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USGS1990

Water-quality trends and basin activities and characteristics for the Albemarle-Pamlico estuarine system, North Carolina and Virginia

The Albemarle-Pamlico estuarine system has a total basin area of nearly 31,000 square miles and includes the Neuse, Tar, Pamlico, Roanoke, Chowan, and Alligator Rivers, and the Albemarle, Pamlico, Currituck, Croatan, and Roanoke Sounds. Albemarle Sound receives the greatest freshwater inflow of all the sounds in the estuarine system. Inflow to this sound averages about 13,500 cubic feet per second. Inflow to Pamlico Sound from the Pamlico River averages around 5,400 cubic feet per second, and average inflow into the Neuse River estuary is about 6,100 cubic feet per second. Approximately one-half of the inflow into the system is from ground-water discharge. The Neuse River basin has had the greatest increases in wastewater discharges (650 percent since the 1950's) and had the greatesttotal wastewater discharges of any of the basins in the study area, averaging about 200 million gallons per day in 1988. Wastewater discharges into the Neuse and Tar Rivers were nearly equal to the 7-day, 10-year low flows for these rivers. Land-use data compiled in 1973 for the lower parts of the Neuse River basin and lower part of the Tar-Pamlico River basin indicate that 25 percent of the area was evergreen forest, 25 percent was forested wetlands, 20 percent was cropland and pasture, 12 percent was mixed forest, 10 percent was nonforested wetland, and 4 percent was urban. The amount of nonforested wetland in the part of the study area along the Outer Banks declined 6.5 percent from 1973 to 1983. The numbers of farms and acreage in agricultural use in the study area have declined since the 1920's. A decrease of more than 60 percentin the number of farms was shown between the early 1950's and 1982. Fertilizer sales increased through the 1970's, but declined in the 1980's. Manufacturing employment has increased in the last 30 years, while agricultural employment has decreased. Data from seven stations of the U.S. Geological Survey National Stream Quality Accounting Network were used to evaluate water quality for the major streams flowing into the Albemarle-Pamlico estuarine system. Water-quality data for 296 stations in the estuarine system were examined for the period 1945-88. The statistical test used for trend analysis was the Seasonal Kendall test (Hirsch and others, 1982). This nonparametric procedure is useful for analyses of water-quality properties that show non-normally distributed frequency distributions. The Seasonal Kendall trend analyses of water-quality data indicate that change has occurred in the water quality of the Albemarle-Pamlico estuarine system from 1945 to 1988. Dissolved-oxygen concentrations increased at a mean rate of 0.1 milligram per liter per year throughout the estuarine system, except in the Chowan River where decreases of approximately 0.06 milligram per liter per year occurred. In general, pH increased in streams throughout the area at a mean rate of 0.04 pH unit per year, except in the Pamlico River where pH decreased by 0.03 pH unit per year. A general increase in pH and dissolved-oxygen concentrations (if daytime measurements) might be indicative of more productive estuary conditions for algal growth. Suspended-solids concentrations decreased throughout the area at a mean rate of 1.1 milligrams per liter per year, probably as a result of a general decrease in suspended inorganic material. Increasing trends of salinity concentrations, as much as 0.1 part per thousand per year, were detected in Albemarle Sound. Total ammonia plus organic nitrogen concentrations decreased (-0.03 milligram per liter per year) in streams throughout most of the area but increased (0.02 milligram per liter per year) in the Pamlico River. However, ammonia nitrogen concentrations decreased (-0.0035 milligram per liter per year) in the Pamlico River; therefore, increases in organic nitrogen probably caused the observed increase in combined ammonia plus organic nitrogen concentrations. This probably results from increas

North Carolina, Virginia↗

USGS2013

Groundwater quality in the Madera and Chowchilla subbasins of the San Joaquin Valley, California

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s untreated groundwater quality and increases public access to groundwater-quality information. The Madera and Chowchilla subbasins of the San Joaquin Valley constitute one of the study units being evaluated. The Madera-Chowchilla study unit is about 860 square miles and consists of the Madera and Chowchilla groundwater subbasins of the San Joaquin Valley Basin (California Department of Water Resources, 2003; Shelton and others, 2009). The study unit has hot, dry summers and cool, moist winters. Average annual rainfall ranges from 11 to 15 inches, most of which occurs between November and February. The main surface-water features in the study unit are the San Joaquin, Fresno, and Chowchilla Rivers, and the Madera and Chowchilla canals. Land use in the study unit is about 69 percent (%) agricultural, 28% natural (mainly grasslands), and 3% urban. The primary crops are orchards and vineyards. The largest urban area is the city of Madera. The primary aquifer system is defined as those parts of the aquifer corresponding to the perforated intervals of wells listed in the California Department of Public Health (CDPH) database. In the Madera-Chowchilla study unit, these wells typically are drilled to depths between 200 and 800 feet, consist of a solid casing from land surface to a depth of about 140 to 400 feet, and are perforated below the solid casing. Water quality in the primary aquifer system may differ from that in the shallower and deeper parts of the aquifer system. The primary aquifer system in the study unit consists of Quaternary-age alluvial-fan and fluvial deposits that were formed by the rivers draining the Sierra Nevada. Sediments consist of gravels, sands, silts, and clays and generally are coarser closest to the Sierra Nevada and become finer towards the center of the basin. The structure and composition of the deposits in the Madera-Chowchilla study unit are different from those in other parts of the eastern San Joaquin Valley because the Fresno and Chowchilla Rivers primarily drain the Sierra Nevada foothills, whereas the larger rivers drain higher elevations with greater sediment supply. These differences in the sources of sediments are important because they may affect the groundwater chemistry and the physical structure of the sedimentary deposits. Some of the clay layers are lacustrine deposits, the most extensive of which, the Corcoran Clay, underlies the western part of the study unit and divides the primary aquifer system into an unconfined to semi-confined upper system and a largely confined lower system. Regional lateral flow of groundwater is southwest towards the valley trough. Irrigation return flows are the major source of groundwater recharge, and groundwater pumping is the major source of discharge. Groundwater on a lateral flow path may be repeatedly extracted by pumping wells and reapplied at the surface multiple times before reaching the valley trough, resulting in a substantial component of downward vertical flow (Burow and others, 2004; Phillips and others, 2007; Faunt, 2009). This flow pattern enhances movement of water from shallow depths to the primary aquifer system.

California↗

USGS2000

Summary of the major water-quality findings from the Eastern Iowa Basins study unit of the National Water-Quality Assessment Program

An integrated assessment of the water quality in streams and aquifers in the Wapsipinicon, Iowa, Cedar, and Skunk River basins was conducted in 1996 through 1998 as part of the Eastern Iowa Basins (EIWA) study unit of the U.S. Geological Survey's National Water-Quality Assessment Program (NAWQA). The EIWA study unit is one of 59 study units across the Nation designed to assess the status and trends in the quality of the Nation's ground- and surface-water resources and to link the status and trends with an understanding of the natural and human factors that affect the quality of water. Over 90 percent of the land in the EIWA study unit is used for agricultural purposes, while forested areas account for only 4 percent and urban areas about 2 percent of the land. Surface-water samples were collected monthly and during selected storm events from six sites in medium-sized basins (125 to about 400 mi2) and five sites in large river basins (2,300 to 12,500 mi2). The medium-sized basins were selected to be representative of various physical features, hydrogeology, and agricultural landuse (row crops and concentrated animal feeding operations) that may affect water quality. The large river sites were selected to determine the integrated effects of combinations of landuse and hydrogeology on river-water quality. Ground-water samples were collected primarily from the alluvial aquifers because of the aquifers' direct hydraulic connection with rivers and streams and because alluvial aquifers are one of the most important sources for domestic, municipal, and industrial water supplies in the study area. Monitoring wells were installed in agricultural and urban areas of the alluvial aquifers to assess the quality of the most recently recharged water in relation to land use. Existing domestic wells screened in alluvial aquifers and the Silurian/Devonian aquifer were sampled to assess deeper and older ground water. Surface- and ground-water samples were analyzed for a wide variety of chemical constituents (major ions, nutrients, and pesticides) commonly associated with agricultural and urban activities. Because they were not expected to occur in rivers and streams, volatile organic compounds (VOC's), commonly comprising fuels, solvents, and other industrial compounds were only analyzed in ground-water samples. The age of the ground water, important information needed to relate ground-water quality to land use, was determined using both tritium and chlorofluorocarbons (Freon?) age-dating methods. Results from the EIWA NAWQA study build on previous and ongoing research and water-quality monitoring programs in Iowa and provide new insights into the relation between the quality of the State's water resources and human activities. The major findings from the study are listed below.

Iowa↗

USGS1973

Role of water in urban planning and management

Concentrations of people in urban areas intensify water problems such as flooding and pollution, but these deleterious effects on water resources can be minimized or corrected by comprehensive planning and management. Such planning of the water resources of an urban area must be based on adequate hydrologic data. Through the use of a matrix, urban water problems can be evaluated and availability of data assessed. The Washington-Baltimore metropolitan area is used as a case study. The completed matrix provides both a means for developing a meaningful dialogue between the hydrologist and the urban planner and a method for developing a work plan to insure consideration of water-resources data in urban planning.

Maryland↗

USGS2018

Association between degradation of pharmaceuticals and endocrine-disrupting compounds and microbial communities along a treated wastewater effluent gradient in Lake Mead

The role of microbial communities in the degradation of trace organic contaminants in the environment is little understood. In this study, the biotransformation potential of 27 pharmaceuticals and endocrine-disrupting compounds was examined in parallel with a characterization of the native microbial community in water samples from four sites variously impacted by urban run-off and wastewater discharge in Lake Mead, Nevada and Arizona, USA. Samples included relatively pristine Colorado River water at the upper end of the lake, nearly pure tertiary-treated municipal wastewater entering via the Las Vegas Wash, and waters of mixed influence (Las Vegas Bay and Boulder Basin), which represented a gradient of treated wastewater effluent impact. Microbial diversity analysis based on 16S rRNA gene censuses revealed the community at this site to be distinct from the less urban-impacted locations, although all sites were similar in overall diversity and richness. Similarly, Biolog EcoPlate assays demonstrated that the microbial community at Las Vegas Wash was the most metabolically versatile and active. Organic contaminants added as a mixture to laboratory microcosms were more rapidly and completely degraded in the most wastewater-impacted sites (Las Vegas Wash and Las Vegas Bay), with the majority exhibiting shorter half-lives than at the other sites or in a bacteriostatic control. Although the reasons for enhanced degradation capacity in the wastewater-impacted sites remain to be established, these data are consistent with the acclimatization of native microorganisms (either through changes in community structure or metabolic regulation) to effluent-derived trace contaminants. This study suggests that in urban, wastewater-impacted watersheds, prior exposure to organic contaminants fundamentally alters the structure and function of microbial communities, which in turn translates into greater potential for the natural attenuation of these compounds compared to more pristine sites.

Arizona, Nevada↗

USGS2012

Contaminants in stream sediments from seven United States metropolitan areas: part II—sediment toxicity to the amphipod Hyalella azteca and the midge Chironomus dilutus

Relationships between sediment toxicity and sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toxic to midge based on comparisons with reference conditions within each study area. Significant correlations were observed between toxicity end points and sediment concentrations of trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or organochlorine (OC) pesticides; however, these correlations were typically weak, and contaminant concentrations were usually below sediment-toxicity thresholds. Concentrations of the pyrethroid bifenthrin exceeded an estimated threshold of 0.49 ng/g (at 1 % total organic carbon) in 14 % of the samples. Of the samples that exceeded this bifenthrin toxicity threshold, 79 % were toxic to amphipods compared with 25 % toxicity for the samples below this threshold. Application of mean probable effect concentration quotients (PECQs) based on measures of groups of contaminants (trace elements, total PAHs, total PCBs,OCpesticides, and pyrethroid pesticides [bifenthrin in particular]) improved the correct classification of samples as toxic or not toxic to amphipods compared with measures of individual groups of contaminants. Sediments are a repository for many contaminants released into surface waters. Because of this, organisms inhabiting sediments may be exposed to a wide range of contaminants (United States Environmental Protection Agency (USEPA) United States Environmental Protection Agency 2000; American Society for Testing and Materials [ASTM] American Society for Testing and Materials International 2012). Contaminants of potential concern in sediments typically include trace elements (metals), organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs; Ingersoll et al. 2001). In 2000, the USEPA began to restrict the use of organophosphate pesticides, such as diazinon and chlorpyrifos (Spurlock and Lee 2008). These restrictions have led to increased use of pyrethroid pesticides, which have widespread applications in both agricultural and urban environments (Kuivila et al. 2012). Pyrethroids are hydrophobic compounds that have been observed to accumulate in sediments (Laskowski 2002). Toxicity of pyrethroids in field-collected sediment from small urban streams (Weston et al. 2005; Holmes et al. 2008; Ding et al. 2010; Domagalski et al. 2010) or with pyrethroids spiked into sediment (Amweg et al. 2006; Hintzen et al. 2009) have been evaluated primarily in 10 day lethality tests conducted with the amphipod Hyalella azteca . However, the sublethal effects in long-term exposures to pyrethroids in sediment have not been evaluated, and the distribution of pyrethroids sediments has not typically been evaluated in wadeable streams (Gilliom et al. 2006). This article is the second in a series that describe the results of a study of the distribution and toxicity of pyrethroids and other co-occurring trace elements and organic contaminants (PCBs, PAHs, OC pesticides) in stream sediments from 7 metropolitan areas across the United States (Moran et al. 2012). The study evaluated 98 sediment samples collected from streams ranging from undeveloped to highly urban and differs from previous studies by sampling larger wadeable streams and avoiding point sources (such as storm drains) and other inflows (Gilliom et al. 2006). Part 1 of the series characterizes sediment contaminants in relation to urbanization and other factors in the 7 metropolitan study areas (Nowell et al. 2012). Part 2 (this article) evaluates relationships between sediment chemistry and sediment toxicity in 28 day whole-sediment exposures conducted with the amphipod H. azteca and in 10 day whole-sediment exposure conducted with the midge Chironomus dilutus (USEPA United States Environmental Protection Agency 2000; ASTM American Society for Testing and Materials International 2012). Toxicity end points evaluated in the amphipod and midge exposures included the effects of these field-collected sediments on survival, weight, or biomass of the test organisms.

Georgia;Massachusetts;Texas;Colorado;Wisconsin;Uta↗

USGS2018

Water-quality observations of the San Antonio segment of the Edwards aquifer, Texas, with an emphasis on processes influencing nutrient and pesticide geochemistry and factors affecting aquifer vulnerability, 2010–16

As questions regarding the influence of increasing urbanization on water quality in the Edwards aquifer are raised, a better understanding of the sources, fate, and transport of compounds of concern in the aquifer—in particular, nutrients and pesticides—is needed to improve water management decision-making capabilities. The U.S. Geological Survey, in cooperation with the San Antonio Water System, performed a study from 2010 to 2016 to better understand how water quality changes under a range of hydrologic conditions and in contrasting land-cover settings (rural and urban) in the Edwards aquifer. The study design included continuous hydrologic monitoring, continuous water-quality monitoring, and discrete sample collection for a detailed characterization of water quality at a network of sites throughout the aquifer system. The sites were selected to encompass a “source-to-sink” (that is, from aquifer recharge to aquifer discharge) approach. Network sites were selected to characterize rainfall, recharging surface water, and groundwater; groundwater sites included wells in the unconfined part of the aquifer (unconfined wells) and in the confined part of the aquifer (confined wells) and a major discharging spring. Storm-related samples—including rainfall samples, stormwater-runoff (surface-water) samples, and groundwater samples—were collected to characterize the aquifer response to recharge. Elevated nitrate concentrations relative to national background values and the widespread detection of pesticides indicate that the Edwards aquifer is vulnerable to contamination and that vulnerability is affected by factors such as land cover, aquifer hydrogeology, and changes in hydrologic conditions. Greater vulnerability of groundwater in urban areas relative to rural areas was evident from results for urban groundwater sites, which generally had higher nitrate concentrations, elevated δ 15 N-nitrate values, a greater diversity of pesticides, and higher pesticide concentrations. The continuum of water quality from unconfined rural groundwater sites (least affected by anthropogenic contamination) to unconfined urban groundwater sites (most affected by anthropogenic contamination) demonstrates enhanced vulnerability of urban versus rural land cover. Differences in contaminant occurrences and concentration among unconfined urban wells indicate that the urban parts of the aquifer are not uniformly vulnerable, but rather are affected by spatial differences in the sources of nutrients and pesticides. In urban areas, the shallow, unconfined groundwater sites showed greater temporal variability in both nutrient and pesticide concentrations, as well as a greater degree of contamination, than did deeper, confined groundwater sites. In comparison to that of the shallow, unconfined groundwater sites, the water quality of the deeper, confined groundwater sites was relatively invariant during this multiyear study. Although aquifer hydrogeology is an important factor related to aquifer vulnerability, land cover likely has a greater influence on pesticide contamination of groundwater. Temporal variability in hydrologic conditions for the Edwards aquifer is apparent in data for surface water as a source of groundwater recharge, water-level altitude in wells, spring discharge, and groundwater quality. This temporal variability affects recharge sources, recharge amounts, groundwater traveltimes, flow routing, water-rock interaction processes, dilution, mixing, and, in turn, water quality. Relations of land cover, aquifer hydrogeology, and changing hydrologic conditions to water quality are complex but provide insight into the vulnerability of Edwards aquifer groundwater—a vital drinking-water resource.

Texas↗

USGS2025

Land use change consistently reduces α‐ but not β‐ and γ‐diversity of bees

Land use change threatens global biodiversity and compromises ecosystem functions, including pollination and food production. Reduced taxonomic α-diversity is often reported under land use change, yet the impacts could be different at larger spatial scales (i.e., γ-diversity), either due to reduced β-diversity amplifying diversity loss or increased β-diversity dampening diversity loss. Additionally, studies often focus on taxonomic diversity, while other important biodiversity components, including phylogenetic diversity, can exhibit differential responses. Here, we evaluated how agricultural and urban land use alters the taxonomic and phylogenetic α-, β-, and γ-diversity of an important pollinator taxon—bees. Using a multicontinental dataset of 3117 bee assemblages from 157 studies, we found that taxonomic α-diversity was reduced by 16%–18% in both agricultural and urban habitats relative to natural habitats. Phylogenetic α-diversity was decreased by 11%–12% in agricultural and urban habitats. Compared with natural habitats, taxonomic and phylogenetic β-diversity increased by 11% and 6% in urban habitats, respectively, but exhibited no systematic change in agricultural habitats. We detected a 22% decline in taxonomic γ-diversity and a 17% decline in phylogenetic γ-diversity in agricultural habitats, but γ-diversity of urban habitats was not significantly different from natural habitats. These findings highlight the threat of agricultural expansions to large-scale bee diversity due to systematic γ-diversity decline. In addition, while both urbanization and agriculture lead to consistent declines in α-diversity, their impacts on β- or γ-diversity vary, highlighting the need to study the effects of land use change at multiple scales.

Global Change Biology↗

USGS2012

Spatial and temporal patterns of surface water quality and ichthyotoxicity in urban and rural river basins in Texas

The Double Mountain Fork Brazos River (Texas, USA) consists of North (NF) and South Forks (SF). The NF receives urban runoff and twice-reclaimed wastewater effluent, whereas the SF flows through primarily rural areas. The objective of this study was to determine and compare associations between standard water quality variables and ichthyotoxicity at a landscape scale that included urban (NF) and rural (SF) sites. Five NF and three SF sites were sampled quarterly from March 2008 to March 2009 for specific conductance, salinity, hardness, pH, temperature, and turbidity; and a zebrafish ( Danio rerio ) embryo bioassay was used to determine ichthyotoxicity. Metal and nutrient concentrations at all sites were also measured in addition to standard water quality variables in spring 2009. Principal component analyses identified hardness, specific conductance, and salinity as the water variables that best differentiate the urban NF (higher levels) from rural SF habitat. Nutrient levels were also higher in the NF, but no landscape scale patterns in metal concentrations were observed. Ichthyotoxicity was generally higher in NF water especially in winter, and multiple regression analyses suggested a positive association between water hardness and ichthyotoxicity. To test for the potential influence of the toxic golden alga ( Prymnesium parvum ) on overall ichthyotoxicity, a cofactor known to enhance golden alga toxin activity was used in the bioassays. Golden alga ichthyotoxicity was detected in the NF but not the SF, suggesting golden alga may have contributed to overall ichthyotoxicity in the urban but not in the rural system. In conclusion, the physicochemistry of the urban-influenced NF water was conducive to the expression of ichthyotoxicity and also point to water hardness as a novel factor influencing golden alga ichthyotoxicity in surface waters.

Texas↗

USGS2006

Land use/land cover change effects on temperature trends at U.S. Climate Normals stations

Alterations in land use/land cover (LULC) in areas near meteorological observation stations can influence the measurement of climatological variables such as temperature. Urbanization near climate stations has been the focus of considerable research attention, however conversions between non-urban LULC classes may also have an impact. In this study, trends of minimum, maximum, and average temperature at 366 U.S. Climate Normals stations are analyzed based on changes in LULC defined by the U.S. Land Cover Trends Project. Results indicate relatively few significant temperature trends before periods of greatest LULC change, and these are generally evenly divided between warming and cooling trends. In contrast, after the period of greatest LULC change was observed, 95% of the stations that exhibited significant trends (minimum, maximum, or mean temperature) displayed warming trends. Copyriht 2006 by the American Geophysical Union.

Geophysical Research Letters↗

USGS2022

Bayesian applications in environmental and ecological studies with R and Stan

Modern ecological and environmental sciences are dominated by observational data. As a result, traditional statistical training often leaves scientists ill-prepared for the data analysis tasks they encounter in their work. Bayesian methods provide a more robust and flexible tool for data analysis, as they enable information from different sources to be brought into the modelling process. Bayesian Applications in Evnironmental and Ecological Studies with R and Stan provides a Bayesian framework for model formulation, parameter estimation, and model evaluation in the context of analyzing environmental and ecological data. Features: An accessible overview of Bayesian methods in environmental and ecological studies Emphasizes the hypothetical deductive process, particularly model formulation Necessary background material on Bayesian inference and Monte Carlo simulation Detailed case studies, covering water quality monitoring and assessment, ecosystem response to urbanization, fisheries ecology, and more Advanced chapter on Bayesian applications, including Bayesian networks and a change point model Complete code for all examples, along with the data used in the book, are available via GitHub The book is primarily aimed at graduate students and researchers in the environmental and ecological sciences, as well as environmental management professionals. This is a group of people representing diverse subject matter fields, who could benefit from the potential power and flexibility of Bayesian methods.

Book↗

USGS2003

Nitrogen emissions, deposition, and monitoring in the Western United States

Nitrogen (N) deposition in the western United States ranges from 1 to 4 kilograms (kg) per hectare (ha) per year over much of the region to as high as 30 to 90 kg per ha per year downwind of major urban and agricultural areas. Primary N emissions sources are transportation, agriculture, and industry. Emissions of N as ammonia are about 50% as great as emissions of N as nitrogen oxides. An unknown amount of N deposition to the West Coast originates from Asia. Nitrogen deposition has increased in the West because of rapid increases in urbanization, population, distance driven, and large concentrated animal feeding operations. Studies of ecological effects suggest that emissions reductions are needed to protect sensitive ecosystem components. Deposition rates are unknown for most areas in the West, although reasonable estimates are available for sites in California, the Colorado Front Range, and central Arizona. National monitoring networks provide long-term wet deposition data and, more recently, estimated dry deposition data at remote sites. However, there is little information for many areas near emissions sources.

BioScience↗

USGS2020

Physical and chemical stressors on algal, invertebrate, and fish communities in 14 Milwaukee area streams, 2004–2013

In 2004, the U.S. Geological Survey (USGS) began sampling 14 wadable streams in urban or urbanizing watersheds near Milwaukee, Wisconsin. The overall goal of the study is to assess the health of the aquatic communities in the Milwaukee Metropolitan Sewerage District planning area to inform current and future watershed management. In addition to collection of biological data on aquatic communities, physical and chemical data were also collected to evaluate effects of potential environmental stressors on the aquatic communities. This fact sheet summarizes the primary results of the study from 2004 to 2013. Detailed information is described in Scudder Eikenberry and others (2020a), and all data are available in Scudder Eikenberry and others (2020b; https://doi.org/10.5066/P9FWMODL ).

Wisconsin↗

USGS2004

Baseline Characteristics of Jordan Creek, Juneau, Alaska

Anadromous fish populations historically have found healthy habitat in Jordan Creek, Juneau, Alaska. Concern regarding potential degradation to the habitat by urban development within the Mendenhall Valley led to a cooperative study among the City and Borough of Juneau, Alaska Department of Environmental Conservation, and the U.S. Geological Survey, that assessed current hydrologic, water-quality, and physical-habitat conditions of the stream corridor. Periods of no streamflow were not uncommon at the Jordan Creek below Egan Drive near Auke Bay stream gaging station. Additional flow measurements indicate that periods of no flow are more frequent downstream of the gaging station. Although periods of no flow typically were in March and April, streamflow measurements collected prior to 1999 indicate similar periods in January, suggesting that no flow conditions may occur at any time during the winter months. This dewatering in the lower reaches likely limits fish rearing and spawning habitat as well as limiting the migration of juvenile salmon out to the ocean during some years. Dissolved-oxygen concentrations may not be suitable for fish survival during some winter periods in the Jordan Creek watershed. Dissolved-oxygen concentrations were measured as low as 2.8 mg/L at the gaging station and were measured as low as 0.85 mg/L in a tributary to Jordan Creek. Intermittent measurements of pH and dissolved-oxygen concentrations in the mid-reaches of Jordan Creek were all within acceptable limits for fish survival, however, few measurements of these parameters were made during winter-low-flow conditions. One set of water quality samples was collected at six different sites in the Jordan Creek watershed and analyzed for major ions and dissolved nutrients. Major-ion chemistry showed Jordan Creek is calcium bicarbonate type water with little variation between sampling sites.

Open-File Report↗

USGS1980

Ground-water hydrology of James City County, Virginia

Urbanization and increase in water demand prompted a 2-year study of groundwater availability and quality in the county of James City. The coastal-plain sediments, parts of which underlie the county, are the largest source of groundwater in Virginia. Four aquifers form the complex aquifer system. Hydraulic characteristics vary from aquifer to aquifer and from place to place. The Cretaceous aquifer furnishes nearly all the water for industrial and municipal needs. Movement of water in the Cretaceous aquifer is toward cones of depression formed by pumping centers at Williamsburg and Dow Badische Co. All aquifers contain water that generally meets State standards for drinking water. Water in the Cretaceous aquifer is of the sodium chloride bicarbonate type. As depth of aquifer increases, the concentrations of dissolved solids and chloride also increase. Saline water (more than 250 milligrams per liter) occupies the deeper parts of the confined aquifers. The amount of water stored in the coastal sediments is estimated to be 650-1300 billion gallons. An increase in pumpage to accommodate the expected daily demand of 9.8 million gallons per day in year 2000 is feasible provided pumpage is distributed over the county. (USGS)

Open-File Report↗

USGS1998

Water-level changes (1975-98) in the Antelope Valley, California

Antelope Valley is in the western part of the Mojave Desert in southern California, about 50 mi northeast of Los Angeles. Between 1975 and 1998, water levels in the valley have changed in response to a shift in ground-water use from agricultural to urban, declining in some areas and rising in others. A study to document these changes was conducted by the U.S. Geological Survey in cooperation with the Antelope Valley Water Group. This report presents the water-level data and the changes that occurred during this study period.

California↗

USGS2002

Fecal-indicator bacteria in the Yakima River Basin, Washington: An examination of 1999 and 2000 synoptic-sampling data and their relation to historical data

The Yakima Basin National Water-Quality Assessment Program collected fecal-coliform bacteria samples during three synoptic samplings to identify and quantify the cause, source, transport, and effects of fecal-indicator bacteria in Yakima River Basin streams. The August 1999 synoptic sampling targeted the Yakima River main-stem and tributary sites, while the July and October-November 2000 synoptic samplings targeted small- and intermediate-sized agricultural watersheds during irrigation and nonirrigation season, respectively. Quality-assurance results indicated that variability in fecal-coliform concentrations is large and, therefore, a difference of an order of magnitude or more between sites or between times is required for the values to be significantly different 90 percent of the time. The August 1999 synoptic sampling results indicated that (1) 44 percent of the sites visited, including all the main-stem Yakima River sites, met the Class A fecal-coliform 90th percentile standard of 200 colonies per deciliter, (2) tributaries were the likely source of fecal contamination to the main stem, and (3) tributaries with high fecal-coliform concentrations typically also had high suspended-sediment concentrations. Results of the July and October-November 2000 synoptic samplings indicated that (1) 36 and 81 percent of the sites sampled, respectively, met the standard, (2) during the nonirrigation synoptic sampling, four of the six sites not meeting the standard were from the Granger and Sulphur subbasins, and (3) fecal-coliform concentrations during the irrigation season were generally higher than during the nonirrigation season. Several levels of temporal variability were examined. The short-term variability observed during a synoptic sampling was found to be site specific, with some sites fairly consistent, while others were rather variable. Seasonally, most sites from the 2000 synoptic samplings showed higher concentrations during irrigation than during nonirrigation. Historically, 13 of the 22 sites sampled during both the July 1988 and August 1999 synoptic samplings had higher concentrations in 1999. The three sites with the highest concentrations in July 1988, however, all had decreases in August 1999. When compared against historical (1972-85) minimum and maximum summer-month medians, the August 1999 synoptic-sampling concentrations generally were between these values. Instantaneous fecal-coliform bacteria loads were calculated for the August 1999 synoptic sampling in an effort to study the dynamics of bacterial transport. Tributaries affected by agricultural, urban, and hobby farm activities were generally the major sources of bacteria to the main-stem Yakima River during this time. When these August 1999 synoptic-sampling loads in the lower basin reach from the Yakima River at river mile 72 to Kiona (river mile 29.9) were compared to those from the July 1988 synoptic sampling, most sites had higher loads in 1999. A nonparametric Spearman test was used to detect correlations between fecal-coliform concentrations and physical and chemical data collected during the synoptic samplings. Results for the August 1999 synoptic sampling, which included many mouths of tributaries, showed strong significant correlations with almost every variable. In contrast, only some of the nutrient concentrations showed strong significant correlations during the July and October-November 2000 synoptic samplings, which included small and intermediate- sized agricultural streams. Looking forward relative to future monitoring goals, research needs, and best management practice development, four hypotheses that deal with processes and sources of bacteria were identified: (1) overland runoff transports bacteria from land surfaces to streams, (2) bacteria in the water column tend to associate with suspended matter, (3) with increasing densities of warm-blooded animals, the likelihood of fecal-coliform contamination in streams also increases, and (4) identifi- cation of bacterial sources is difficult, but must be attempted for remediation to be possible.

Washington↗

USGS2012

Groundwater quality in the Indian Wells Valley, California

California↗