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At least 523 records · Page 29Linked to original sources
USGS1987

Surface water-quality assessment of the Kentucky River basin, Kentucky: Project description

In April 1986, the U.S. Geological Survey began the National Water Quality Assessment Program, which at present (1987) is in a pilot phase in which assessment concepts and approaches are being tested and modified to prepare for full implementation of the program in the future. Seven pilot projects (four surface water projects and three groundwater projects) have been started. The preliminary plans for the surface water quality assessment of the Kentucky River basin pilot project are described. The Kentucky River basin drains an area of approximately 7,000 sq mi in east central Kentucky and is underlain by rocks that range in composition from limestone to sandstone and shale. Because greater than 95% of the basin population relies on surface water, surface water quality is of great concern. Land use practices that affect the surface water quality in the basin include agriculture, forestry, oil and gas production, coal mining, and urbanization. Water quality concerns resulting from the various land uses include the effects of: oil and gas field brine discharges; agricultural chemicals; sedimentation caused by coal mining; and trace element impacts from industrial and urban environments. Assessment activity is designed to occur over a 9-year period of time. During the first 3-year period of the cycle, concentrated data acquisition and interpretation will occur. For the next 6 years, sample collection will occur at a much lower level of intensity to document the occurrence of any gross changes in water quality. This 9-year cycle will then be repeated. Historical data will be evaluated to provide, to the extent possible, a description of existing and past trends in water quality conditions and to develop conceptual models that relate the observed conditions to the sources and causes, both natural and human-controlled. New data will be collected to verify the water quality conditions documented by historic data, to track long-term trends in water quality, to intensify temporal and spatial sampling densities, and to improve the understanding of the relations between water quality conditions and causative factors. (Lantz-PTT)

Kentucky↗
USGS1997

Ecosystem history of South Florida; Biscayne Bay sediment core descriptions

The 'Ecosystem History of Biscayne Bay and the southeast Coast' project of the U.S. Geological Survey is part of a multi-disciplinary effort that includes Florida Bay and the Everglades to provide paleoecologic reconstructions for the south Florida region. Reconstructions of past salinity, nutrients, substrate, and water quality are needed to determine ecosystem variability due to both natural and human-induced causes. Our understanding of the relations between the south Florida ecosystem and introduced forces will allow managers to make informed decisions regarding the south Florida ecosystem restoration and monitoring. The record of past ecosystem conditions can be found in shallow sediment cores. This U.S. Geological Survey Open-File Report describes six shallow sediment cores collected from Biscayne Bay. The cores described herein are being processed for a variety of analytical procedures, and this provides the descriptive framework for future analyses of the included cores. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Open-File Report↗
USGS1997

Progress report on sediment analyses at selected faunal monitoring sites in north-central and northeastern Florida Bay

Florida Bay is a shallow, subtropical lagoon at the southern tip of the Florida peninsula. The 2200 square kilometer, triangular-shaped area is the site of modern carbonate sediment formation and deposition. The intricate ecosystem of the bay has undergone significant changes as the result of natural influences and human intervention. The purpose of this study is to investigate carbonate sediment characteristics and distribution in conjunction with faunal and floral to determine the substrate preferences of associated fauna and flora. The modern data provide the proxy data for down-core analyses of sediments, fauna and flora in order to document ecosystem changes in the bay. Selected sediment samples collected during 1996 from 18 sites in the northeastern and central bay were analyzed for insoluble residues, organic content, total carbonate, and percent of silt and clay sized particles. Insoluble residues range from 0.8% of the sediment in a shell lag to 11.5% with an average of 5.1%. Organic content ranged from a minimum of 1.43% of the sediment to 18.05% with an average of 7.6%. The total carbonate content ranged from 72.56% to 97.81%, averaging 87.98%. The percent silt and clay sized particles ranged from 13.75% to 63.62% for the samples analyzed. The insoluble residue content shows a general trend of decreasing insoluble residues from the northeastern bay toward the southwest. Organic content is variable throughout the bay and does not show a regional trend. Several sites show a trend of higher organic content in the samples collected in February as compared to those collected in July. Lithologic examination indicated that, in addition to the carbonate mud (less than 63mm), sample components included whole and fragmented mollusks, foraminifers, bryozoans, ostracods, and organic matter. The insoluble residues consisted of quartz sand and silt, clays and siliceous fossils. A component of the insoluble residues may be dust derived from Africa and transported to southern Florida by the prevailing winds. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Open-File Report↗
USGS2008

Land area change in coastal Louisiana: A multidecadal perspective (from 1956 to 2006)

The U.S. Geological Survey (USGS) analyzed changes in the configuration of land and water in coastal Louisiana by using a sequential series of 14 data sets summarizing land and water areas from 1956 to 2006. The purpose of this study is to provide a spatially and temporally consistent source of quantitative information on land area across coastal Louisiana, broken into three physiographic provinces (the term 'coastal Louisiana' is used to present data on the collective area). The land-water data sets used in this study are interpreted through spatial analysis and by linear regression analysis. The spatial depictions of land area change reveal a complex and interwoven mosaic of loss and gain patterns caused by natural and human-induced processes operating at varied temporal and spatial scales, resulting in fluctuating contributions to coastal loss. The linear regression analysis provides a robust estimate of recent change trends by comparing land area over time for all data sets from 1985 to 2004 and from 1985 to 2006 by physiographic province across coastal Louisiana. The 1956 to 2006 map showing multidecadal changes, along with the linear regressions of land area change presented in this study, provide a comprehensive and concise presentation of historical trends and rates of land area change in coastal Louisiana. Taking a broad historical view provides an in-depth understanding of land area changes over time. For example, one observation provided by our historical review is that the majority of the widespread, nontransitory land gains depicted on the map over the past 50 years, with the exception of the progradation of the Atchafafalaya River and Wax Lake deltas, are primarily related to sediment placement and landward migration of barrier islands. Another point revealed by our historical approach is that recent land losses caused by hurricanes sometimes commingled with or exacerbated older losses formed during the 1956 to 1978 period. Furthermore, our analyses also show how the immediate impacts of extreme storms can alter the long-term, time-averaged trends of landscape change, thus limiting the range of projections for the future. For this reason, this study does not include trend projections beyond 2015 because of uncertainties related to recovery from the 2005 hurricane season and the potential for other episodic events that could skew future rates of change.

Louisiana↗
USGS2009

Preliminary Map of Landslide Deposits in the Mesa Verde National Park Area, Colorado

This report presents a preliminary map of landslide deposits in the Mesa Verde National Park area (see map sheet) at a compilation scale of 1:50,000. Landslide is a general term for landforms produced by a wide variety of gravity-driven mass movements, including various types of flows, slides, topples and falls, and combinations thereof produced by the slow to rapid downslope transport of surficial materials or bedrock. The map depicts more than 200 landslides ranging in size from small (0.01 square miles) earthflows and rock slumps to large (greater than 0.50 square miles) translational slides and complex landslides (Varnes, 1978). This map has been prepared to provide a regional overview of the distribution of landslide deposits in the Mesa Verde area, and as such constitutes an inventory of landslides in the area. The map is suitable for regional planning to identify broad areas where landslide deposits and processes are concentrated. It should not be used as a substitute for detailed site investigations. Specific areas thought to be subject to landslide hazards should be carefully studied before development. Many of the landslides depicted on this map are probably stable as they date to the Pleistocene (approximately 1.8-0.011 Ma) and hence formed under a different climate regime. However, the recognition of these landslides is important because natural and human-induced factors can alter stability. Reduction of lateral support (by excavations or roadcuts), removal of vegetation (by fire or development), or an increase in pore pressure (by heavy rains) may result in the reactivation of landslides or parts of landslides.

Scientific Investigations Map↗
USGS2004

Simulation of the ground-water-flow system in the Kalamazoo County area, Michigan

A ground-water-flow model was developed to investigate the ground-water resources of Kalamazoo County. Ground water is widely used as a source of water for drinking and industry in Kalamazoo County and the surrounding area. Additionally, lakes and streams are valued for their recreational and aesthetic uses. Stresses on the ground-water system, both natural and human-induced, have raised concerns about the long-term availability of ground water for people to use and for replenishment of lakes and streams. Potential changes in these stresses, including withdrawals and recharge, were simulated using a ground-water-flow model. Simulations included steady-state conditions (in which stresses remained constant and changes in storage were not included) and transient conditions (in which stresses changed in seasonal and monthly time scales and storage within the system was included). Steady-state simulations were used to investigate the long-term effects on water levels and streamflow of a reduction in recharge or an increase in pumping to projected 2010 withdrawal rates, withdrawal and application of water for irrigation, and a reduction in recharge in urban areas caused by impervious surfaces. Transient simulations were used to investigate changes in withdrawals to match seasonal and monthly patterns under various recharge conditions, and the potential effects of the use of water for irrigation over the summer months. With a reduction in recharge, simulated water levels declined over most of the model area in Kalamazoo County; with an increase in pumping, water levels declined primarily near pumping centers. Because withdrawals by wells intercept water that would have discharged possibly to a stream or lake, model simulations indicated that streamflow was reduced with increased withdrawals. With withdrawal and consumption of water for irrigation, simulated water levels declined. Assuming a reduction in recharge due to urbanization, water levels declined and flow to streams was reduced based on steady-state simulation results. Transient results indicated a reduction of water levels with the simulated use of water for irrigation over the summer months. Generally the transient simulation with recharge only in the winter provided the best fit to observed water levels collected during synoptic water-level measurements in some wells and to the trends observed in water levels for other wells. Analysis of the regional hydrologic budgets provides an increased understanding of water movement within the ground-water-flow system in Kalamazoo County. Budgets for the steady-state simulations indicated that with reduced recharge, less water was available for streamflow and less water left the model area through the model boundaries. Similarly, with an increase in pumping rates, less water was available to enter streams and become streamflow. When recharge was assumed to remain constant and when it was allowed to vary throughout the year, the amount of water that entered storage was greater than that which left storage. However, when recharge was distributed through October?May only or when recharge rates were reduced from October to May, the amount of water that entered storage was less than that which left storage. Thus, on the basis of model simulations, with reduced recharge or increased withdrawals, water must come from storage, rivers, or from ground-flow-system boundaries to meet withdrawal demands.

Michigan↗
USGS2006

Methane gas concentration in soils and ground water, Carbon and Emery Counties, Utah, 1995-2003

The release of methane gas from coal beds creates the potential for it to move into near-surface environments through natural and human-made pathways. To help ensure the safety of communities and determine the potential effects of development of coal-bed resources, methane gas concentrations in soils and ground water in Carbon and Emery Counties, Utah, were monitored from 1995 to 2003. A total of 420 samples were collected, which contained an average methane concentration of 2,740 parts per million by volume (ppmv) and a median concentration of less than 10 ppmv. On the basis of spatial and temporal methane concentration data collected during the monitoring period, there does not appear to be an obvious, widespread, or consistent migration of methane gas to the near-surface environment.

Utah↗
USGS2008

Streamflow and Topographic Characteristics of the Platte River near Grand Island, Nebraska, 1938-2007

The central Platte River is a dynamic, braided, sand-bed river located near Grand Island, Nebraska. An understanding of the Platte River channel characteristics, hydrologic flow patterns, and geomorphic conditions is important for the operation and management of water resources by the City of Grand Island. The north channel of the Platte River flows within 1 mile of the municipal well field, and its surface-water flow recharges the underlying aquifer, which serves as a water source for the city. Recharge from the north channel helps minimize the flow of contaminated ground water from the north of the channel towards the well field. In recent years the river channels have experienced no-flow conditions for extended periods during the summer and fall seasons, and it has been observed that no-flow conditions in the north channel often persist after streamflow has returned to the other three channels. This potentially allows more contaminated ground water to move toward the municipal well field each year, and has caused resource managers to ask whether human disturbances or natural geomorphic change have contributed to the increased frequency of no-flow conditions in the north channel. Analyses of aerial photography, channel surveys, Light Detection and Ranging data, discharge measurements, and historical land surveys were used to understand the past and present dynamics of the four channels of the Platte River near Grand Island and to detect changes with time. Results indicate that some minor changes have occurred in the channels. Changes in bed elevation, channel location, and width were minimal when compared using historical information. Changes in discharge distribution among channels indicate that low- and no-flow conditions in the north channel may be attributed to the small changes in channel characteristics or small elevation differences, along with recent reductions in total streamflow within the Platte River near Grand Island, or to factors not measured in this study, such as increased channel roughness from increased vegetation within the channel.

Scientific Investigations Report↗
USGS2016

A spatially explicit suspended-sediment load model for western Oregon

We calibrated the watershed model SPARROW (Spatially Referenced Regressions on Watershed attributes) to give estimates of suspended-sediment loads for western Oregon and parts of northwestern California. Estimates of suspended-sediment loads were derived from a nonlinear least squares regression that related explanatory variables representing landscape and transport conditions to measured suspended-sediment loads at 68 measurement stations. The model gives estimates of model coefficients and their uncertainty within a spatial framework defined by the National Hydrography Dataset Plus hydrologic network. The resulting model explained 64 percent of the variability in suspended-sediment yield and had a root mean squared error value of 0.737. The predictor variables selected for the final model were (1) generalized lithologic province, (2) mean annual precipitation, and (3) burned area (by recent wildfire). Other landscape characteristics also were considered, but they were not significant predictors of sediment transport, were strongly correlated with another predictor variable, or were not as significant as the predictors selected for the final model. The northern Oregon coastal drainages had the highest predicted suspended sediment yields (median yield 475 kilograms per hectare per year) and the Klamath River Basin had the lowest (median yield 53 kilograms per hectare per year). Quaternary deposits were, on average, the largest contributor to incremental suspended-sediment yield even though this lithologic province only makes up 17 percent of the modeling domain. Coast Range sedimentary rocks and Coast Range volcanic rocks had high suspended-sediment yields whereas, in addition to the Klamath terrane, the Western Cascade and High Cascade lithologic provinces had low suspended-sediment yields. Precipitation and the area affected by recent wildfire both positively correlated with suspended-sediment load. Suspended-sediment transport rates predicted by this SPARROW model are less than historical (1956–73) and long‑term (thousands of years) geological rates. This difference likely results, in part, from biases in the data underlying the SPARROW model, probably resulting in predicted suspended-sediment estimates that underestimate actual transport rates. However, the differences also likely owe to natural and human-caused variation in suspended-sediment yields as they respond to changes in climate, vegetation, fire frequency, and land use. In particular, decreases in mean annual suspended-sediment yields within the Umpqua River Basin since 1956–73 may owe to less intense forest harvest, passage of the Oregon Forest Practices Act of 1971, and increased emphasis in habitat protection in recent decades. Such sensitivity may have implications for the spatial and temporal distributions of aquatic and riparian habitats. Knowledge of the regionally important patterns and factors in suspended-sediment sources and transport could support broad-scale, water-quality management objectives and priorities. Because of biases and limitations of this model, however, these results are most applicable for general comparisons and for broad areas such as large watersheds. For example, despite having similar area, precipitation, and land-use, the Umpqua River Basin generates 68 percent more suspended sediment than the Rogue River Basin, chiefly because of the large area of Coast Range sedimentary province in the Umpqua River Basin. By contrast, the Rogue River Basin contains a much larger area of Klamath terrane rocks, which produce significantly less suspended load, although recent fire disturbance (in 2002) has apparently elevated suspended sediment yields in the tributary Illinois River watershed. Fine-scaled analysis, however, will require more intensive, locally focused measurements.

Scientific Investigations Report↗
USGS2024

Correlation analysis of groundwater and hydrologic data, Kaloko-Honokōhau National Historical Park, Hawai‘i

Designated in 1978, Kaloko-Honokōhau National Historical Park is located on the west coast of the Island of Hawaiʻi. The Kaloko-Honokōhau National Historical Park encompasses about 1,200 acres of coastal land and nearshore ecosystems, which include wetlands, anchialine pools (landlocked bodies of brackish water with hydrologic connections to the ocean), fishponds, a fishtrap, and coral reefs. These nearshore ecosystems are dependent on groundwater discharge with a freshwater component and provide habitat for threatened and endangered, endemic species, such as the orangeblack Hawaiian damselfly ( Megalagrion xanthomelas ) and the Hawaiian coot (ʻAlae keʻokeʻo, Fulica alai ). The populations of these native species, however, are threatened because of habitat loss related to urban development and environmental changes. Kaloko-Honokōhau National Historical Park is within the Keauhou aquifer system and the North Kona District, which experienced a 52 percent resident-population increase between 2000 and 2020 and a 41 percent visitor increase between 2008 and 2019. To support the current water demand associated with this growing population, groundwater is the primary source of freshwater used in the North Kona District, with about 15 million gallons of groundwater withdrawn from the Keauhou aquifer system per day since 2009. With anticipated development, future (2015–35) groundwater withdrawal from the Keauhou aquifer system is projected to be about 55 percent greater than recent (2012–14) withdrawal. Because Kaloko-Honokōhau National Historical Park is located within a coastal aquifer, natural and human-induced changes can affect the quality and quantity of groundwater, which can threaten groundwater-dependent ecosystems. To improve understanding of recent groundwater conditions, the U.S. Geological Survey, in cooperation with the National Park Service, undertook this study to document correlations between hydrologic time-series datasets from sites in and near Kaloko-Honokōhau National Historical Park using the nonparametric (distribution-free) Kendall’s tau statistical test. For the statistical analyses, dependent variables representing the groundwater system include groundwater level, the groundwater-level difference between pairs of sites, and specific conductance, and independent variables include datasets of sea level, rainfall, and groundwater withdrawal. About 34 percent of the 140 non-time-lagged Kendall’s tau statistical tests evaluated in this report are statistically significant ( p -value ≤ 0.050) with generally weak (0.1 ≤ tau ≤ 0.2) to moderate (0.2 ≤ tau ≤ 0.3) correlations. Groundwater levels measured at monitoring sites have the strongest correlation with the multivariate El Niño–Southern Oscillation index and withdrawal from production wells at the nearby Kohanaiki Private Club Community. Specific conductance is not consistently and significantly correlated with the independent hydrologic variables investigated in this report. Because the relations between hydrologic variables are commonly not instantaneous, a second set of correlations was evaluated after applying a range of time lags to the independent variable datasets. Relative to the non-time-lagged case (the set of correlations that did not use time-lagged independent variables), some of the time-lagged independent variables improved correlations with some of the dependent variables. For a particular independent variable, similar time lags were expected between the independent variable and dependent variable at all four monitoring sites. However, different time lags among the four sites sometimes produced the strongest correlations. This study identified several correlations that are statistically significant and hydrologically plausible, but the correlations could indicate that multiple concurrent factors are controlling the observed groundwater-system response, which might be better addressed using multivariate analyses. This study only investigates bivariate correlations, which may not explain all the variance in the data. The correlations analyzed in this report are limited by the quantity of available hydrologic data in the area near Kaloko-Honokōhau National Historical Park and are based on 14 years of time-series data, which were aggregated to a relatively coarse monthly temporal resolution that represents the minimum resolution common to all datasets.

Hawaii↗
USGS2024

Societal benefits of cyanobacteria harmful algal bloom management in Lake Okeechobee in Florida—Potential damages avoided during the 2018 event under U.S. Army Corps of Engineers Harmful Algal Bloom Interception, Treatment, and Transformation System scenarios

Freshwater harmful algal blooms (HABs) formed by blue-green algae, or cyanobacteria, have emerged as a global environmental problem. Their negative impacts on aquatic ecosystems can affect the benefits nature provides to human society by reducing water quality; inhibiting aquatic recreation; killing fish, wildlife, and pets; and posing a risk to human health. To manage harmful algal blooms, the Engineer Research and Development Center of the U.S. Army Corps of Engineers is developing an advanced technology called the Harmful Algal Bloom Interception, Treatment, and Transformation System (HABITATS), which has been tested in pilot demonstrations upstream of spillways at HAB-affected waterbodies in Florida. The U.S. Geological Survey and cooperators from the U.S. Department of the Interior Office of Policy Analysis investigated the societal benefits of HABITATS technology by using data from an actual 2018 harmful algal bloom in Lake Okeechobee to characterize the observed societal impacts and then comparing observed effects to hypothetical scenarios of HABITATS deployment. This study estimated an economic value of $5.5 million in foregone recreation as a result of closed boating ramp facilities and other restrictions on aquatic recreation such as fishing and swimming during the 2018 cyanobacteria harmful algal bloom outbreak. The change in housing sales prices that could have resulted from murky water or bad odor during that outbreak was estimated as $2.3 million. The team also investigated drinking water contamination and human illness but did not find significant societal impacts in this case. If HABITATS had been deployed, the avoided losses less the cost of management could have provided net societal benefits that ranged between negative $2.1 million and positive $0.8 million, depending on the vertical distribution of algae in the water column and the HABITATS version used. The study’s estimated societal benefit is undoubtedly a lower bound estimate because current scientific knowledge is inadequate to characterize, or monetize, all the impacts.

Florida↗
USGS2025

A trend analysis and model comparison of total phosphorus concentrations and loads in the Boise River near Parma, southwestern Idaho, water years 2003–21

Total phosphorus (TP) concentrations and loads in the Boise River near Parma, Idaho, were examined to identify changes by month over a 19-year period from water year 2003 through water year 2021 and to evaluate the performance of three common water-quality models. Mean annual TP concentrations and loads were estimated to have reduced by approximately 60 percent over the study period. Mean annual TP concentrations were reduced from 0.42 milligrams per liter in 2003 to 0.18 milligrams per liter in 2021. Mean annual TP loads were reduced from 816 kilograms per day in 2003 to 302 kilograms per day in 2021. Mean annual concentrations and loads reduced by approximately 3 percent per year with the largest changes occurring in the non-irrigation season of October through April. The TP load remained highest in May across the model period while peak concentration shifted from January to March. High-frequency TP data collected with an automated sampler every 49 hours enabled detailed model performance evaluation of the Load Estimator (LOADEST), Weighted Regressions on Time, Discharge, and Season (WRTDS), and WRTDS method with Kalman filtering (WRTDS_K) water-quality models generated with near-monthly data. All three models were generally able to reproduce the observed concentrations, with the largest errors occurring in the spring when observed concentrations were most variable. Annual TP loads varied by up to 27 percent, or approximately 128,000 kilograms, between the three models calibrated on monthly data. In this system with highly variable concentrations, we note that performance metrics for WRTDS_K based on monthly calibration data masked serious errors that were only revealed by comparing results against higher frequency (49-hour) autosampler data. This emphasizes the value of high frequency validation data to quantify uncertainty in water-quality models when applied to systems where concentrations change rapidly. Lastly, we identify that hydraulic routing may be a valuable addition to discharge, season, and time in water-quality modeling for systems with significant human intervention in natural hydro-biogeochemical processes.

Idaho↗
USGS2024

Semi-automated methods to develop a unified geographic information system dataset

Geospatial data describing the topography, natural features, human-built features, and land uses of a particular area or region can come from independent data providers and, therefore, vary in format, data encoding, and geographic coverage. Because of the complexity of the processes and procedures required for unifying these heterogeneous data into a dataset with consistent format, encoding, and coverage, fully automated procedures for data unification do not exist. However, a combination of manual and automated procedures—semi-automated methods—can substantially reduce the time required for data unification while improving accuracy. This report presents three semi-automated data-unification methods in detail. Although these methods are not new in principle, their details are the result of original development work, and they serve as examples that can be reused, adapted, or generalized to provide head starts to future data-unification projects. The format of this report can be used and refined to encourage the publication of future reports and more widespread sharing of semi-automated methods.

Techniques and Methods↗
USGS2026

RoadxStr user’s guide—For collection of road-stream crossing assessment field observations

Intersections of drainage networks and road networks represent a critical nexus between natural waterways and human infrastructure. Managing these systems involves decisions related to management of infrastructure, hydrologic and geomorphic processes, and ecological connectivity. Interactions among these systems influence multiple values, including the intactness of transportation networks, public safety, water quality, and ecosystem function that collectively amount to billions of dollars. Despite the importance of road-stream crossings, there are countless gaps in knowing where and what they are. These gaps limit the degree to which managers can inventory and assess stream and road networks to inform decisions. To address this first-level need, we developed RoadxStr (road-stream crossings): a survey tool that effectively characterizes road-stream crossings across the full stream and drainage network. This document describes the RoadxStr Field Form, available within a mobile application, which is designed for rapid and standardized data collection involving assessment of a road-stream crossing, including the road, crossing structure(s), and the nearby hydrologic channel. This document provides instructions on how to (1) access and download the RoadxStr Field Form within the mobile application service and (2) use and complete a RoadxStr Field Form survey.

Techniques and Methods↗
USGS2006

Chapter A6. Section 6.2. Dissolved oxygen

Accurate data for the concentration of dissolved oxygen in surface and ground waters are essential for documenting changes in environmental water resources that result from natural phenomena and human activities. Dissolved oxygen is necessary in aquatic systems for the survival and growth of many aquatic organisms and is used as an indicator of the health of surface-water bodies. This section of the National Field Manual (NFM) includes U.S. Geological Survey (USGS) guidance and protocols for four methods to determine dissolved-oxygen concentrations: the amperometric, luminescent-sensor, spectrophotometric, and iodometric (Winkler) methods. Each chapter of the National Field Manual is published separately and revised periodically. Newly published and revised chapters will be announced on the USGS Home Page on the World Wide Web under 'New Publications of the U.S. Geological Survey.'

Techniques of Water-Resources Investigations↗
USGS2002

Water-quality and aquatic-community characteristics of selected reaches of the St. Croix River, Minnesota and Wisconsin, 2000

Synoptic sampling was used to determine chemical and biological characteristics of the St. Croix River within a study reach that extended from near Danbury, Wisconsin to the confluence with the Mississippi River at Prescott, Wisconsin. The study was conducted August 7- September 25, 2000 during summer low flow. Dissolved-residue concentrations were found to increase gradually as the river flows downstream, with an abrupt increase downstream of the confluence with the Sunrise River that was primarily attributed to an increase in calcium and magnesium. Dissolved residue concentrations were further augmented by increased yields of chloride and sulfate in the part of the St. Croix Basin between Nevers Dam near St. Croix Falls, Wisconsin and Marine on St. Croix, Minnesota. Nearly all of the nitrogen in transport was in the form of nitrate and organic nitrogen. Organic nitrogen, mainly in particulate form, accounted for most of the gain in total nitrogen load within the study reach. Nitrogen loading to the mainstem indicated relatively uniform nitrogen inputs from the Clam River, Kettle River, and Snake River watersheds. The rate of nitrogen load accrual increased downstream of the confluence with the Sunrise River and in the subreach extending from Nevers Dam through St. Croix Falls to Franconia, Minnesota. Nitrogen load also increased, primarily because of nitrate input, in the part of Lake St. Croix downstream of the confluence with the Kinnickinnic River. Total phosphorus concentrations and loads reflected variations in the amount of particulate phosphorus in transport. Phosphorus loading increased in the part of the St. Croix River that includes Danbury and the confluences of the Yellow River and Clam River. Phosphorus loading also increased downstream of the confluence with the Sunrise River, but the greatest load increase occurred between Nevers Dam and Franconia. Phosphorus load decreased substantially as the river flowed through the pooled reach of Lake St. Croix downstream of Stillwater. Suspended-sediment concentrations were low, ranging from 4.0 to 36 milligrams per liter. The small amount of sediment in transport was reflected in turbidity measurements that ranged from 0.5 to 3.6 Nephelometry Turbidity Units, and transparency tube measurements that were greater than 60 centimeters at all sites. Biological measures of resource quality change in the St. Croix River along its course from Danbury to Prescott. Changes in the biological indicators of resource quality (fish and invertebrate community composition) are most notable just upstream and downstream of the dam at St. Croix Falls, Wisconsin. Aquatic communities in the upper St. Croix River, from near Danbury to near Rush City, Minnesota, indicate minimal physical and chemical disturbance as evidenced by relatively high taxa richness and greater proportions of taxa intolerant to physical and chemical disturbance. In contrast, aquatic communities downstream of the Sunrise River to Marine on St. Croix indicate both physical and chemical disturbance. Resource monitoring, consisting of short-term diagnostic studies, may be needed in parts of the St. Croix River mainstem and tributaries where results from this study indicate constituent loading is greatest and where the aquatic community composition indicates disturbance. Longer-term trend monitoring may be needed to detect physical, chemical and biological responses to natural processes and human activities in the St. Croix River Basin.

Minnesota, Wisconsin↗
USGS2003

Simulation of net infiltration and potential recharge using a distributed-parameter watershed model of the Death Valley region, Nevada and California

This report presents the development and application of the distributed-parameter watershed model, INFILv3, for estimating the temporal and spatial distribution of net infiltration and potential recharge in the Death Valley region, Nevada and California. The estimates of net infiltration quantify the downward drainage of water across the lower boundary of the root zone and are used to indicate potential recharge under variable climate conditions and drainage basin characteristics. Spatial variability in recharge in the Death Valley region likely is high owing to large differences in precipitation, potential evapotranspiration, bedrock permeability, soil thickness, vegetation characteristics, and contributions to recharge along active stream channels. The quantity and spatial distribution of recharge representing the effects of variable climatic conditions and drainage basin characteristics on recharge are needed to reduce uncertainty in modeling ground-water flow. The U.S. Geological Survey, in cooperation with the Department of Energy, developed a regional saturated-zone ground-water flow model of the Death Valley regional ground-water flow system to help evaluate the current hydrogeologic system and the potential effects of natural or human-induced changes. Although previous estimates of recharge have been made for most areas of the Death Valley region, including the area defined by the boundary of the Death Valley regional ground-water flow system, the uncertainty of these estimates is high, and the spatial and temporal variability of the recharge in these basins has not been quantified. To estimate the magnitude and distribution of potential recharge in response to variable climate and spatially varying drainage basin characteristics, the INFILv3 model uses a daily water-balance model of the root zone with a primarily deterministic representation of the processes controlling net infiltration and potential recharge. The daily water balance includes precipitation (as either rain or snow), snow accumulation, sublimation, snowmelt, infiltration into the root zone, evapotranspiration, drainage, water content change throughout the root-zone profile (represented as a 6-layered system), runoff (defined as excess rainfall and snowmelt) and surface water run-on (defined as runoff that is routed downstream), and net infiltration (simulated as drainage from the bottom root-zone layer). Potential evapotranspiration is simulated using an hourly solar radiation model to simulate daily net radiation, and daily evapotranspiration is simulated as an empirical function of root zone water content and potential evapotranspiration. The model uses daily climate records of precipitation and air temperature from a regionally distributed network of 132 climate stations and a spatially distributed representation of drainage basin characteristics defined by topography, geology, soils, and vegetation to simulate daily net infiltration at all locations, including stream channels with intermittent streamflow in response to runoff from rain and snowmelt. The temporal distribution of daily, monthly, and annual net infiltration can be used to evaluate the potential effect of future climatic conditions on potential recharge. The INFILv3 model inputs representing drainage basin characteristics were developed using a geographic information system (GIS) to define a set of spatially distributed input parameters uniquely assigned to each grid cell of the INFILv3 model grid. The model grid, which was defined by a digital elevation model (DEM) of the Death Valley region, consists of 1,252,418 model grid cells with a uniform grid cell dimension of 278.5 meters in the north-south and east-west directions. The elevation values from the DEM were used with monthly regression models developed from the daily climate data to estimate the spatial distribution of daily precipitation and air temperature. The elevation values were also used to simulate atmosp

Water-Resources Investigations Report↗
USGS2004

Status of ground-water levels and storage volume in the Equus Beds aquifer near Wichita, Kansas, January 2000-January 2003

The Equus Beds aquifer northwest of Wichita, Kansas, was developed to supply water to Wichita residents and for irrigation in south-central Kansas beginning on September 1, 1940. Ground-water pumping for city and agricultural use from the aquifer caused water levels to decline in a large part of the area. Irrigation pumpage in the area increased substantially during the 1970s and 1980s and accelerated water-level declines. A period of water-level rises associated with greater-than-average precipitation and decreased city pumpage from the study area began in 1993. An important factor in the decreased city pumpage was increased use of Cheney Reservoir as a water-supply source by the city of Wichita; as a result, city pumpage from the Equus Beds aquifer during 1993-2002 went from being greater than one-half to slightly less than one-third of Wichita's water usage. Since 1995, the city also has been investigating the use of artificial recharge in the study area to meet future water-supply needs and to protect the aquifer from the intrusion of saltwater from natural and human-related sources to the west. During January 2003, the direction of ground-water flow in the Equus Beds aquifer in the area was generally from west to east similar to predevelopment of the aquifer. The maximum water-level decline since 1940 for the period January 2000 to January 2003 was 29.54 feet in July 2002 at well 3 in the northern part of the area. Cumulative water-level changes from January 2000 to January 2003 typically were less than 4 feet with rises of less than 4 feet common in the central part of the area; however, declines of more than 4 feet occurred in the northwestern and southern parts of the area. The recovery of water levels and aquifer storage volumes from record low levels in October 1992 generally continued to April 2000. The recovery of about 182,000 acre-feet of storage volume in the area from October 1992 to April 2000 represents about a 64-percent recovery of the storage depletion that occurred from August 1940 to October 1992. About 47 percent of this recovery was lost from April 2000 to October 2002 when storage volume in the area decreased by about 86,000 acre-feet. Major contributors to the decreases in water levels and storage volumes were reduced recharge associated with precipitation that was less than in the preceding 5 years and increased irrigation pumpage. The loss of storage probably would have been larger if the continued decrease in city pumpage, which is closely associated with the water-level rises in the central part of the study area, and increased city use of water from Cheney Reservoir had not occurred. The effect of artificial recharge on water levels and storage volume probably was masked by the generally larger decreases in city pumpage in the area.

Kansas↗