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At least 757 records · Page 42Linked to original sources

USGS2014

In-situ sediment oxygen demand rates in Hammonton Creek, Hammonton, New Jersey, and Crosswicks Creek, near New Egypt, New Jersey, August-October 2009

Sediment oxygen demand rates were measured in Hammonton Creek, Hammonton, New Jersey, and Crosswicks Creek, near New Egypt, New Jersey, during August through October 2009. These rates were measured as part of an ongoing water-quality monitoring program being conducted in cooperation with the New Jersey Department of Environmental Protection. Oxygen depletion rates were measured using in-situ test chambers and a non-consumptive optical electrode sensing technique for measuring dissolved oxygen concentrations. Sediment oxygen demand rates were calculated on the basis of these field measured oxygen depletion rates and the temperature of the stream water at each site. Hammonton Creek originates at an impoundment, then flows through pine forest and agricultural fields, and receives discharge from a sewage-treatment plant. The streambed is predominantly sand and fine gravel with isolated pockets of organic-rich detritus. Sediment oxygen demand rates were calculated at four sites on Hammonton Creek and were found to range from -0.3 to -5.1 grams per square meter per day (g/m 2 /d), adjusted to 20 degrees Celsius. When deployed in pairs, the chambers produced similar values, indicating that the method was working as expected and yielding reproducible results. At one site where the chamber was deployed for more than 12 hours, dissolved oxygen was consumed linearly over the entire test period. Crosswicks Creek originates in a marshy woodland area and then flows through woodlots and pastures. The streambed is predominantly silt and clay with some bedrock exposures. Oxygen depletion rates were measured at three sites within the main channel of the creek, and the calculated sediment oxygen demand rates ranged from -0.33 to -2.5 g/m 2 /d, adjusted to 20 degrees Celsius. At one of these sites sediment oxygen demand was measured in both a center channel flowing area of a pond in the stream and in a stagnant non-flowing area along the shore of the pond where organic-rich bottom sediments had accumulated and lower dissolved oxygen concentration conditions existed in the water column. Dissolved oxygen concentrations in the center channel test chamber showed a constant slow decrease over the entire test period. Oxygen consumption in the test chamber at the near-shore location began rapidly and then slowed over time as oxygen became depleted in the chamber. Depending on the portion of the near-shore dissolved oxygen depletion curve used, calculated sediment oxygen demand rates ranged from as low as -0.03 g/m 2 /d to as high as -10 g/m 2 /d. The wide range of sediment oxygen demand rates indicates that care must be taken when extrapolating sediment oxygen demand rates between stream sites that have different bottom sediment types and different flow regimes.

New Jersey↗

USGS2010

Assessment and monitoring of recreation impacts and resource conditions on mountain summits: Examples from the Northern Forest, USA

Mountain summits present a unique challenge to manage sustainably: they are ecologically important and, in many circumstances, under high demand for recreation and tourism activities. This article presents recent advances in the assessment of resource conditions and visitor disturbance in mountain summit environments, by drawing on examples from a multiyear, interdisciplinary study of summits in the northeastern United States. Primary impact issues as a consequence of visitor use, such as informal trail formation, vegetation disturbance, and soil loss, were addressed via the adaption of protocols from recreation ecology studies to summit environments. In addition, new methodologies were developed that provide measurement sensitivity to change previously unavailable through standard recreation monitoring protocols. Although currently limited in application to the northeastern US summit environments, the methods presented show promise for widespread application wherever summits are in demand for visitor activities.

Maine, Vermont, New Hampshire, New York, Massachus↗

USGS2009

Delayed conifer mortality after fuel reduction treatments: Interactive effects of fuel, fire intensity, and bark beetles

Many low‐elevation dry forests of the western United States contain more small trees and fewer large trees, more down woody debris, and less diverse and vigorous understory plant communities compared to conditions under historical fire regimes. These altered structural conditions may contribute to increased probability of unnaturally severe wildfires, susceptibility to uncharacteristic insect outbreaks, and drought‐related mortality. Broad‐scale fuel reduction and restoration treatments are proposed to promote stand development on trajectories toward more sustainable structures. Little research to date, however, has quantified the effects of these treatments on the ecosystem, especially delayed and latent tree mortality resulting directly or indirectly from treatments. In this paper, we explore complex hypotheses relating to the cascade of effects that influence ponderosa pine (Pinus ponderosa) and Douglas‐fir (Pseudotsuga menziesii) mortality using structural equation modeling (SEM). We used annual census and plot data through six growing seasons after thinning and four growing seasons after burning from a replicated, operational‐scale, completely randomized experiment conducted in northeastern Oregon, USA, as part of the national Fire and Fire Surrogate study. Treatments included thin, burn, thin followed by burn (thin + burn), and control. Burn and thin + burn treatments increased the proportion of dead trees while the proportion of dead trees declined or remained constant in thin and control units, although the density of dead trees was essentially unchanged with treatment. Most of the new mortality (96%) occurred within two years of treatment and was attributed to bark beetles. Bark beetle‐caused tree mortality, while low overall, was greatest in thin + burn treatments. SEM results indicate that the probability of mortality of large‐diameter ponderosa pine from bark beetles and wood borers was directly related to surface fire severity and bole charring, which in turn depended on fire intensity, which was greater in units where thinning increased large woody fuels. These results have implications when deciding among management options for restoring ecosystem health in similar ponderosa pine and Douglas‐fir forests.

Ecological Applications↗

USGS2024

Widespread occupancy of the endangered northern myotis on northeastern Atlantic Coastal Plain islands

Northern myotis Myotis septentrionalis are one of the bat species most affected by white-nose syndrome (WNS), and disease-induced declines may cause compounding effects when combined with other threats such as habitat loss and fragmentation. Recent evidence suggests that peripheral populations are persisting in post-WNS years; however, the environmental factors that influence the occurrence of this species along the Atlantic Coastal Plain are virtually unknown. We conducted a large-scale acoustic survey on 3 islands: Long Island, New York, and Martha’s Vineyard and Nantucket, Massachusetts, USA, and used a multi-scale occupancy modeling approach to determine the landscape and abiotic factors affecting the distribution of northern myotis. Our estimates of occupancy and detection probability suggest widespread presence across the islands. At the local (200 m) scale, we identified strong negative effects of development on Long Island and Nantucket and a strong positive effect of forest habitat on Martha’s Vineyard. None of the variables we measured sufficiently explained the landscape (1 km 2 ) occupancy of this species, which was very high (ψ = 0.81–0.97), representing an outlier for this species in the post-WNS landscape. The lack of association at the landscape scale suggests that general differences in land cover are not a driving factor of higher occupancy of peripheral northern myotis populations, while local site- specific conditions may be supporting critical foraging or roosting habitat. Because islands are particularly vulnerable to human-driven habitat alteration due to the constraint of limited space, and development pressure is expected to increase, this study provides a baseline to enable managers to assess the effects of future environmental disturbances and monitor population trends to support long-term survival of northern myotis.

Massachusetts, New York↗

USGS2023

Groundwater recharge in northern New England: Meteorological drivers and relations with low streamflow

Meteorological drivers of groundwater recharge for spring (February–June), fall (October–January), and recharge-year (October–June) recharge seasons were evaluated for northern New England and upstate New York from 1989 to 2018. Monthly groundwater recharge was computed at 21 observation wells by subtracting the water levels at the end of each month from the level of the previous month; only positive monthly values were used to compute seasonal recharge. Precipitation, temperature, sea-level pressure, 500-mb geopotential heights, and various teleconnection indices were tested as explanatory variables for the interannual variability of recharge using random forest machine learning models. Precipitation within recharge seasons was positively correlated with groundwater recharge for most wells in all seasons. In general, whilst groundwater recharge in the study area was generally highest during the months of March and April, October precipitation was an important month for explaining the interannual groundwater recharge variability. This is likely because the variability in recharge in October may be high or low for given years. Sea-level pressure and 500-mb heights were typically inversely correlated with groundwater recharge during the recharge-year and fall recharge seasons, as higher sea-level pressure and heights are usually associated with clearer skies and less precipitation. The North Atlantic Oscillation, Pacific-North American pattern, and Pacific Decadal Oscillation teleconnections affected groundwater recharge differently by well and season. The influence of groundwater recharge on minimum daily streamflows during the subsequent summer/fall was also analysed. Summer precipitation was the most important explanatory variable for study streams whilst groundwater recharge and summer air temperature were significant variables for a few streams.

Maine, New Hampshire, Vermont↗

USGS2006

Solute sources in stream water during consecutive fall storms in a northern hardwood forest watershed: A combined hydrological, chemical and isotopic approach

Understanding the effects of climate change including precipitation patterns has important implications for evaluating the biogeochemical responses of watersheds. We focused on four storms in late summer and early fall that occurred after an exceptionally dry period in 2002. We analyzed not only the influence of these storms on episodic chemistry and the role of different water sources in affecting surface water chemistry, but also the relative contributions of these storms to annual biogeochemical mass balances. The study site was a well studied 135-ha watershed in the Adirondack Park of New York State (USA). Our analyses integrated measurements on hydrology, solute chemistry and the isotopic composition of NO 3 − (δ 15 N and δ 18 O) and SO 4 2− (δ 34 S and δ 18 O) to evaluate how these storms affected surface water chemistry. Precipitation amounts varied among the storms (Storm 1: Sept. 14–18, 18.5 mm; Storm 2: Sept. 21–24, 33 mm; Storm 3: Sept. 27–29, 42.9 mm; Storm 4: Oct. 16–21, 67.6 mm). Among the four storms, there was an increase in water yields from 2 to 14%. These water yields were much less than in studies of storms in previous years at this same watershed when antecedent moisture conditions were higher. In the current study, early storms resulted in relatively small changes in water chemistry. With progressive storms the changes in water chemistry became more marked with particularly major changes in C b (sum of base cations), Si, NO 3 − , and SO 4 2− , DOC and pH. Analyses of the relationships between Si, DOC, discharge and water table height clearly indicated that there was a decrease in ground water contributions (i.e., lower Si concentrations and higher DOC concentrations) as the watershed wetness increased with storm succession. The marked changes in chemistry were also reflected in changes in the isotopic composition of SO 4 2− and NO 3 − . There was a strong inverse relationship between SO 4 2− concentrations and δ 34 S values suggesting the importance of S biogeochemical redox processes in contributing to SO 4 2− export. The isotopic composition of NO 3 − in stream water indicated that this N had been microbially processed. Linkages between SO 4 2− and DOC concentrations suggest that wetlands were major sources of these solutes to drainage waters while the chemical and isotopic response of NO 3 − suggested that upland sources were more important. Although these late summer and fall storms did not play a major role in the overall annual mass balances of solutes for this watershed, these events had distinctive chemistry including depressed pH and therefore have important consequences to watershed processes such as episodic acidification, and the linkage of these processes to climate change.

Biogeochemistry↗

USGS2009

NASA and USGS invest in invasive species modeling to evaluate habitat for Africanized Honey Bees

Invasive non-native species, such as plants, animals, and pathogens, have long been an interest to the U.S. Geological Survey (USGS) and NASA. Invasive species cause harm to our economy (around $120 B/year), the environment (e.g., replacing native biodiversity, forest pathogens negatively affecting carbon storage), and human health (e.g., plague, West Nile virus). Five years ago, the USGS and NASA formed a partnership to improve ecological forecasting capabilities for the early detection and containment of the highest priority invasive species. Scientists from NASA Goddard Space Flight Center (GSFC) and the Fort Collins Science Center developed a longterm strategy to integrate remote sensing capabilities, high-performance computing capabilities and new spatial modeling techniques to advance the science of ecological invasions [Schnase et al., 2002].

The Earth Observer↗

USGS2026

Identifying headwater streams across the conterminous United States

Headwater streams play critical roles in hydrologic and biogeochemical processes and functions, yet their spatial distribution and land cover context remain poorly understood at continental scales, and no dedicated geospatial dataset exists. Building from a high-resolution conterminous United States (CONUS) hydrography network dataset, we quantified the spatial extent, density, and upstream catchment characteristics of headwater stream segments across the CONUS. We identified approximately 8.4 million kilometers of headwater streams, finding that 77% of the total stream network consists of headwaters, nearly double the total length represented in prior estimates. Stream density varied fivefold across regions, from < 1 km·km −2 in arid basins to > 5 km·km −2 in humid, forested areas. Over 73% of the CONUS landmass drains from headwater streams. The majority of headwater stream length occurred in forested and cultivated catchments across the CONUS, while substantial regional differences were evident for headwater stream distribution in other land cover classes (for example, wetlands, urban areas, shrublands, and herbaceous-dominated catchments). The dedicated and novel geospatial dataset, HELiOS (HEadwater streams and Low-Order Systems) is introduced for management and research use. The HELiOS dataset provides the first continental-scale, high-resolution characterization of headwater streams, offering new insights and opportunities for hydrologic modeling, ecological assessments, and environmental policy.

conterminous United States↗

USGS2012

High-resolution digital elevation dataset for Crater Lake National Park and vicinity, Oregon, based on LiDAR survey of August-September 2010 and bathymetric survey of July 2000

Crater Lake partially fills the caldera that formed approximately 7,700 years ago during the eruption of a 12,000-foot volcano known as Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama devastated the surrounding landscape, left a thick deposit of pumice and ash in adjacent valleys, and spread a blanket of volcanic ash as far away as southern Canada. Because the Crater Lake region is potentially volcanically active, knowledge of past events is important to understanding hazards from future eruptions. Similarly, because the area is seismically active, documenting and evaluating geologic faults is critical to assessing hazards from earthquakes. As part of the American Recovery and Reinvestment Act (ARRA) of 2009, the U.S. Geological Survey was awarded funding for high-precision airborne LiDAR ( Li ght D etection A nd R anging) data collection at several volcanoes in the Cascade Range through the Oregon LiDAR Consortium, administered by the Oregon Department of Geology and Mineral Industries (DOGAMI). The Oregon LiDAR Consortium contracted with Watershed Sciences, Inc., to conduct the data collection surveys. Collaborating agencies participating with the Oregon LiDAR Consortium for data collection in the Crater Lake region include Crater Lake National Park (National Park Service) and the Federal Highway Administration. In the immediate vicinity of Crater Lake National Park, 798 square kilometers of LiDAR data were collected, providing a digital elevation dataset of the ground surface beneath forest cover with an average resolution of 1.6 laser returns/m 2 and both vertical and horizontal accuracies of ±5 cm. The LiDAR data were mosaicked in this report with bathymetry of the lake floor of Crater Lake, collected in 2000 using high-resolution multibeam sonar in a collaborative effort between the U.S. Geological Survey, Crater Lake National Park, and the Center for Coastal and Ocean Mapping at the University of New Hampshire. The bathymetric survey collected 16 million soundings with a spatial resolution of 2 meters using an EM1002 system owned and operated by C&C Technologies, Inc. The combined LiDAR and bathymetric dataset has a cell size of 1 meter and will contribute to understanding past volcanic events and their deposits, recognizing of faults and volcanic landforms, and quantifying landscape modification during and after the next volcanic eruption at Crater Lake.

Oregon↗

USGS2020

2023 Coastal master plan: Model improvement plan, ICM-wetlands, vegetation, and soil

As part of the model improvement effort for the 2023 Coastal Master Plan, the wetland processes captured by the morphology and vegetation models used during previous master plans were reevaluated to assess how Integrated Compartment Model (ICM) subroutines could be improved. This process considered technical reviews, comments, and suggested improvements provided by model developers, advisory groups, and other experts during previous master plan cycles. The availability of new data and information that could be used to make model improvements was also considered. In many cases, the team considered and tested multiple options or approaches. As a result of this effort, recommended improvements are provided here. The improvements recommended to be included in the 2023 Coastal Master Plan include: adjusting marsh collapse thresholds, refining organic matter accretion calculations, developing an unstructured grid for modeling vegetation, improving flotant marsh and forested wetlands algorithms, creating and applying an updated map of existing vegetation, adjusting model code, and updating the submerged aquatic vegetation (SAV) module. This report describes the team’s work through a series of 7 distinct activities to identify and test options for model improvements to ensure the updated ICM used for the 2023 Coastal Master Plan appropriately captures ecological and morphological processes observed in Coastal Louisiana. As appropriate, relevant literature and data are discussed. Test runs to evaluate how changes influence model outputs are also documented. A final list of recommended updates, taking into account consideration of all options and results from test runs, is summarized at the end of the report. A later report will describe the final ICM-LAVegMod and ICM-Morph subroutines for the 2023 Coastal Master Plan, detailing the updates that have been incorporated.

Louisiana↗

USGS2024

Patterns and drivers of cottonwood mortality in the middle Rio Grande, New Mexico, USA

Riparian ecosystems are some of the most valuable and vulnerable on the planet. Riparian tree mortality is increasing in the western United States, where altered streamflows are combining with warming climate. Between 2011 and 2013, one third of an extensive stand of Populus deltoides var. wislizeni (Rio Grande cottonwood) died along the middle Rio Grande on the Pueblo of Santa Ana in New Mexico. Mortality coincided with a severe drought that followed a decade of decreasing streamflow, but it was heterogeneous, with adjacent patches of dead and live trees. The goal of this research was to determine the drivers of mortality to provide insights into future risks of die-off and potential management interventions. We compared tree age, competition, tree-ring widths, sediment particle size and climate influences between live and dead forest patches in a nested plot design. Live and dead trees had similar age, stand density and particle sizes of shallow sediments. Tree-ring widths had the highest correlations with July–September streamflow (1932–2013). All trees had declining ring growth since 1992, coinciding with declining late summer streamflow. An accelerated decline in growth began in 2002, corresponding to recent warmer droughts. Trees that died had lower ring growth 3 years prior to death and in the mid-1900s. Dead trees also had coarser deep sediments 2.4–3.7 m below ground, suggesting that reduced water holding capacity was an important factor for mortality. Water management to increase streamflow during the late summer, especially during times of extended drought, could reduce mortality risk in the face of projected increasingly warm droughts.

New Mexico↗

USGS1990

Fire - Southern Oscillation relations in the southwestern United States

Fire scar and tree growth chronologies (1700 to 1905) and fire statistics (since 1905) from Arizona and New Mexico show that small areas burn after wet springs associated with the low phase of the Southern Oscillation (SO), whereas large areas burn after dry springs associated with the high phase of the SO. Through its synergistic influence on spring weather and fuel conditions, climatic variability in the tropical Pacific significantly influences vegetation dynamics in the southwestern United States. Synchrony of fire-free and severe fire years across diverse southwestern forests implies that climate forces fire regimes on a subcontinental scale; it also underscores the importance of exogenous factors in ecosystem dynamics.

Arizona, New Mexico↗

USGS2022

Rhode Island and Landsat

Rhode Island is an oasis of natural calm surrounded by heavily urbanized East Coast areas, which may explain why the smallest State in the United States is such a popular tourist destination for residents of New York, Pennsylvania, and New Jersey, or perhaps its popularity is a measure of the Ocean State’s abundant wildlife and picturesque views. Although small in land area, Rhode Island claims the largest estuary in New England in the 147-square-mile Narragansett Bay. Locals and visitors feast on clams caught in the bay, trek to glimpse shorebirds, or boat to 1 of 30 islands. As with any coastal State, the natural wonders of Rhode Island are affected by changes in sea levels and ocean temperatures. State agencies also work to fend off foes like the invasive Lymantria dispar (Linnaeus, 1758; spongy moth) and protect the forests that cover more than one-half of Rhode Island. The U.S. Geological Survey Landsat Program, with 54 plus years of recurring Earth observations from space, offers a unique and freely available public data source for the study of land and coastal change across Rhode Island and the United States. Here are just a few of the ways Landsat imagery has been used to benefit the State.

Rhode Island↗

USGS2002

Geologic map of the Tetilla Peak Quadrangle, Santa Fe and Sandoval counties, New Mexico

This digital geologic map summarizes all available geologic information for the Tetilla Peak quadrangle located immediately southwest of Santa Fe, New Mexico. The geologic map consists of new polygon (geologic map units) and line (contact, fault, fold axis, dike, flow contact, hachure) data, as well as point data (locations for structural measurements, geochemical and geochronologic data, geophysical soundings, and water wells). The map database has been generated at 1:24,000 scale, and provides significant new geologic information for an area of the southern Cerros del Rio volcanic field, which sits astride the boundary of the Espanola and Santo Domingo basins of the Rio Grande rift. The quadrangle includes the west part of the village of La Cienega along its eastern border and includes the southeasternmost part of the Cochiti Pueblo reservation along its northwest side. The central part of the quadrangle consists of Santa Fe National Forest and Bureau of Land Management lands, and parts of several Spanish-era land grants. Interstate 25 cuts through the southern half of the quadrangle between Santa Fe and Santo Domingo Pueblo. Canada de Santa Fe, a major river tributary to the Rio Grande, cuts through the quadrangle, but there is no dirt or paved road along the canyon bottom. A small abandoned uranium mine (the La Bajada mine) is found in the bottom of the Canada de Santa Fe about 3 km east of the La Bajada fault zone; it has been partially reclaimed. The surface geology of the Tetilla Peak quadrangle consists predominantly of a thin (1-2 m generally, locally as thick as 10? m) layer of windblown surficial deposits that has been reworked colluvially. Locally, landslide, fluvial, and pediment deposits are also important. These colluvial deposits mantle the principal bedrocks units, which are (from most to least common): (1) basalts, basanites, andesite, and trachyte of the Pliocene (2.7-2.2 Ma) Cerros del Rio volcanic field; (2) unconsolidated deposits of the Santa Fe Group, mainly along the western border, in the hanging wall of the La Bajada fault zone, but locally extending 2-3 km east under the Cerros del Rio volcanic field; (3) older Tertiary volcanic and sedimentary rocks (Abiquiu?, Espinaso, and Galisteo Formations); (4) intrusive rocks of the Cerrillos intrusive center that are roughly coeval with the Espinaso volcanic rocks; and (5) Mesozoic sedimentary rocks ranging in age from the Upper Triassic Chinle Formation to the Upper Cretaceous Mancos Shale.

New Mexico↗

USGS2025

Physical habitat is more than a sediment issue: A multi-dimensional habitat assessment indicates new approaches for river management

Degraded physical habitat is a common stressor affecting river ecosystems and typically addressed in the United States (US) through a regulatory focus on sediment. However, a narrow regulatory focus on sediment may overlook other aspects of physical habitat and the processes for its creation, maintenance, and degradation. In addition, there exist few “ready-to-use” regional assessments of the multiple dimensions of physical habitat to better understand continuous patterns of condition and prioritize management efforts across a large spatial scale. In this study, we use rapid habitat monitoring data to train a machine-learning ( i.e., random forest) model to predict twelve physical habitat metrics for nearly 120,000 km of nontidal rivers and streams across the Chesapeake Bay watershed, US. We capture a range of habitat conditions driven by both natural variables and anthropogenic pressures. Covariation among habitat metrics indicated two major dimensions of habitat variation: 1) coarse bed substrate and hydromorphic heterogeneity and 2) bank stability and riparian condition. The model predicted localized changes from 2001 to 2019, and the predicted areas of deterioration roughly balanced improvements across the watershed, indicating little progress towards long-term watershed management goals. To evaluate connections to regulatory and management endpoints, we compared our physical habitat predictions to paired estimates of sediment and flow alteration across the region. Sediment concentrations were greater in reaches with less bank stability and lower riparian quality; however, the relation was weak for coarse bed condition metrics, including embeddedness, which is frequently used for establishing regulatory sediment restrictions. For flow alteration, most habitat metrics had lower scores with altered flow metrics, but metrics of instream habitat heterogeneity and coarse substrate condition were most strongly affected. Increased flashy, high flows negatively affected most metrics, but coarse substrate metrics were also negatively affected by greater low flow severity. This study highlights a potential disconnect between a narrow focus on regulatory sediment targets given the multiple dimensions and responses of physical habitat. A more holistic approach to physical habitat in management interventions – one that considers hydromorphic processes, diversity and variability in microhabitats, and explicit consideration of alterations to both low and high flows – may be warranted. By providing direct estimates of multiple aspects of physical habitat, this model can help support managers in the Chesapeake Bay watershed to better understand the range of habitat conditions, identify high-quality reaches for conservation, and target potential management actions tailored to localized conditions.

Delaware, Maryland, New York, Pennsylvania, Virgin↗

USGS1974

Mineral resources of proposed additions to the Salmon-Trinity Alps Primitive Area, California

A mineral survey of four areas totalling 80 square miles, not included during the 1968-70 examination of the proposed Salmon-Trinity Alps Wilderness, was made by the U.S. Geological Survey and U.S. Bureau of Mines in 1973. Geological Survey personnel mapped the geology and collected stream-sediment and rock samples for spectrographic and chemical analysis; Bureau of Mines personnel examined the known placer and lode claims. The areas examined include: (1) the upper drainage of Red Cap Creek in Humboldt County, adjoining the northwest part of the Salmon-Trinity Alps Primitive Area; (2) an area in Trinity County south of the Primitive Area including the drainage of Big French Creek and the canyon of North Fork Trinity River from Hobo Gulch Forest Camp to the junction with East Fork of North Fork; (3) an area, also south of the Primitive Area and in Trinity County, including East Fork of North Fork from Manzanita Flat to Squaw Gulch, and the drainages of Indian Creek, Squaw Gulch, lower East Branch, and lower Yellow Jacket Creek; (4) the drainage of St. Clair Creek in Siskiyou County north of the Primitive Area; and (5) a small area on New River from the junction of Slide and Virgin Creeks downstream to the mouth of Barron Creek that was previously mapped by the Geological Survey (Hotz and others, 1972) but had not been studied by the Bureau of Mines.

California↗

USGS2020

Vegetation responses to Quaternary volcanic and hydrothermal disturbances in the Northern Rocky Mountains and Greater Yellowstone Ecosystem (USA)

Volcanic and hydrothermal processes produce disturbances by diverse mechanisms and ecological responses are varied. New and published pollen records from the Northern Rocky Mountains and Greater Yellowstone Ecosystem document the response of vegetation to three different types of volcanic and hydrothermal disturbances: (1) Pleistocene rhyolite lava flows in the central Greater Yellowstone Ecosystem created infertile landscapes that have shaped vegetation since rhyolite emplacement. Nutrient-poor, well-drained soils that developed on these flows supported low-diversity grassland during late-glacial time and Pinus contorta forests in interglacial periods. (2) Ash layers from eruptions of Pacific Northwest stratovolcanoes are commonly preserved in lake-sediment records in the Northern Rocky Mountains, and associated pollen records show enhancement of steppe vegetation for years to decades. (3) Local hydrothermal explosions have resulted in vegetation changes in hydrothermal areas that indicate tree mortality following deposition of explosion debris, followed by recovery in years. Thus, the type and duration of the vegetation response to volcanic and hydrothermal disturbances are highly contextual and governed by the antecedent plant communities and the magnitude and mechanism of the volcanic or hydrothermal disturbance. Vegetation resilience varied between disturbances, ranging from enduring ecosystem parameter changes to short-lived state changes in resilient plant communities.

Idaho, Montana, Wyoming↗

USGS1996

Water-quality assessment of the Connecticut, Housatonic, and Thames River Basins study unit: Analysis of available data on nutrients, suspended sediments, and pesticides, 1972-92

This retrospective report examines available nutrient, suspended sediment, and pesticide data in surface and ground water in the Connecticut, Housatonic and Thames Rivers Study Unit of the National Water-Quality Assessment Program. The purpose of this study is to improve the understanding of natural and anthropogenic factors affecting water quality in the study unit. Waterquality data were acquired from various sources, primarily, the U.S. Geological Survey and the U.S. Environmental Protection Agency. The report examines data for water years 1972-92, focusing on 1980-92, although it also includes additional data from as early as 1905. The study unit lies within the New England Physiographic Province and altitudes range from sea level in coastal Connecticut to 6,288 feet above sea level at Mount Washington, New Hampshire. Two major aquifer types underlie the study unit unconsolidated glacial deposits and fractured bedrock. The climate generally is temperate and humid, with four distinct seasons. Average annual precipitation ranges from 34 to 65 inches. The study unit has a population of about 4.5 million, which is most highly concentrated in southwestern Connecticut and along the south-central region of the Connecticut River Valley. Surface-water-quality data were screened to provide information about sites with adequate numbers of analyses (50) over sufficiently long periods (1980-90) to enable valid statistical analyses. In order to compare effects of different types of land use on surface-water quality, examination of data required application of several statistical and graphical techniques, including mapping, histograms, boxplots, concentration-discharge plots, trend analysis, and load estimation. Spatial and temporal analysis of surface-water-quality data indicated that, with a single exception, only stations in the Connecticut water-quality network had sufficient data collected over adequately long time periods to use in detailed analyses. Ground-water nutrient and pesticide data were compiled from several Federal and State agencies, primarily the U.S. Geological Survey, U.S. Environmental Protection Agency, and Connecticut Department of Health Services. Nutrient data were available for several thousand wells; nitrite plus nitrate as nitrogen was the most commonly reported constituent. Most wells with nutrient data are in Massachusetts and Connecticut. Relative to nutrient data in ground and surface water, pesticide data are less common. Pesticide data were available for slightly more than 200 surface-water sites and less than 500 wells; about 95 percent of the wells are completed in stratified-drift or till aquifers. Data for 81 pesticide compounds were available in various data bases. 2,4-D and silvex were the most commonly detected herbicides in surface water and dieldrin and diazinon were the most commonly detected insecticides. Most surface-water pesticide samples and detections are from bed sediment, but much of the data are not recent. Ethylene dibromide (EDB), a soil fumigant used in tobacco farming was detected in 268 wells in a 50 square-mile area of north-central Connecticut; EDB contamination also was detected in wells in Massachusetts. Atrazine, an herbicide commonly used in corn farming, commonly was detected in wells installed in tilled agricultural fields. Corn herbicides were commonly detected in the northern part of the study unit, although the sampling has been less frequent than in the southern part of the study unit. Pesticides were seldom detected in public-supply wells in Connecticut. Urban sites with relatively high population densities and high concentrations of dischargers were characterized by having the highest nutrient concentrations and loads when adjusted for differences in drainage area or population. Particularly, the Pequabuck, Naugatuck, and Quinnipiac River Basins were characterized by high nutrient concentrations median total nitrogen concentrations ranged from 3.3 to 4.2 mg/L (milligrams per liter) and median total phosphorus concentrations ranged from 0.42 to 0.8 mg/L. In contrast, the predominantly forested and low density residential land-use sites, such as Saugatuck and Salmon River Basins, were characterized by low nutrient concentrations median total nitrogen ranged from 0.50 to 0.60 mg/L and median total phosphorus concentrations ranged from 0.01 to 0.02 mg/L. Estimated total nitrogen loadings in median discharge years ranged from 940 kilograms per square mile at the Salmon River near East Hampton, Conn., to 5,800 kilograms per square mile at the Naugatuck River at Beacon Falls, Conn. Water quality, in terms of nutrient concentrations and areally adjusted loadings, for sites with large drainage basins integrating a wide variety of land-use categories fell between the extremes of the urban and forested sites total nitrogen was 1,400 kilograms per square mile per year at the Connecticut River at Thompsonville, Conn. Nitrate concentrations in ground water occasionally exceeded the safe drinking-water standard of 10 mg/L as nitrogen. The greatest number of detections exceeding the standard, however, were not in public-water supplies but in shallow observation wells in agricultural settings (the most frequently sampled type of well). None of the public-supply wells in Massachusetts exceeded the standard. Although nitrate concentrations for Vermont and New Hampshire generally were low, few data were available and those were seldom reported on the basis of drainage basin, making analysis difficult. Trend analysis indicated that flow-adjusted concentrations of total and dissolved phosphorus generally decreased during the period of analysis, however, total nitrogen did not change substantially. Decreases in ammonia concentrations with time were usually accompanied by increases in nitrate, suggesting improvements in sewage treatment. The lack of adequate data from more or less exclusively agricultural areas points to the need for further study of the effects of fanning on surface-water quality in the study unit. Furthermore, additional information is needed on the rates, transformations, and movements of nutrients and other materials through and between the aquatic and terrestrial components of the study unit.

Connecticut, Massachusetts, New Hampshire, Quebec,↗