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At least 577 records · Page 32Linked to original sources
USGS2017

Spatial and temporal relationships between the invasive snail Bithynia tentaculata and submersed aquatic vegetation in Pool 8 of the Upper Mississippi River

Bithynia tentaculata is an invasive snail that was first reported in Lake Michigan in 1871 and has since spread throughout a number of freshwater systems of the USA. This invasion has been extremely problematic in the Upper Mississippi River as the snails serve as intermediate hosts for several trematode parasites that have been associated with waterfowl mortality in the region. This study was designed to assess the abundance and distribution of B . tentaculata relative to submersed aquatic vegetation as macrophytes provide important nesting and food resources for migrating waterfowl. Temporal changes in both vegetation and snail densities were compared between 2007 and 2015. Between these years, B . tentaculata densities have nearly quadrupled despite minor changes in vegetation abundance, distribution and composition. Understanding the spatial distribution of B . tentaculata in relation to other habitat features, including submersed vegetation, and quantifying any further changes in the abundance and distribution of B . tentaculata over time will be important for better identifying areas of risk for disease transmission to waterfowl.

River Research and Applications↗
USGS2020

Non-crop habitat use by wild bees (Hymenoptera: Apoidea) in a mixed-use agricultural landscape

Homogeneous, agriculturally intense landscapes have abundant records of pollinator community research, though similar studies in the forest-dominated, heterogeneous mixed-use landscape that dominates the northeastern United States are sparse. Trends of landscape effects on wild bees are consistent across homogeneous agricultural landscapes, whereas reported studies in the northeastern United States have not found this consistency. Additionally, the role of noncrop habitat in mixed-use landscapes is understudied. We assessed wild bee communities in the mixed-use lowbush blueberry ( Vaccinium angustifolium Ait.) production landscape of Maine, United States at 56 sites in eight land cover types across two regional landscapes and analyzed effects of floral resources, landscape pattern, and spatial scale on bee abundance and species richness. Within survey sites, cover types with abundant floral resources, including lowbush blueberry fields and urban areas, promoted wild bee abundance and diversity. Cover types with few floral resources such as coniferous and deciduous/mixed forest reduced bee abundance and species richness. In the surrounding landscape, lowbush blueberry promoted bee abundance and diversity, while emergent wetland and forested land cover strongly decreased these measures. Our analysis of landscape configuration revealed that patch mixing can promote wild bee abundance and diversity; however, this was influenced by strong variation across our study landscape. More surveys at intra-regional scales may lead to better understanding of the influence of mixed-use landscapes on bee communities.

Environmental Entomology↗
USGS2017

Assessing the impacts of future climate conditions on the effectiveness of winter cover crops in reducing nitrate loads into the Chesapeake Bay Watershed using SWAT model

Winter cover crops (WCCs) have been widely implemented in the Coastal Plain of the Chesapeake Bay watershed (CBW) due to their high effectiveness at reducing nitrate loads. However, future climate conditions (FCCs) are expected to exacerbate water quality degradation in the CBW by increasing nitrate loads from agriculture. Accordingly, the question remains whether WCCs are sufficient to mitigate increased nutrient loads caused by FCCs. In this study, we assessed the impacts of FCCs on WCC nitrate reduction efficiency on the Coastal Plain of the CBW using Soil and Water Assessment Tool (SWAT) model. Three FCC scenarios (2085 – 2098) were prepared using General Circulation Models (GCMs), considering three Intergovernmnental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) greenhouse gas emission scenarios. We also developed six representative WCC implementation scenarios based on the most commonly used planting dates and species of WCCs in this region. Simulation results showed that WCC biomass increased by ~ 58 % under FCC scenarios, due to climate conditions conducive to the WCC growth. Prior to implementing WCCs, annual nitrate loads increased by ~ 43 % under FCC scenarios compared to the baseline scenario (2001 – 2014). When WCCs were planted, annual nitrate loads were substantially reduced by ~ 48 % and WCC nitrate reduction efficiency water ~ 5 % higher under FCC scenarios relative to the baseline. The increase rate of WCC nitrate reduction efficiency varied by FCC scenarios and WCC planting methods. As CO2 concentration was higher and winters were warmer under FCC scenarios, WCCs had greater biomass and therefore showed higher nitrate reduction efficiency. In response to FCC scenarios, the performance of less effective WCC practices (e.g., barley, wheat, and late planting) under the baseline indicated ~ 14 % higher increase rate of nitrate reduction efficiency compared to ones with better effectiveness under the baseline (e.g., rye and early planting), due to warmer temperatures. According to simulation results, WCCs were effective to mitigate nitrate loads accelerated by FCCs and therefore the role of WCCs in mitigating nitrate loads is even more important in the given FCCs.

Chesapeake Bay↗
USGS2011

Geophysical data collected from the St. Clair River between Michigan and Ontario, Canada (2008-016-FA)

In 2008, the U.S. Geological Survey (USGS), Woods Hole Coastal and Marine Science Center (WHCMSC), in cooperation with the U.S. Army Corps of Engineers conducted a geophysical and sampling survey of the riverbed of the Upper St. Clair River between Port Huron, Mich., and Sarnia, Ontario, Canada. The objectives were to define the Quaternary geologic framework of the riverbed of the St. Clair River to evaluate the relationship between morphologic change of the riverbed and underlying stratigraphy. This report presents the geophysical and sample data collected from the St. Clair River, May 29-June 6, 2008, as part of the International Upper Great Lakes Study, a 5-year project funded by the International Joint Commission of the United States and Canada to examine whether physical changes in the St. Clair River are affecting water levels within upper Great Lakes, to assess regulation plans for outflows from Lake Superior, and to examine the potential effect of climate change on the Great Lakes water levels (http://www.iugls.org). This document makes available the data that were used in a separate report, U.S. Geological Survey Open-File Report 2009-1137, which detailed the interpretations of the Quaternary geologic framework of the region. This report includes a description of the high-resolution acoustic and sediment-sampling systems that were used to map the morphology, surficial sediment distribution, and underlying geology of the Upper St. Clair River during USGS field activity 2008-016-FA (http://quashnet.er.usgs.gov/cgi-bin/datasource/public_ds_info.pl?fa=2008-016-FA). Video and photographs of the riverbed were also collected and are included in this data release. Future analyses will be focused on substrate erosion and its effects on river-channel morphology and geometry. Ultimately, the International Upper Great Lakes Study will attempt to determine where physical changes in the St. Clair River affect water flow and, subsequently, water levels in the Upper Great Lakes.

Open-File Report↗
USGS1996

Seasonal fluctuations of water quality in San Francisco Bay during the first three years of the regional monitoring program, 1993-1995

The 1995 Regional Monitoring Program (RMP) Annual Report includes monitoring results from the Base Program, Pilot and Special Studies, and summary and perspective articles contributed by RMP investigators and other scientists. The purpose of the RMP is to provide information on the status and trends of contamination in San Francisco Estuary water, sediment, and bivalve tissue, and to assess the potential for biological effects from exposure to those contaminants. The objectives, background, and rationale for the RMP are described in the Introduction (Chapter 1). The 1995 RMP Base Program was essentially the same as in 1994. Water monitoring was conducted in February, April, and August at 24 stations throughout the Estuary. Aquatic bioassays were conducted in February and August at 13 of those stations. Sediment monitoring was conducted in February and August at all 24 stations, and sediment bioassays were conducted at 12 of those stations. Bioaccumulation of contaminants by transplanted bivalves was monitored at 15 stations during two 90 day sampling periods: January to April and July to September. Pilot Studies on benthic fauna and tidal wetlands were conducted and Special Studies on trends in trace elements and development of sediment indicators were also included.

California↗
USGS2022

Characterization of water quality, biology, and habitat of the Pearl River and selected tributaries contiguous to and within Tribal lands of the Pearl River Community of the Mississippi Band of Choctaw Indians, 2017–18

The U.S. Geological Survey, in cooperation with the Mississippi Band of Choctaw Indians (MBCI), conducted a baseline assessment of the physical, chemical, and biological quality of selected streams and rivers within and contiguous to the Pearl River Community (PRC) in 2017 and 2018. The MBCI is a federally recognized tribe with territories in Mississippi and Tennessee. MBCI Tribal government and communities have sovereign authority over their natural resources and are responsible for protecting the quality of waters within the Tribal lands from sources of pollution and restoring impaired waters. The quality of these surface waters has a profound effect upon the health and welfare of MBCI Tribal members. Data generated from this study may be used with other relevant water-quality data for comparison and development of Tribal water-quality standards. The PRC territory is drained by the Pearl River and associated tributaries. Water-quality and biological samples were collected and habitat surveys were conducted at sites on the mainstem of the Pearl River and major tributaries of the Pearl River—Wolf Creek, Beasha Creek, Jones Creek, and Kentawka Creek. The selected stream sites represent a range of land use/land cover and potential sources of alteration and contamination from within their respective drainage areas. In particular, Wolf Creek watershed has the highest relative percentage of developed land. Ambient physicochemical properties, major ions, nutrients, and organic wastewater compounds (OWCs) were analyzed quarterly from surface-water samples from October 2017 through August 2018. Physicochemical properties were also measured in June 2018 over a continuous 48-hour period. Trace elements and polycyclic aromatic hydrocarbons were analyzed from streambed sediments in August 2018. Biological samples included the collection of periphyton algae (August 2018), benthic macroinvertebrate (March 2017 and March 2018), and fish communities (April 2018). Physical stream habitat characteristics were assessed using qualitative (March 2017 and March 2018) and quantitative surveys (August 2018). While not directly applicable, the State of Mississippi Water Quality Standards were used as reference to evaluate Tribal water quality. Physicochemical water-quality constituents—water temperature, specific conductance (SC), pH, and dissolved oxygen (DO)—were generally within natural ranges among sites and samples, with a few exceptions that exceeded existing Mississippi water-quality standards. pH and DO periodically were below the minimum State standards at some sampled sites. Specific conductance was also relatively high at both Wolf Creek sites but did not exceed the existing maximum standard for recreational waters. The surface water among stream sites was predominantly calcium bicarbonate type, with a shift toward sodium-bicarbonate water type at the downstream Wolf Creek (Wolf DS) site. Major ion concentrations were generally highest at the Wolf Creek sites. Nutrient concentrations were also often highest at Wolf DS, but total nitrogen and total phosphorus periodically exceeded recommended State and Federal nutrient criteria thresholds among most sampled sites. Twenty-nine OWCs, including 10 known or suspected endocrine disruptors, were detected among sites. Concentrations of OWCs were relatively low, and only 19 percent of all detections were above the reporting level. Concentrations of copper and nickel in streambed sediments were detected above consensus-based threshold-effect concentrations (TECs) at one site each, and arsenic and chromium exceeded TECs at most sites. Concentrations of all polycyclic aromatic hydrocarbons in streambed sediments were low and well below TECs at all sites. The periphyton, macroinvertebrate, and fish communities at most sampled sites appear typical of central Mississippi streams; however, the diversity, composition, and abundance of taxa sampled from Wolf DS were particularly distinctive compared to other sampled stream sites. Periphyton taxa richness was low at both Wolf Creek sites, and both sites had greater abundances of diatom taxa, which are indicative of high nutrient concentrations, than of soft-algae taxa. Similarly, Wolf DS had relatively low macroinvertebrate diversity, the fewest Ephemeroptera, Plecoptera, and Trichoptera taxa, a high abundance of Tubificid taxa, and the lowest overall Mississippi-Benthic Index of Stream Quality score. Fish species richness was also relatively low at Wolf DS compared to some other sampled sites. Habitat characteristics also appeared to be generally typical of most central Mississippi streams. Qualitative habitat assessment scores were at or above the regional least disturbed streams for Wolf DS, the upstream Wolf Creek (Wolf US) site, and Jones Creek. Habitat scores among the remaining sites indicate fair conditions. Quantitative and qualitative habitat characteristics indicate relatively lower habitat quality at the two Beasha Creek sites.

Mississippi↗
USGS2000

Data for Quaternary faults, liquefaction features, and possible tectonic features in the Central and Eastern United States, east of the Rocky Mountain Front

The USGS is currently leading an effort to compile published geological information on Quaternary faults, folds, and earthquake-induced liquefaction in order to develop an internally consistent database on the locations, ages, and activity rates of major earthquake-related features throughout the United States. This report is the compilation for such features in the Central and Eastern United States (CEUS), which for the purposes of the compilation, is defined as the region extending from the Rocky Mountain Front eastward to the Atlantic seaboard. A key objective of this national compilation is to provide a comprehensive database of Quaternary features that might generate strong ground motion and therefore, should be considered in assessing the seismic hazard throughout the country. In addition to printed versions of regional and individual state compilations, the database will be available on the World-Wide Web, where it will be readily available to everyone. The primary purpose of these compilations and the derivative database is to provide a comprehensive, uniform source of geological information that can by used to complement the other types of data that are used in seismic-hazard assessments. Within our CEUS study area, which encompasses more than 60 percent of the continuous U.S., we summarize the geological information on 69 features that are categorized into four classes (Class A, B, C, and D) based on what is known about the feature's Quaternary activity. The CEUS contains only 13 features of tectonic origin for which there is convincing evidence of Quaternary activity (Class A features). Of the remaining 56 features, 11 require further study in order to confidently define their potential as possible sources of earthquake-induced ground motion (Class B), whereas the remaining features either lack convincing geologic evidence of Quaternary tectonic faulting or have been studied carefully enough to determine that they do not pose a significant seismic hazard (Classes C and D). The correlation between historical seismicity and Quaternary faults and liquefaction features in the CEUS is generally poor, which probably reflects the long return times between successive movements on individual structures. Some Quaternary faults and liquefaction features are located in aseismic areas or where historical seismicity is sparse. These relations indicate that the record of historical seismicity does not identify all potential seismic sources in the CEUS. Furthermore, geological studies of some currently aseismic faults have shown that the faults have generated strong earthquakes in the geologically recent past. Thus, the combination of geological information and seismological data can provide better insight into potential earthquake sources and thereby, contribute to better, more comprehensive seismic-hazard assessments.

Open-File Report↗
USGS2015

Engagement with indigenous peoples and honoring traditional knowledge systems

The organizers of the 2014 US National Climate Assessment (NCA) made a concerted effort to reach out to and collaborate with Indigenous peoples, resulting in the most comprehensive information to date on climate change impacts to Indigenous peoples in a US national assessment. Yet, there is still much room for improvement in assessment processes to ensure adequate recognition of Indigenous perspectives and Indigenous knowledge systems. This article discusses the process used in creating the Indigenous Peoples, Land, and Resources NCA chapter by a team comprised of tribal members, agencies, academics, and non-governmental organizations, who worked together to solicit, collect, and synthesize traditional knowledges and data from a diverse array of Indigenous communities across the US. It also discusses the synergy and discord between traditional knowledge systems and science and the emergence of cross-cutting issues and vulnerabilities for Indigenous peoples. The challenges of coalescing information about climate change and its impacts on Indigenous communities are outlined along with recommendations on the types of information to include in future assessment outputs. We recommend that future assessments – not only NCA, but other relevant local, regional, national, and international efforts aimed at the translation of climate information and assessments into meaningful actions – should support integration of Indigenous perspectives in a sustained way that builds respectful relationships and effectively engages Indigenous communities. Given the large number of tribes in the US and the current challenges and unique vulnerabilities of Indigenous communities, a special report focusing solely on climate change and Indigenous peoples is warranted. This article is part of a special issue on “The National Climate Assessment: Innovations in Science and Engagement” edited by Katharine Jacobs, Susanne Moser, and James Buizer.

Climatic Change↗
USGS2014

Estimate of undiscovered copper resources of the world, 2013

Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 3,500 million metric tons (Mt) of undiscovered copper among 225 tracts around the world. Annual U.S. copper consumption is 2 Mt; global consumption is 20 Mt. The USGS assessed undiscovered copper in two deposit types that account for about 80 percent of the world's copper supply. Results of the assessment are provided by deposit type for 11 regions. Approximately 50 percent of the global total occurs in South America, South Central Asia and Indochina, and North America combined.

Fact Sheet↗
USGS2001

Selected ground-water data for Yucca Mountain region, southern Nevada and eastern California, through December 1999

The U.S. Geological Survey, in support of the U.S. Department of Energy, Yucca Mountain Site Characterization Project, collects, compiles, and summarizes hydrologic data in the Yucca Mountain region. The data are collected to allow assessments of ground-water resources during studies to determine the potential suitability of Yucca Mountain for storing high-level nuclear waste. Data on ground-water levels at 34 wells and a fissure (Devils Hole), ground-water discharge at 5 springs and a flowing well, and total reported ground-water withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert are presented for calendar year 1999. Data collected prior to 1999 are graphically presented and data collected by other agencies (or as part of other Geological Survey programs) are included to further indicate variations of ground-water levels, discharges, and withdrawals through time. A statistical summary of ground-water levels at seven wells in Jackass Flats is presented to indicate potential effects of ground-water withdrawals associated with U.S. Department of Energy activities near Yucca Mountain. The statistical summary includes the number of measurements, the maximum, minimum, and median water-level altitudes, and the average deviation of measured water-level altitudes for selected baseline periods and for calendar years 1992-99. At two water-supply wells median water levels for calendar year 1999 were unchanged from their respective baseline periods. At a nearby observation well, the 1999 median water level was slightly lower (0.1 foot) than its baseline period. At the remaining four wells in Jackass Flats, median water levels for 1999 were slightly higher (0.2 foot to 1.6 feet) than for their respective baseline periods.

Open-File Report↗
USGS2018

Assessment of oil and gas resources in the Upper Jurassic Haynesville and Bossier Formations, U.S. Gulf Coast, 2016

The U.S. Geological Survey completed a geology-based assessment of undiscovered, technically recoverable oil and gas resources in the Haynesville and Bossier Formations of the onshore and State waters portion of the U.S. Gulf Coast region. Haynesville Formation conventional oil and gas production began in the late 1930s, whereas Bossier Formation production began in the early 1970s. Production of continuous gas resources from both formations began in 2006–7. Most of the current activity is focused on natural gas production from Haynesville and Bossier shales using horizontal wells and hydraulic fracturing. In 2016, t he U.S. Geological Survey assessed technically recoverable mean resources of 4 billion barrels of oil and 304.4 trillion cubic feet of gas in the Haynesville and Bossier Formations of the onshore and State waters portion of the U.S. Gulf Coast region.

Open-File Report↗
USGS1998

Database of significant deposits of gold, silver, copper, lead, and zinc in the United States

It has long been recognized that the largest mineral deposits contain most of the known mineral endowment (Singer and DeYoung, 1980). Sometimes called giant or world-class deposits, these largest deposits account for a very large share of historic and current mineral production and resources in industrial society (Singer, 1995). For example, Singer (1995) shows that the largest 10 percent of the world’s gold deposits contain 86 percent of the gold discovered to date. Many mineral resource issues and investigations are more easily addressed if limited to the relatively small number of deposits that contain most of the known mineral resources. An estimate of known resources using just these deposits would normally be sufficient, because considering smaller deposits would not add significantly to the total estimate. Land-use planning should treat mainly with these deposits due to their relative scarcity, the large share of known resources they contain, and the fact that economies of scale allow minerals to be produced much more cheaply from larger deposits. Investigation of environmental and other hazards that result from mining operations can be limited to these largest deposits because they account for most of past and current production. The National Mineral Resource Assessment project of the U.S. Geological Survey (USGS) has compiled a database on the largest known deposits of gold, silver, copper, lead, and zinc in the United States to complement the 1996 national assessment of undiscovered deposits of these same metals (Ludington and Cox, 1996). The deposits in this database account for approximately 99 percent of domestic production of these metals and probably a similar share of identified resources. These data may be compared with results of the assessment of undiscovered resources to characterize the nation’s total mineral endowment for these metals. This database is a starting point for any national or regional mineral-resource or mineral-environmental investigation.

Open-File Report↗
USGS2001

Selected ground-water data for Yucca Mountain region, southern Nevada and eastern California, through December 1998

The U.S. Geological Survey, in support of the U.S. Department of Energy, Yucca Mountain Site Characterization Project, collects, compiles, and summarizes hydrologic data in the Yucca Mountain region. The data are collected to allow assessments of ground-water resources during studies to determine the potential suitability of Yucca Mountain for storing high-level nuclear waste. Data on ground-water levels at 34 wells and a fissure (Devils Hole), ground-water discharge at 5 springs and a flowing well, and total reported ground-water withdrawals within Crater Flat, Jackass Flats, Mercury Valley, and the Amargosa Desert are presented for calendar year 1998. Data collected prior to 1998 are graphically presented and data collected by other agencies (or as part of other Geolgical Survey programs) are included to further indicate variations of ground-water levels, discharges, and withdrawals through time. A statistical summary of ground-water levels at seven wells in Jackass Flats is presented to indicate potential effects of ground-water withdrawals associated with U.S. Department of Energy activities near Yucca Mountain. The statistical summary includes the number of measurements, the maximum, minimum, and median water-level altitudes, and the average deviation of measured water-level altitudes for selected baseline periods and for calendar years 1992-98. At two water-supply wells and a nearby observation well, median water levels for calendar year 1998 were slightly lower (0.2 to 0.3 foot) than for their respective baseline periods. At the remaining four wells in Jackass Flats, median water levels for 1998 were unchanged at two wells and slightly higher (0.4 and 1.4 foot) at two wells than those for their respective baseline periods.

Open-File Report↗
USGS2002

Quality of shallow ground water in areas of recent residential and commercial development, Wichita, Kansas, 2000

Water samples from 30 randomly distributed monitoring wells in areas of recent residential and commercial development (1960–96), Wichita, Kansas, were collected in 2000 as part of the High Plains Regional Ground-Water Study conducted by the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. The samples were analyzed for about 170 water-quality constituents that included chlorofluorocarbons, physical properties, dissolved solids and major ions, nutrients and dissolved organic carbon, trace elements, pesticide compounds, and volatile organic compounds. The purpose of this report is to provide an assessment of water quality in recharge to shallow ground water underlying areas of recent residential and commercial development and to determine the relation of ground-water quality to overlying urban land use. Analyses of water from the 30 monitoring wells for chlorofluorocarbons were used to estimate apparent dates of recharge. Water from 18 wells with nondegraded and uncontaminated chlorofluorocarbon concentrations had calculated apparent recharge dates that ranged from 1979 to 1990 with an average date of 1986. Water from 14 monitoring wells (47 percent) exceeded the 500-milligrams-per-liter Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency for dissolved solids in drinking water. The Secondary Maximum Contaminant Levels of 250 milligrams per liter for chloride and sulfate were exceeded in water from one well. The source of the largest concentrations of dissolved solids and associated ions, such as chloride and sulfate, in shallow ground water in the study area probably is highly mineralized water moving out of the Arkansas River into the adjacent, unconsolidated deposits and mixing with the dominant calcium bicarbonate water in the deposits. Concentrations of most nutrients in water from the sampled wells were small, with the exception of nitrate. Although water from the sampled wells did not have nitrate concentrations larger than the 10-milligram-per-liter Maximum Contaminant Level for drinking water, water from 50 percent of the sampled wells showed nitrate enrichment (concentrations greater than 2.0 milligrams per liter). Most trace elements in water from the sampled wells were detected only in small concentrations, and few exceeded respective water-quality standards. Twenty percent of iron concentrations, 40 percent of manganese concentrations, 3 percent of arsenic concentrations, and 13 percent of uranium concentrations exceeded respective Maximum Contaminant Levels or Secondary Maximum Contaminant Levels. A total of 47 pesticide compounds were analyzed in ground-water samples during this study. Water from 73 percent of the wells sampled had detectable concentrations of one or more of 8 of these 47 compounds. The herbicide atrazine or its degradation product deethylatrazine were detected most frequently (in water from 70 percent of the sampled wells). Metolachlor was detected in water from 10 percent of the wells, and simazine was detected in water from 30 percent of the wells sampled. Other pesticides detected included dieldrin, pendimethalin, prometon, and tebuthiuron (each in water from 3 percent of the wells). All concentrations of these compounds were less than established Maximum Contaminant Levels. A total of 85 volatile organic compounds (VOCs) were analyzed in ground-water samples during this study. Water from 43 percent of the wells had a detectable concentration of one or more VOCs. Chloroform was the most frequently detected VOC (23 percent of the wells sampled).Seven other VOCs were detected in water at frequencies of 13 percent or less in the wells sampled. Concentrations of VOCs were less than respective Maximum Contaminant Levels, except one sample with a concentration of 9.0 micrograms per liter for tetrachloroethylene (Maximum Contaminant Level of 5.0 micrograms per liter). An analysis of hydraulic gradient, flow velocity, and residence time of the ground water indicated potential recharge areas that ranged from 0.8 to 2.8 miles upgradient of monitoring-well locations. Nineteen (63 percent) of these potential recharge areas were in agricultural areas or areas in transition from agricultural to residential and (or) commercial land use at the time water sampled from the monitoring wells was recharged to the shallow ground water. The occurrence of atrazine or deethylatrazine in water from 70 percent of the monitoring wells may indicate a historical agricultural land-use relation. This agricultural relation also may affect concentrations of other water-quality constituents of possible agricultural origin such as nitrate, which generally were in excess of background concentrations in shallow ground water.

Kansas↗
USGS2005

Regionalized equations for bankfull-discharge and channel characteristics of streams in New York State—Hydrologic Region 6 in the Southern Tier of New York

Equations that relate bankfull discharge and channel characteristics (width, depth, and cross-sectional area) to drainage-area size at gaged sites are needed to define bankfull discharge and channel dimensions at ungaged sites and to provide information for watershed assessments, stream-channel classification, and the design of stream-restoration projects. Such equations are most accurate if derived from streams within an area of uniform hydrologic, climatic, and physiographic conditions and applied only within that region. In New York State, eight hydrologic regions were previously defined on the basis of similar high-flow (flood) characteristics. This report presents drainage areas and associated bankfull characteristics (discharge and channel dimensions) for surveyed streams in southwestern New York (Region 6). Stream-survey data and discharge records from 11 active (currently gaged) sites and 3 inactive (discontinued) sites were used in regression analyses to relate bankfull discharge and bankfull channel width, depth, and cross-sectional area to the size of the drainage area. The resulting equations are: (1) bankfull discharge, in cubic feet per second = 48.0*(drainage area, in square miles) 0.842 ; (2) bankfull channel width, in feet = 16.9*(drainage area, in square miles) 0.419 ; (3) bankfull channel depth, in feet = 1.04*(drainage area, in square miles) 0.244 ; and (4) bankfull channel cross-sectional area, in square feet = 17.6*(drainage area, in square miles) 0.662 . The coefficient of determination (R 2 ) for these four equations were 0.90, 0.79, 0.64, and 0.89, respectively. The high correlation coefficients for bankfull discharge and cross-sectional area indicate that much of the variation in these variables is explained by the size of the drainage area. The smaller correlation coefficients for bankfull channel width and depth indicate that other factors also affect these relations. Recurrence intervals for the estimated bankfull discharge of each stream ranged from 1.01 to 2.35 years; the mean recurrence interval was 1.54 years. The 14 surveyed streams were classified by Rosgen stream type; most were C-type reaches, with occasional B-type reaches. The Region 6 equation (curve) for bankfull discharge was compared with equations previously developed for four other large areas in New York State and southeastern Pennsylvania. The differences among results indicate that, although the equations need to be refined by region before being applied by water-resources managers to local planning and design efforts, similar regions have similar relations between bankfull discharge and channel characteristics.

Scientific Investigations Report↗
USGS2019

Phytoplankton community and algal toxicity at a recurring bloom in Sullivan Bay, Kabetogama Lake, Minnesota, USA

Kabetogama Lake in Voyageurs National Park, Minnesota, USA suffers from recurring late summer algal blooms that often contain toxin-producing cyanobacteria. Previous research identified the toxin microcystin in blooms, but we wanted to better understand how the algal and cyanobacterial community changed throughout an open water season and how changes in community structure were related to toxin production. Therefore, we sampled one recurring bloom location throughout the entire open water season. The uniqueness of this study is the absence of urban and agricultural nutrient sources, the remote location, and the collection of samples before any visible blooms were present. Through quantitative polymerase chain reaction (qPCR), we discovered that toxin-forming cyanobacteria were present before visible blooms and toxins not previously detected in this region (anatoxin-a and saxitoxin) were present, indicating that sampling for additional toxins and sampling earlier in the season may be necessary to assess ecosystems and human health risk.

Minnesota↗