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At least 1,063 records · Page 59Linked to original sources
USGS2012

Effects of urban best management practices on streamflow and phosphorus and suspended-sediment transport on Englesby Brook in Burlington, Vermont, 2000-2010

An assessment of the effectiveness of several urban best management practice structures, including a wet extended detention facility and a shallow marsh wetland (together the "wet extended detention ponds"), was made using data collected from 2000 through 2010 at Englesby Brook in Burlington, Vermont. The purpose of the best management practices was to reduce high streamflows and phosphorus and suspended-sediment loads and concentrations and to increase low streamflows. Englesby Brook was monitored for streamflow, phosphorus, and suspended-sediment concentrations at a streamgage downstream of the best management practice structures for 5 years before the wet extended detention ponds were constructed in 2005 and for 4 years (phosphorus and suspended-sediment concentrations) or 5 years (streamflow) after they were constructed. The period after construction of the best management practice structures was wetter and had higher discharges than the period before construction. Despite the wetter conditions, streamflow duration curves provided evidence that the streamflow regime appeared to have shifted so that the percentages of low streamflows have increased and those of high streamflows may have slightly decreased. Two other hydrologic measures showed improvements in the years following construction of the best management practices: the percentage of annual discharge transported during the 3 days with highest discharges and the number of days with zero streamflow have both decreased. Evidence was mixed for the effectiveness of the best management practices in reducing phosphorus and suspended-sediment concentrations and loads. Annual phosphorus and suspended-sediment loads, monthly loads, low-streamflow concentrations, storm-averaged streamflow-adjusted concentrations, and total storm loads either did not change significantly or increased in the period after construction. These results likely were because of the wetter conditions in the period after construction. For example, monthly loads assessed using analysis of covariance, which compensated for the effects of streamflow on loads, suggested no difference in phosphorus or suspended-sediment loads between the two periods, whereas the comparison of monthly loads without factoring in streamflow showed an increase. This result could be viewed as evidence that the ponds may have mitigated the effect of greater discharges in the period after construction by preventing a corresponding increase in loads. In another analysis used to adjust for the difference in discharge between the two comparison periods, annual and monthly load results were grouped into dry and wet years. Large (50 percent) reductions in annual loads were observed when data from dry (or wet) years before construction were compared with data from dry (or wet) years after construction. When paired monthly loads of each constituent were grouped into dry and wet years, approximately the same number of months had increases as did decreases with the magnitudes of the decreases generally larger than the magnitudes of the increases. These differences in magnitude explain the decrease in annual loads for dry and wet years. The close association of phosphorus with suspended-sediment data suggested that most of the phosphorus was in the particulate form and was controlled by suspended-sediment dynamics.

Vermont↗
USGS2016

Design and testing of a process-based groundwater vulnerability assessment (P-GWAVA) system for predicting concentrations of agrichemicals in groundwater across the United States

Efforts to assess the likelihood of groundwater contamination from surface-derived compounds have spanned more than three decades. Relatively few of these assessments, however, have involved the use of process-based simulations of contaminant transport and fate in the subsurface, or compared the predictions from such models with measured data—especially over regional to national scales. To address this need, a process-based groundwater vulnerability assessment (P-GWAVA) system was constructed to use transport-and-fate simulations to predict the concentration of any surface-derived compound at a specified depth in the vadose zone anywhere in the conterminous United States. The system was then used to simulate the concentrations of selected agrichemicals in the vadose zone beneath agricultural areas in multiple locations across the conterminous United States. The simulated concentrations were compared with measured concentrations of the compounds detected in shallow groundwater (that is, groundwater drawn from within a depth of 6.3 ± 0.5 meters [mean ± 95 percent confidence interval] below the water table) in more than 1,400 locations across the United States. The results from these comparisons were used to select the simulation approaches that led to the closest agreement between the simulated and the measured concentrations. The P-GWAVA system uses computer simulations that account for a broader range of the hydrologic, physical, biological and chemical phenomena known to control the transport and fate of solutes in the subsurface than has been accounted for by any other vulnerability assessment over regional to national scales. Such phenomena include preferential transport and the influences of temperature, soil properties, and depth on the partitioning, transport, and transformation of pesticides in the subsurface. Published methods and detailed soil property data are used to estimate a wide range of model input parameters for each site, including surface albedo, surface crust permeability, soil water content, Brooks-Corey parameters, saturated hydraulic conductivity, macroporosity and sizes of microbial populations, as well as solute partition coefficients, reaction rates, and meso-micropore diffusion rates. To ensure geographic consistency among the predictions, the only site-specific input data that are used are those that are available for all of the 48 conterminous states.

Scientific Investigations Report↗
USGS2015

Continuous monitoring of sediment and nutrients in the Illinois River at Florence, Illinois, 2012-13

The Illinois River is the largest river in Illinois and is the primary contributing watershed for nitrogen, phosphorus, and suspended-sediment loading to the upper Mississippi River from Illinois. In addition to streamflow, the following water-quality constituents were monitored at the Illinois River at Florence, Illinois (U.S. Geological Survey station number 05586300), during May 2012–October 2013: phosphate, nitrate, turbidity, temperature, specific conductance, pH, and dissolved oxygen. The objectives of this monitoring were to (1) determine performance capabilities of the in-situ instruments; (2) collect continuous data that would provide an improved understanding of constituent characteristics during normal, low-, and high-flow periods and during different climatic and land-use seasons; (3) evaluate the ability to use continuous turbidity as a surrogate constituent to determine suspended-sediment concentrations; and (4) evaluate the ability to develop a regression model for total phosphorus using phosphate, turbidity, and other measured parameters. Reliable data collection was achieved, following some initial periods of instrument and data-communication difficulties. The resulting regression models for suspended sediment had coefficient of determination (R 2 ) values of about 0.9. Nitrate plus nitrite loads computed using continuous data were found to be approximately 8 percent larger than loads computed using traditional discrete-sampling based models. A regression model for total phosphorus was developed by using historic orthophosphate data (important during periods of low flow and low concentrations) and historic suspended-sediment data (important during periods of high flow and higher concentrations). The R 2 of the total phosphorus regression model using orthophosphorus and suspended sediment was 0.8. Data collection and refinement of the regression models is ongoing.

Illinois↗
USGS2016

Historical water-quality data from the Harlem River, New York

Data specific to the Harlem River, New York, have been summarized and are presented in this report. The data illustrate improvements in the quality of water for the past 65 years and emphasize the importance of a continuous water-quality record for establishing trends in environmental conditions. Although there is a paucity of sediment-quality data, the New York City Department of Environmental Protection (NYCDEP) Bureau of Wastewater Treatment has maintained a water-quality monitoring network in the Harlem River (and throughout the harbor of New York City) to which 61 combined sewer outfalls discharge effluent. In cooperation with the NYCDEP, the U.S. Geological Survey evaluated water-quality data collected by the NYCDEP dating back to 1945, which indicate trends in water quality and reveal improvement following the 1972 passage of the Clean Water Act. These improvements are indicated by the steady increase in median dissolved oxygen concentrations and an overall decrease in fecal indicator bacteria concentrations starting in the late 1970s. Further, the magnitude of the highest fecal indicator bacteria concentrations (that is, the 90th percentile) in samples collected from the Harlem River have decreased significantly over the past four decades. Other parameters of water quality used to gauge the health of a water body include total suspended solids and nutrient (inorganic forms of nitrogen and phosphorus) concentrations—mean concentrations for these indicators have also decreased in the past decades. The limited sediment data available for one sample in the Harlem River indicate concentrations of copper, zinc, and lead are above sediment-quality thresholds set by the New York State Department of Environmental Conservation. However, more data are needed to better understand the changes in both sediment and water quality in the Harlem River, both as the tide cycles and during precipitation events. As a partner in the Urban Waters Federal Partnership, the U.S. Geological Survey has worked to address the chronic water-quality concerns of the Harlem River by compiling relevant data and studies, which is an important component for understanding and rectifying water-quality problems within a watershed.

New York↗
USGS2016

Performance evaluation testing of wells in the gradient control system at a federally operated Confined Disposal Facility using single well aquifer tests, East Chicago, Indiana

The U.S. Geological Survey (USGS) performed tests to evaluate the hydrologic connection between the open interval of the well and the surrounding Calumet aquifer in response to fouling of extraction well pumps onsite. Two rounds of air slug testing were performed on seven monitoring wells and step drawdown and subsequent recovery tests on three extraction wells on a U.S. Army Corps of Engineers Confined Disposal Facility (CDF) in East Chicago, Indiana. The wells were tested in 2014 and again in 2015. The extraction and monitoring wells are part of the gradient control system that establishes an inward gradient around the perimeter of the facility. The testing established a set of protocols that site personnel can use to evaluate onsite well integrity and develop a maintenance procedure to evaluate future well performance. The results of the slug test analysis data indicate that the hydraulic connection of the well screen to the surrounding aquifer material in monitoring wells on the CDF and the reliability of hydraulic conductivity estimates of the surrounding geologic media could be increased by implementing well development maintenance. Repeated air slug tests showed increasing hydraulic conductivity until, in the case of the monitoring wells located outside of the groundwater cutoff wall (MW–4B, MW–11B, MW–14B), the difference in hydraulic conductivity from test to test decreased, indicating the results were approaching the optimal hydraulic connection between the aquifer and the well screen. Hydraulic conductivity values derived from successive tests in monitoring well D40, approximately 0.25 mile south of the CDF, were substantially higher than those derived from wells on the CDF property. Also, values did not vary from test to test like those measured in monitoring wells located on the CDF property, which indicated that a process may be affecting the connectivity of the wells on the CDF property to the Calumet aquifer. Derived hydraulic conductivity values from the initial air slug test during the 2015 testing period for MW–11A and MW–14A are an order of magnitude less than those derived from the final test during the 2014 testing period indicating the development of a low conductivity skin between the final test of the 2014 testing period and the beginning of the 2015 testing period that created a decrease in the connection of the monitoring well screen to the surrounding aquifer material. Repeated step drawdown and recovery testing of the extraction wells tested during this study provided results that indicate a slight increase in the development of a skin and a decrease in the connectivity of the extraction wells with the Calumet aquifer. Hydraulic conductivity values obtained from the test results were relatively similar in EW–4B and EW–14A but were substantially lower for EW–11C. This difference may be due to the presence of finer grained silt deposits in the area surrounding well nest 11. Skin factors calculated during the step drawdown and recovery analysis were lowest in EW–11C and relatively similar in EW–4B and EW–14A. Calculated skin factors increased slightly in the analysis of data collected in 2015 from that collected in 2014. Comparisons of the specific-capacity values calculated from well development data collected following extraction well installation to those calculated during the single well aquifer tests at EW–4B, EW–14A and EW–11C indicate that the productivity of extraction wells on the CDF property has diminished since 2008. Values calculated for monitoring wells MW–4A, MW–11A, and MW–14A were used to evaluate the decrease in air slug derived hydraulic conductivity for monitoring wells within the groundwater cutoff wall between testing in 2014 and 2015. Results from testing by this study indicate that implementation of an air slug testing regimen of the monitoring wells that control the gradient control system at the CDF throughout the course of a year may help sustain the connectivity between the monitoring wells and the surrounding aquifer and provide data to evaluate the need for different types of well development approaches to address chemical or biological fouling issues. Repeated step drawdown and recovery testing of the extraction wells tested during this study provided results that indicate a slight increase in the development of a skin and a decrease in the connectivity of the extraction wells with the Calumet aquifer. Implementation of a specific capacity testing regimen can provide data to record and track well condition through time for individual extraction wells. Results from aquifer testing by this study indicate that specific capacity test results, when paired with recovery testing, provide useful data to measure the development of any low conductivity wellbore skin through the skin factors derived for the individual extraction wells. An initial annual schedule of specific capacity and recovery tests would provide sufficient data to identify substantial short-term changes in the operating condition of the extraction wells.

Indiana↗
USGS2017

Simulated groundwater flow paths, travel time, and advective transport of nitrogen in the Kirkwood-Cohansey aquifer system, Barnegat Bay–Little Egg Harbor Watershed, New Jersey

Elevated concentrations of nitrogen in groundwater that discharges to surface-water bodies can degrade surface-water quality and habitats in the New Jersey Coastal Plain. An analysis of groundwater flow in the Kirkwood-Cohansey aquifer system and deeper confined aquifers that underlie the Barnegat Bay–Little Egg Harbor (BB-LEH) watershed and estuary was conducted by using groundwater-flow simulation, in conjunction with a particle-tracking routine, to provide estimates of groundwater flow paths and travel times to streams and the BB-LEH estuary. Water-quality data from the Ambient Groundwater Quality Monitoring Network, a long-term monitoring network of wells distributed throughout New Jersey, were used to estimate the initial nitrogen concentration in recharge for five different land-use classes—agricultural cropland or pasture, agricultural orchard or vineyard, urban non-residential, urban residential, and undeveloped. Land use at the point of recharge within the watershed was determined using a geographic information system (GIS). Flow path starting locations were plotted on land-use maps for 1930, 1973, 1986, 1997, and 2002. Information on the land use at the time and location of recharge, time of travel to the discharge location, and the point of discharge were determined for each simulated flow path. Particle-tracking analysis provided the link from the point of recharge, along the particle flow path, to the point of discharge, and the particle travel time. The travel time of each simulated particle established the recharge year. Land use during the year of recharge was used to define the nitrogen concentration associated with each flow path. The recharge-weighted average nitrogen concentration for all flow paths that discharge to the Toms River upstream from streamflow-gaging station 01408500 or to the BB-LEH estuary was calculated. Groundwater input into the Barnegat Bay–Little Egg Harbor estuary from two main sources— indirect discharge from base flow to streams that eventually flow into the bay and groundwater discharge directly into the estuary and adjoining coastal wetlands— is summarized by quantity, travel time, and estimated nitrogen concentration. Simulated average groundwater discharge to streams in the watershed that flow into the BB-LEH estuary is approximately 400 million gallons per day. Particle-tracking results indicate that the travel time of 56 percent of this discharge is less than 7 years. Fourteen percent of the groundwater discharge to the streams in the BB-LEH watershed has a travel time of less than 7 years and originates in urban land. Analysis of flow-path simulations indicate that approximately 13 percent of the total groundwater flow through the study area discharges directly to the estuary and adjoining coastal wetlands (approximately 64 million gallons per day). The travel time of 19 percent of this discharge is less than 7 years. Ten percent of this discharge (1 percent of the total groundwater flow through the study area) originates in urban areas and has a travel time of less than 7 years. Groundwater that discharges to the streams that flow into the BB-LEH, in general, has shorter travel times, and a higher percentage of it originates in urban areas than does direct groundwater discharge to the Barnegat Bay–Little Egg Harbor estuary. The simulated average nitrogen concentration in groundwater that discharges to the Toms River, upstream from streamflow-gaging station 01408500 was computed and compared to summary concentrations determined from analysis of multiple surface-water samples. The nitrogen concentration in groundwater that discharges directly to the estuary and adjoining coastal wetlands is a current data gap. The particle tracking methodology used in this study provides an estimate of this concentration."

New Jersey↗
USGS2020

Magnitude and frequency of floods in Alabama, 2015

To improve flood-frequency estimates at rural streams in Alabama, annual exceedance probability flows at gaged locations and regional regression equations used to estimate annual exceedance probability flows at ungaged locations were developed by using current geospatial data, new analytical methods, and annual peak-flow data through September 2015 at 242 streamgages in Alabama and surrounding States. The regional regression equations were derived from statistical analyses of annual peak-flow data and basin characteristics for a subset of 217 streamgages. Four flood regions were identified based on residuals from the regional regression analyses and contain sites with similar basin characteristics. A separate set of equations was derived for estimating flood frequency and magnitude for small rural streams using a subset of 40 small basin streamgages. A large river analysis was also completed for 14 selected large-river streamgages in Alabama. Annual exceedance probability flows presented in this report reflect additional streamflow data collected since the previous study of flood magnitude and frequency in Alabama, which included streamflow through September 2003.

Alabama↗
USGS2021

Groundwater/surface-water interactions in the Partridge River Basin and evaluation of hypothetical future mine pits, Minnesota

The Partridge River Basin (PRB) covers 156 square miles in northeastern Minnesota with headwaters in the Mesabi Iron Range. The basin is characterized by extensive wetlands, lakes, and streams in poorly drained and often thin glacial material overlying Proterozoic bedrock. To better understand the interaction between these extensive surface water features and the groundwater system, a three-dimensional, steady-state, groundwater-flow model of the PRB was developed by the U.S. Geological Survey in cooperation with the Great Lakes Indian Fish & Wildlife Commission using the finite-difference computer code MODFLOW-NWT. The model simulates steady-state base flow in streams and groundwater interactions using the streamflow routing (SFR2) package. Existing mining features including tailings basins, stockpiles, pumped mine pits, and flooded mine pits were simulated using either high hydraulic conductivity zones or the drain (DRN) package. The unsaturated zone flow (UZF) package was used to better represent the groundwater system in areas with a high water table and for wetlands often associated with such areas. UZF typically is used to represent unsaturated zone processes but also can simulate the rejection of recharge and groundwater discharge to the land surface when the water table is near land surface. The steady-state model used data from the 2011 to 2013 period when 2011 high-resolution land surface (light detecting and ranging [lidar]) data were available that reflected land-surface and water elevations from mining activity in the basin. The parameter-estimation software suite PEST_HP was used to obtain a best fit of the modeled to measured groundwater levels, streamflow, pit inflow rates, and mapped peat deposits. The PEST calibration used the target residuals from two models with the same model parameters and targets from two separate periods: (1) a 1995–2015 calibration model, which provided a larger number of calibration targets, and (2) a 2011–2013 mining conditions model, which included calibration targets that reflected conditions consistent with the modeled mine-workings topography. Calibration of the PRB model resulted in ranges of glacial horizontal hydraulic conductivity parameters that generally agreed with literature values and other models of the region. Horizontal hydraulic conductivity of the bedrock was higher in the upper bedrock layers where numerous and continuous fractures have been observed and lower in the deeper bedrock layers. Average basin-wide calibrated infiltration was 5.3 inches per year. An average of 4.6 inches per year of infiltration crosses the water table and becomes recharge and 0.7 inch per year is rejected by UZF due to saturated conditions at the land surface. Simulated groundwater runoff (the sum of rejected recharge and groundwater seepage to the land surface) can either be routed to streams or removed from the model as evapotranspiration. The calibrated model indicates relatively shallow groundwater-flow paths dominating and approximately 50 percent of the stream base flow coming from groundwater runoff. The 2011–2013 mining conditions model was then used to develop five model scenarios simulating the response of the groundwater and surface-water system to potential hydrologic stress. The purpose of these mine pit scenarios is to present a possible workflow to quantify a model’s uncertainty for a given model forecast and serve as a possible guide for initial data collection that may improve a future model’s ability to make such a forecast. The scenarios included one scenario with the currently existing Peter Mitchell pit at final buildout and flooded to an elevation of 1,500 feet, and four scenarios with a hypothetical, new mine pit plus the flooded Peter Mitchell at final buildout. The five model scenarios were used to forecast streamflow at six locations in the PRB, pit inflow rates for the new mine pits and the flooded Peter Mitchell pit, and the average depth to water in 12 wetlands. A linear uncertainty analysis was performed using information from the PEST calibration and tools in the PyEMU python package to assess model uncertainty propagation to the model forecasts. Streamflows generally were reduced with future mining and the greatest streamflow reductions occurred from the flooded Peter Mitchell Pit, probably due to its large size. Average depth to groundwater in wetlands was most affected the closer the wetland was to a new mine pit. Linear uncertainty methods were also used to evaluate data worth, which is the ability for potential new groundwater elevation observations to reduce the uncertainty in scenario forecasts. Data worth was performed for a grid of new hydraulic head observations. Overall, areas with nonnegligible data worth generally corresponded to wetland areas with no groundwater seepage to land surface from UZF. These model behaviors indicated that the land-surface boundary condition simulated by the UZF package was pinning the groundwater elevations to the land surface in areas with groundwater seepage (33 percent of the 2011–2013 base conditions model) such that the sensitivity to new observations in these areas was minimal. Therefore, representing wetlands as boundary conditions minimized the usefulness of data worth calculations because wetland areas were present over a large part of the model domain. Probabilistic capture zones were estimated for each of the mines in the model scenarios. A capture zone represents the area contributing recharge to a model feature, like a well or a mine pit, and can be calculated by forward tracking particles from the water table. By using Monte Carlo techniques, it is possible to generate estimated capture zones that include the probability of recharge capture given the uncertainty present in the model. Monte Carlo techniques use randomly generated model parameter sets sampled from a plausible parameter range to create many possible realizations. The resulting capture zone arrays were calculated by tallying the total number of realizations in which a particle from a model cell was captured by the feature. Probabilities from the Monte Carlo runs ranged from 1 (captured in 100 percent of the runs) near the pits to 0 (captured in 0 percent of the runs) at the edges of the capture zone. Capture zones were not always spatially continuous; for example, the capture zone for the proposed mine pits south of the flooded Peter Mitchell pit was discontinuous with capture surrounding the proposed mine pit and north of the flooded Peter Mitchell pit. This northern section represents deeper groundwater flow paths that originate in the topographic high, move under the flooded pit, and discharge into the proposed pit. This pattern of capture indicates the possibility of some deeper flow through the upper fractured bedrock when the shallow groundwater flow system is modified. These results underscore that future site-specific applications of the base condition model require the input of site-specific data and recalibration to focus on the site of interest.

Minnesota↗
USGS2022

Lake Tahoe clarity and associated conditions, 2022

Lake Tahoe’s clarity remains a key indicator of overall ecosystem status, and scientific understanding about factors affecting lake clarity continues to evolve. The purpose of this briefing memorandum is to summarize the status of clarity metrics and drivers of change discussed in the 2022 TSAC Data Synthesis and Analysis report. Consistent with the Lake Tahoe Total Maximum Daily Load analyses, the concentrations of fine particles remain important to lake clarity. These include fine sediment particles from the watershed as well as small phytoplankton cells produced within the lake. This year, in addition to the analysis of Secchi depth clarity response to fine particle and small phytoplankton concentrations, we reviewed available data on fine sediment particles from streams and urban runoff. Information summarized here is discussed further in the Tahoe Science Advisory Council (TSAC) Data Synthesis and Analysis reports (2022, 2021), the TSAC Lake Tahoe Seasonal and Long-Term Clarity Trend Analysis report (2020), and in annual State of the Lake reports produced by UC Davis Tahoe Environmental Research Center.

California, Nevada↗
USGS2016

Application of a Weighted Regression Model for Reporting Nutrient and Sediment Concentrations, Fluxes, and Trends in Concentration and Flux for the Chesapeake Bay Nontidal Water-Quality Monitoring Network, Results Through Water Year 2012

In the Chesapeake Bay watershed, estimated fluxes of nutrients and sediment from the bay’s nontidal tributaries into the estuary are the foundation of decision making to meet reductions prescribed by the Chesapeake Bay Total Maximum Daily Load (TMDL) and are often the basis for refining scientific understanding of the watershed-scale processes that influence the delivery of these constituents to the bay. Two regression-based flux and trend estimation models, ESTIMATOR and Weighted Regressions on Time, Discharge, and Season (WRTDS), were compared using data from 80 watersheds in the Chesapeake Bay Nontidal Water-Quality Monitoring Network (CBNTN). The watersheds range in size from 62 to 70,189 square kilometers and record lengths range from 6 to 28 years. ESTIMATOR is a constant-parameter model that estimates trends only in concentration; WRTDS uses variable parameters estimated with weighted regression, and estimates trends in both concentration and flux. WRTDS had greater explanatory power than ESTIMATOR, with the greatest degree of improvement evident for records longer than 25 years (30 stations; improvement in median model R 2 = 0.06 for total nitrogen, 0.08 for total phosphorus, and 0.05 for sediment) and the least degree of improvement for records of less than 10 years, for which the two models performed nearly equally. Flux bias statistics were comparable or lower (more favorable) for WRTDS for any record length; for 30 stations with records longer than 25 years, the greatest degree of improvement was evident for sediment (decrease of 0.17 in median statistic) and total phosphorus (decrease of 0.05). The overall between-station pattern in concentration trend direction and magnitude for all constituents was roughly similar for both models. A detailed case study revealed that trends in concentration estimated by WRTDS can operationally be viewed as a less-constrained equivalent to trends in concentration estimated by ESTIMATOR. Estimates of annual mean flow-adjusted (ESTIMATOR) and flow-normalized (WRTDS) concentration for years initially constituting the end of a water-quality record showed a similar degree of variability as data for additional years were incrementally added and the initial estimates “aged.” On the basis of the results of this broad comparison of the two models, the U.S. Geological Survey is adopting WRTDS as the primary model for estimating constituent fluxes and trends throughout the CBNTN. Nutrient and sediment flux and trend estimates, based on WRTDS, are summarized narratively and tabulated in appendixes for all stations for which fluxes or trends were reported through water year 2012. WRTDS also was used to explore the sensitivity of flux and trend estimates to three data-quality issues common in many large-scale monitoring networks and evident in some of the CBNTN records. The potential effects of inconsistency in annual sampling effort and inconsistency in storm sampling effort were explored by way of a subsampling experiment using eight of the most densely sampled long-term (1985–2012) stations in the CBNTN as baseline datasets. From each dataset, a set of 10 “design guideline” subsamples was selected, consisting of 12 monthly samples and 8 targeted storm samples per year. The selection was conducted in a manner that preserved the overall intensity of storm sampling in the baseline data. These 10 subsamples were further manipulated to create “heterogeneous” subsamples by removing storm samples prior to 2003. The maximum relative difference between flow-normalized flux estimated in a single year from any of the 10 design guideline subsamples and values estimated in the corresponding year from baseline data was smallest for dissolved inorganic nitrogen (median of 8 stations = 6 percent of baseline estimate), but more appreciable for total phosphorus and sediment (medians of 22 and 32 percent, respectively). The maximum relative difference between flow-normalized flux estimated from from the 10 heterogeneous subsamples and values estimated in the corresponding year from baseline data was more pronounced, with medians for 8 stations of 15, 30, and 53 percent of the corresponding baseline estimates for dissolved inorganic nitrogen, total phosphorus, and sediment, respectively. The worst-case maximum relative differences between flow-normalize flux estimated in a single year from the 10 heterogeneous subsamples and values estimated in the corresponding year from baseline data were 25 percent for dissolved inorganic nitrogen, 37 percent for total phosphorus, and 250 percent for sediment. The results for the heterogeneous subsamples indicate that changes in storm sampling frequency can result in appreciable distortion of estimated trends in flow-normalized flux, especially for total phosphorus and sediment. Trend lines estimated from heterogeneous subsamples tended to converge with the trend lines estimated from baseline data after 2003. In contrast, 2003–12 trends based on subsamples truncated by discarding all data prior to the induced heterogeneity in 2003 showed appreciable biases and differences in slope, relative to the corresponding 2003–12 segment of the trend computed from the design guideline subsamples. Overall, the results indicate that for particulate constituents, load and trend estimates computed using long-term records recently converted to CBNTN design guideline sampling protocols will be most reliable if the trend is computed using the entire record, but reported only for the period that design guideline sampling protocols were followed. Inconsistencies related to changing laboratory methods were also examined via two manipulative experiments. In the first experiment, increasing and decreasing “stair-step” patterns of changes in censoring level, overall representing a factor-of-five change in the laboratory reporting limit, were artificially imposed on a 27-year record with no censoring and a period-of-record concentration trend of –68.4 percent. Trends estimated on the basis of the manipulated records were broadly similar to the original trend (–63.6 percent for decreasing censoring levels and –70.3 percent for increasing censoring levels), lending a degree of confidence that the survival regression routines upon which WRTDS is based are generally robust to data censoring. The second experiment considered an abrupt disappearance of low-concentration observations of total phosphorus, associated with a laboratory method change and not reflected through censoring, near the middle of a 28-year record. By process of elimination, an upward shift in the estimated flow-normalize concentration trend line around the same time was identified as a likely artifact resulting from the laboratory method change, although a contemporaneous change in watershed processes cannot be ruled out. Decisions as to how to treat records with potential sampling protocol or laboratory methods-related artifacts should be made on a case-by-case basis, and trend results should be appropriately qualified.

Maryland, New York, Pennsylvania, Virginia↗
USGS2007

Quaternarymagmatism in the Cascades - Geologic perspectives

Foreward The Cascade magmatic arc is a belt of Quaternary volcanoes that extends 1,250 km from Lassen Peak in northern California to Meager Mountain in Canada, above the subduction zone where the Juan de Fuca Plate plunges beneath the North American Plate. This Professional Paper presents a synthesis of the entire volcanic arc, addressing all 2,300 known Quaternary volcanoes, not just the 30 or so visually prominent peaks that comprise the volcanic skyline. Study of Cascade volcanoes goes back to the geological explorers of the late 19th century and the seminal investigations of Howel Williams in the 1920s and 1930s. However, major progress and application of modern scientific methods and instrumentation began only in the 1970s with the advent of systematic geological, geophysical, and geochemical studies of the entire arc. Initial stimulus from the USGS Geothermal Research Program was enhanced by the USGS Volcano Hazards Program following the 1980 eruption of Mount St. Helens. Together, these two USGS Programs have provided more than three decades of stable funding, staffing, and analytical support. This Professional Paper summarizes the resultant USGS data sets and integrates them with the parallel contributions of other investigators. The product is based upon an all-encompassing and definitive geological database, including chemical and isotopic analyses to characterize the rocks and geochronology to provide the critical time constraints. Until now, this massive amount of data has not been summarized, and a systematic and uniform interpretation firmly grounded in geological fact has been lacking. Herein lies the primary utility of this Cascade volume. It not only will be the mandatory starting point for new workers, but also will provide essential geological context to broaden the perspectives of current investigators of specific Cascade volcanoes. Wes Hildreth's insightful understanding of volcanic processes and his uncompromising scientific integrity make him uniquely qualified to present this synthesis. During more than three decades of volcanological studies, he has carried out comprehensive investigations of Mount Adams, Mount Baker, the Three Sisters, and the Simcoe Mountains Volcanic Field. He also brings a broad experience in other volcanic arcs, having conducted integrated field and laboratory investigations at several major volcanic centers in the Andes and the Aleutian arcs. His expertise and perspective have been further enhanced by in-depth petrologic studies of caldera environments, primarily in Long Valley, California, and Yellowstone. On the basis of all these field and laboratory investigations and exhaustive literature searches, he has published three definitive petrologic syntheses addressing the passage and transformation of basaltic magmas from their mantle sources through the crust to form the many types of volcanic manifestations at the Earth's surface. A major strength of this Professional Paper is that it adheres to data first and foremost, and only then correlates these data with relevant theories. Petrological and geophysical interpretation is left to the later sections of the volume, and even there is never allowed to stray from the pertinent databases. Hildreth's interpretations are not just idle speculations, but are carefully reasoned inferences firmly based on his thorough evaluation of the observational geological data. Professional Paper 1744 should not be skimmed lightly, in the hope that the salient points will quickly rub off. Instead, every section, indeed every paragraph, presents scholarly observations and insightful interpretations that demand careful and thoughtful study. This volume will influence and guide the course of Cascade investigations for decades to come.

British Columbia, California, Oregon, Washington↗
USGS2019

A hydrogeomorphic classification of connectivity of large rivers of the Upper Midwest, United States

River connectivity is defined as the water-mediated exchange of matter, energy, and biota between different elements of the riverine landscape. Connectivity is an especially important concept in large-river corridors (channel plus floodplain ) because large rivers integrate fluxes of water, sediment, nutrients, contaminants, and other transported constituents emanating from large contributing drainage basins, and thereby contribute to the complexity of large-river ecosystems. Large rivers are also highly valued for socioeconomic goods and services, which has led to historical fragmentation, lack of connectivity, and contentiousness about best policies for managing large-river corridors. The classification is intended to serve as a template for understanding geographic variation in large rivers within the Midwest, to aid in designing scientific studies of large river ecological processes, and to match specific river-management and restoration objectives to specific river reaches. The focus of the classification is on measuring river connectivity from available hydrological and geomorphic data. We provide a multiscale assessment and classification for segments of 15 rivers that meet various criteria for largeness. All rivers are tributaries to the Mississippi River system. The 11,600 kilometers (km) that qualified as large were classified by major alterations (unimpounded, navigation pools, storage reservoir) and additionally assessed for their network continuity as a function of numbers and heights of dams. Among the 15 rivers, 55 percent of segment length was unimpounded, 30 percent was in navigation pools, and 15 percent was under storage reservoirs. Assessment of network longitudinal connectivity among river segments documented the contrast between river segments with low-head navigation dams (Upper Mississippi, Illinois, Ohio, Green, and Cumberland Rivers) and those segments with high-head dams (mostly in the Upper Missouri River). The longest unimpounded river pathways exist in the Lower Missouri River and connected tributaries where nearly 1,300 km of the Missouri River connect to an additional 1,800 km of the Middle and Lower Mississippi Rivers. At our finest scale, we present a statistically based, component classification based on 10-km segments. Cluster analysis of hydrologic variables from 66 streamflow-gaging stations yielded 5 clusters calculated from 5 ecohydrological metrics related to lateral connectivity with the floodplain. A separate cluster analysis of 5 geomorphologic variables associated with each of the 1,172 river segments also yielded 5 clusters. When the hydrologic variables were associated with corresponding segments, the cluster analysis yielded 8 hydrogeomorphic clusters that could be explained in terms of their contribution to floodplain connectivity. Although the clusters overlap considerably in principal component space, the resulting hydrogeomorphic classification leads to a physically reasonable distribution of classes. The resulting classification is intended to increase geographic awareness of the range of variation of connectivity potential among large rivers of the Upper Midwest, to increase understanding of the extent of alteration of these rivers, and potentially to serve as a template for stratifying study designs of large-river corridor ecological processes.

Colorado, Illinois, Indiana, Iowa, Kansas, Kentuck↗
USGS2006

FGDC Digital Cartographic Standard for Geologic Map Symbolization (PostScript Implementation)

PLEASE NOTE: This now-approved 'FGDC Digital Cartographic Standard for Geologic Map Symbolization (PostScript Implementation)' officially supercedes its earlier (2000) Public Review Draft version (see 'Earlier Versions of the Standard' below). In August 2006, the Digital Cartographic Standard for Geologic Map Symbolization was officially endorsed by the Federal Geographic Data Committee (FGDC) as the national standard for the digital cartographic representation of geologic map features (FGDC Document Number FGDC-STD-013-2006). Presented herein is the PostScript Implementation of the standard, which will enable users to directly apply the symbols in the standard to geologic maps and illustrations prepared in desktop illustration and (or) publishing software. The FGDC Digital Cartographic Standard for Geologic Map Symbolization contains descriptions, examples, cartographic specifications, and notes on usage for a wide variety of symbols that may be used on typical, general-purpose geologic maps and related products such as cross sections. The standard also can be used for different kinds of special-purpose or derivative map products and databases that may be focused on a specific geoscience topic (for example, slope stability) or class of features (for example, a fault map). The standard is scale-independent, meaning that the symbols are appropriate for use with geologic mapping compiled or published at any scale. It will be useful to anyone who either produces or uses geologic map information, whether in analog or digital form. Please be aware that this standard is not intended to be used inflexibly or in a manner that will limit one's ability to communicate the observations and interpretations gained from geologic mapping. In certain situations, a symbol or its usage might need to be modified in order to better represent a particular feature on a geologic map or cross section. This standard allows the use of any symbol that doesn't conflict with others in the standard, provided that it is clearly explained on the map and in the database. In addition, modifying the size, color, and (or) lineweight of an existing symbol to suit the needs of a particular map or output device also is permitted, provided that the modified symbol's appearance is not too similar to another symbol on the map. Be aware, however, that reducing lineweights below .125 mm (.005 inch) may cause symbols to plot incorrectly if output at higher resolutions (1800 dpi or higher). For guidelines on symbol usage, as well as on color design and map labeling, please refer to the standard's introductory text. Also found there are informational sections covering concepts of geologic mapping and some definitions of geologic map features, as well as sections on the newly defined concepts and terminology for the scientific confidence and locational accuracy of geologic map features. More information on both the past development and the future maintenance of the FGDC Digital Cartographic Standard for Geologic Map Symbolization can be found at the FGDC Geologic Data Subcommittee website (http://ngmdb.usgs.gov/fgdc_gds/). Earlier Versions of the Standard

Techniques and Methods↗
USGS1997

Pesticides in surface waters: distribution, trends, and governing factors

Pesticde use in agriculture and non-agriculture settings has increased dramatically over the last several decades. Concern about adverse effects on the environment and human health has spurred an enormous amount of research into their environmental behavior and fate. Pesticides in Surface Waters presents a comprehensive summary of this research. This book evaluates published studies that focus on measuring pesticide concentration. The studies chosen include peer reviewed scientific literature, government reports, laboratory studies, and those using microcosms and artificial streams and ponds. The authors used this information to develop their overview of pesticide contamination of surface waters. The exhaustive compilation of data along with the fundamental science make this book essential for those involved in pesticide use, environmental protection, water quality, and human or ecological risk assessment. Pesticides in Surface Waters covers the results of actual studies, sources of pesticides to surface water, fate and transport, and environmental significance. Hundreds of data-packed tables, maps, charts, and drawings illustrate the key points, making research and application easy and cost effective.

Book↗
USGS2021

Streambank erosion and related geomorphic change in Tuolumne Meadows, Yosemite National Park, California

Landscape change in Tuolumne Meadows, Yosemite National Park, California, was characterized using data derived from four lidar surveys: one airborne survey in 2006 and three terrestrial surveys in 2016, 2017, and 2018. These surveys were used to generate a better quantitative understanding of changes associated with fluvial processes along the reach of the Tuolumne River within Tuolumne Meadows. This research was performed to provide a scientific basis for restoration and management decisions made by the National Park Service in accordance with the Tuolumne Wild and Scenic River Final Comprehensive Management Plan. A total of 15 reaches of the streambanks along the Tuolumne River in Tuolumne Meadows were subject to measurable streambank erosion between 2006 and 2018. In these areas, streambank retreat rates ranged between 0 and 2.7 meters per year (m/yr), recorded as an average retreat distance along the length of changing streambank position, with most retreat rates being less than 0.50 m/yr. The highest streambank retreat rates are associated with a year of high spring streamflow in 2017. Based on the data available, it was concluded that deposition on channel and point bars balances streambank erosion over a period of 12 years along the Tuolumne River in Tuolumne Meadows. As such, the river could be considered to be in a state of dynamic equilibrium during this period; erosion and sedimentation occur in distinct pulses in response to hydrological forcing but it is not clear that there is a trend towards sediment accumulation or removal in Tuolumne Meadows nor is there an obvious trend toward channel widening or narrowing. The existence of visible paleochannels in the meadow are an indication that more dramatic channel planform geometry changes have occurred in Tuolumne Meadows over an undetermined period and may occur again in the future. Geomorphic change rates relate to hydrology; during the study period, the high water in 2017 led to the highest rates of geomorphic change. Land managers should anticipate that floods with discharge rates greater than the peak flow in 2017 may cause more substantial landscape change than what was observed in this study, but erosion resulting from these events may be balanced by channel and point-bar deposition over a period of years.

California↗
USGS2023

Open water dreissenid mussel control projects: Lessons learned from a retrospective analysis

Dreissenid mussels are one of the most problematic aquatic invasive species (AIS) in North America, causing substantial ecological and economic effects. To date, dreissenid mussel control efforts in open water have included physical, biological, and chemical methods. The feasibility of successful dreissenid mussel management or eradication in lakes is relatively undocumented in the freshwater management literature. This review presents information on 33 open water dreissenid mussel control projects in 23 North America lakes. We reviewed data from past dreissenid mussel control projects and identified patterns and knowledge gaps to help inform adaptive management strategies. The three key lessons learned include (1) pre- and post-treatment survey methods that are designed to meet management objectives are beneficial, e.g., by sampling for all life stages and taking into account that no survey method is completely comprehensive; (2) defining the treatment area—particularly ensuring it is sufficiently large to capture all life stages present—is critical to meeting management objectives; and (3) control projects provide an opportunity to collect water chemistry, effects on non-target organisms, and other efficacy-related data that can inform safe and effective adaptive management.

Scientific Reports↗
USGS2004

Earthquakes and faults in the San Francisco Bay area (1970-2003)

The map depicts both active and inactive faults and earthquakes magnitude 1.5 to 7.0 in the greater San Francisco Bay area. Twenty-two earthquakes magnitude 5.0 and greater are indicated on the map and listed chronologically in an accompanying table. The data are compiled from records from 1970-2003. The bathymetry was generated from a digital version of NOAA maps and hydrogeographic data for San Francisco Bay. Elevation data are from the USGS National Elevation Database. Landsat satellite image is from seven Landsat 7 Enhanced Thematic Mapper Plus scenes. Fault data are reproduced with permission from the California Geological Survey. The earthquake data are from the Northern California Earthquake Catalog.

California↗
USGS2009

Sedimentation survey of Lago Guerrero, Aguadilla, Puerto Rico, March 2006

Lago Guerrero is located in Aguadilla, northwestern Puerto Rico (fig. 1). The reservoir has a surface area of about 32,000 square meters and is excavated in Aymamon Limestone of Miocene age. This bedrock consists of chalk interbed-ded with solution-riddled hard limestone (Monroe, 1969). The reservoir was constructed in the 1930s as part of the Isabela Hydroelectric System to regulate flows to two hydroelectric plants-Central Isabel No. 2, at an elevation of about 110 meters above mean sea level, and Central Isabel No. 3, at about 55 meters above mean sea level. Hydroelectric power generation was discontinued during the early 1960s, although the exact date is unknown (Puerto Rico Electric Power Authority, written commun., 2007). The principal use of the reservoir since then has been to regulate flow to two public-supply water filtration plants and supply irrigation water for the Aguadilla area. Flow into the reservoir is derived from Lago Guajataca through a 26-kilometer-long Canal Principal de Diversion concrete canal (Puerto Rico Electric Power Authority, written commun., 2001). Additional inflow occurs on an incidental basis only during intensive rainfall from the immediate drainage area. The present Lago Guerrero drainage area is undetermined, due to the irregular and complex topography of the limestone terrain and anthropogenic modifications to the stormwater drainage system. Stormwater runoff, however, is presumed to be negligible compared to the almost constant inflow to the reservoir of about 59,300 cubic meters per day from Lago Guajataca (CSA Group, 2000). On March 9, 2006, the U.S. Geological Survey (USGS), Caribbean Water Science Center, in cooperation with the Puerto Rico Electric Power Authority (PREPA), conducted a bathymetric survey of Lago Guerrero to determine the storage capacity of the reservoir and sedimentation amount since a previous survey conducted on May 30, 2001. The March 2006 survey was made to develop a bathymetric map of the reservoir, establish baseline data for future reservoir capacity comparisons, and to estimate the average sedimentation rate over the preceding 5 years.

Puerto Rico↗