heat waned, the last phase of volcanism was dominated by more explosive EARs derived at shallower lithospheric pressures but that have isotopic and trace element similarities to the deeper asthenospheric magmas. This suggests mixing between deeper basanitic and shallower tholeiitic magmas. With waning heat, eruptions became more localized along alignments, likely related to boundaries between blocks of Proterozoic crust with differing properties that affected magma ascent. The petrogenetic patterns are consistent with a variety of processes. Basin and Range Province extension, melting, and heat-induced weakening progressively eroded the Colorado Plateau’s thicker lithosphere, giving rise to relatively high degrees of partial melting from shallower (<90 km) sources that produced the early large volumes of effusive tholeiitic magma. Possible lithosphere delamination and removal, and a resulting steep boundary step with the asthenosphere, may have given rise to mantle edge convection, resulting in the mixing of basanitic and tholeiitic magmas. With plate motion, shear-driven upwelling likely gave an eastward component to convection, affecting relative amounts of melting at the field’s western boundary and corresponding with volcanism moving eastward during times of peak vent production by eruption of alkalic lavas, giving rise to more explosive and lower volume eruptions.

Arizona, New Mexico↗
USGS2026

Multi-year cut-to-drown management limits Phragmites australis growth, belowground resources, and rhizome viability in Great Lakes wetlands

The distribution and abundance of Phragmites in the Great Lakes coastal zone has expanded in part due to its unique ventilation physiology and its ability to take advantage of changes in lake levels over the past several decades. During an extended period of low lake levels in the early 2000s, Phragmites expanded into vast shallow water areas as lake bottoms were exposed. Many of those populations were able to persist when lake levels rose several years later. Here, we investigate a management strategy, known as cut-to-drown, that takes advantage of elevated water levels to effectively control Phragmites by cutting stems underwater, thereby drowning the plant and depleting its stored resources. We tested the impacts of cut timing and frequency on the effectiveness of the cut-to-drown strategy through a multi-year manipulative field study. After two seasons of treatments, we found a 92–99 % reduction in stem density, depending on cut timing. Carbohydrate reserves in rhizomes declined 75–92 %, such that rhizome viability was reduced by 73–100 %, depending on cut timing. We found that cutting continuously (every 2–3 weeks) throughout two growing seasons was the most effective way to implement cut-to-drown but provide evidence that less frequent cutting could produce similar results. Our study provides important evidence to inform best management practices for cut-to-drown. Particularly as lake level fluctuations become more frequent and extreme in the future, cut-to-drown could serve as a useful tool for limiting Phragmites’ ability to persist in high water environments.

Michigan, Ohio↗
USGS2026

Single receiver target localization in mobile marine acoustic telemetry

Many marine ecological studies track animal movement and migration using acoustic telemetry, in which animals are implanted with acoustic transmitters broadcasting a unique ID code. Receivers detect and decode these transmissions and provide an estimate of the animal’s location. As transmissions can be detected at distances of hundreds of meters to even several kilometers, localization performed using binary detection information is very coarse. Fine-scale localization can be performed using time difference of arrival systems, but such systems are costlier and require a greater number of receivers. We present a Bayesian method for target localization using only binary detection information collected by a single receiver mounted on a mobile platform. The approach reduces error in the location estimate by considering the distance-dependent probability of detection (detection efficiency curve), which must first be characterized. Stationary receivers are used to infer failed detections. This localization method is then used to inform waypoint selection for the mobile platform, using the second nondominated sorting genetic algorithm considering the tradeoff between the travel distance of the platform and localization error. Simulation results examine the effects of detection efficiency curve characteristics, number of transmissions, and travel distance on the localization error. The proposed method is further supported by experimental results from field trials conducted with an autonomous surface vehicle in Lake Huron.

IEEE Journal of Oceanic Engineering↗
USGS2026

A matter of timing: Sagebrush steppe restoration seeding outcomes altered by species responses to warmer spring temperatures and interannual weather variation

Introduction Restoration outcomes in cold desert ecosystems like sagebrush steppe are affected by weather variability, particularly during the spring, a critical time period for seedling establishment. Seedling emergence phenology is also highly variable among species in these ecosystems. Seed-based restoration outcomes are likely affected by the emergence timing of species in seed mixes relative to periods of favorable soil microclimate in the spring. Objectives This study evaluated the effects of higher spring temperatures in different periods, and species differences in seedling emergence and survival, on restoration outcomes. We also tested the indirect effects of warming treatments on outcomes via abundance of cheatgrass, a competitive, widespread invasive annual sensitive to weather variability. Methods We used open-sided chambers to implement early- or late-spring warming on plots seeded with a diverse set of species that differed in timing of emergence, across multiple years and variable weather conditions in sagebrush steppe, Oregon, U.S.A. Results Spring warming treatment effects varied with yearly weather and species emergence timing relative to the rest of the seeded species. Later-emergence timing was associated with lower emergence rates, particularly with late spring warming, and lower survival with early spring warming, but higher survival without warming or with late spring warming. Seed mix scenarios tuned to warming treatment and yearly weather outperformed early- or late-emergence timing and even proportion mixes. Early spring warming increased invasive annual grass abundance, which was associated with lower survival of seeded species. Conclusions Species differences and yearly precipitation affected restoration outcomes under warmer spring temperatures.

Oregon↗
USGS2026

pySATSI: A Python package for computing focal mechanism stress inversions

We introduce pySATSI, a Python package for computing earthquake focal mechanism stress inversions. This algorithm can handle a wide variety of types of stress inversion problems with a single script and can duplicate many capabilities of preceding methodologies. We also add new capabilities that include spatiotemporally variable inversion grids, damped stress estimates for clusters with few or no focal mechanisms, and variable fault‐plane ambiguities that the user can assign to individual events. In addition, we added the ability to use damped stress inversions with fault‐plane ambiguity probabilities that are weighted by fault instabilities. Our algorithm is computationally efficient with faster runtimes than previous algorithms, scales well for large datasets, and can be easily parallelized.

Seismological Research Letters↗
USGS2026

Recent scientific contributions by the U.S. Geological Survey in the San Francisco Bay and Sacramento–San Joaquin Delta Estuary

Introduction The San Francisco Bay and Sacramento–San Joaquin Delta Estuary (hereafter, Bay-Delta) is the largest estuary on the West Coast of the United States. The Bay-Delta covers more than 1,600 square miles and drains a watershed of more than 75,000 square miles, which is greater than 40 percent of California. The region surrounding the Bay-Delta is home to about 10 million people, and its habitats (fig. 1) support more than 800 plant and animal species. The waterways of the Bay-Delta are the central hub of California’s extensive freshwater delivery system, supplying water to more than 27 million Californians and 4 million acres of farmland in the Central Valley. The U.S. Geological Survey (USGS) is the primary science agency of the U.S. Department of the Interior, providing a broad range of Earth, water, biological, and mapping data and expertise to inform natural resource management across the country. This fact sheet focuses on research conducted by the USGS in the Bay-Delta region, mostly within the past 5 years. The fact sheet is organized across five major themes: water flow and water quality, fish and wildlife, wetland restoration, invasive species, and hazards. In each of these areas, the USGS works closely with Federal, State, and local agencies; academia; and non-governmental organizations to provide objective, evidence-based science. The data and knowledge gained from USGS research and monitoring are publicly available and are routinely used by agencies, including the U.S. Bureau of Reclamation, U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, California Department of Water Resources, California Department of Fish and Wildlife, California State Water Resources Control Board, Delta Stewardship Council, and many additional organizations and stakeholders to inform management of the Bay-Delta region and its resources.

California↗