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At least 469 records · Page 26Linked to original sources
USGS2020

Visualizing the ecological importance of pre-Euro-American settlement fire across three Midwestern landscapes

Bearing-tree data were used to calculate an index, pyrophilic percentage, depicting the importance of fire before Euro-American settlement on three landscapes, two within the Prairie Peninsula and one outside the region. Based on functional traits, bearing trees were classified as either pyrophilic or pyrophobic, applied to Public Land Survey points, and the pyrophilic percentage was calculated for each point. Kriging was applied to this point database to create a continuous surface of pyrophilic percentages. Regression analysis was used to relate this surface to environmental factors. Regression models created separately for each study area explained 38 to 53% of the variation in pyrophilic percentage. A positive association between pyrophilic percentage and distance to water and summer potential evapotranspiration was consistent across all study sites. The consistently high values and spatial patterns of pyrophilic percentage revealed fire-dominated landscapes interspersed with patches of pyrophobic vegetation. The restriction of pyrophobic areas to the leeside (east) of waterbodies indicated these served as firebreaks in a fire-swept landscape. Lake Michigan must have had a profound effect on pre- Euro-American settlement fire environments, serving as a massive physical firebreak while casting a moist maritime climate eastward. In southern and southwestern Illinois, the Mississippi River and associated tributaries along with an increase in topographic complexity also served as firebreaks, with pyrophobic forests restricted to riparian zones which progressively graded to pyrophilic vegetation on surrounding uplands. Our analysis expands the use of Public Land Survey data by converting bearing trees into a meaningful fire ecology index. While much of the landscape included in our study area is now in agriculture or urbanized, pyrophilic percentage maps can help guide land managers in the application of fire for restoration, conservation, and forestry purposes.

Illinois, Indiana, Michigan, Wisconsin↗
USGS2024

Site response in the Walnut Creek–Concord region of the San Francisco Bay, California: Ground motion amplification in a fault-bounded basin

Thirty‐seven portable accelerometers were deployed in the eastern San Francisco Bay communities of Walnut Creek and Concord to study site response in a fault‐bounded, urban, sedimentary basin. Local earthquakes were recorded for a period of two years from 2017 to 2019 resulting in 101 well‐recorded events. Site response is estimated by two methods: the reference site spectral ratio method and a source‐site spectral inversion method. The reference site spectral ratio method allows investigation of the variability of site amplification with source azimuth and frequency. The source‐site spectral inversion method yields the best least‐squares fit to site response for a database of ground‐motion records. Both methods show substantial amplification in the Walnut Creek–Concord basin below 2 Hz indicating strong surface‐wave development. Greater amplification is seen for sources aligned along the long axis of the basin. Inversion using close‐in sources at short distances yields lower amplification at longer periods than the entire data set due to reduced surface‐wave generation for steeper angles of incidence. Inversion of site response spectra for shallow shear‐wave velocity using a global search algorithm yields V S30 values consistent with generalized mapping results based on geology and topography but with greater variability due to local site variations. 3D finite‐element modeling shows greater amplification in the Walnut Creek–Concord basin with a basin‐edge effect likely contributing to higher ground motions. Topography is also seen to lead to increased scattering and shadowing effects.

California↗
USGS2003

Land use and land cover change in the Greater Yellowstone Ecosystem: 1975-1995

Shifts in the demographic and economic character of the Greater Yellowstone Ecosystem (GYE) are driving patterns of land cover and land use change in the region. Such changes may have important consequences for ecosystem functioning. The objective of this paper is to quantify the trajectories and rates of change in land cover and use across the GYE for the period 1975-1995 using satellite imagery. Spectral and geographic variables were used as inputs to classification tree regression analysis (CART) to find "rules" which defined land use and land cover classes on the landscape. The resulting CART functions were used to map land cover and land use across seven Landsat TM scenes for 1995. We then used a thresholding technique to identify locations that differed in spectral properties between the 1995 and 1985 time periods. These "changed" locations were classified using CART functions derived from spectral and geographic data from 1985. This was similarly done for the year 1975 based on Landsat MSS data. Differences between the 1975, 1985, and 1995 maps were considered change in land cover and use. We calibrated and tested the accuracy of our models using data acquired through manual interpretation of aerial photos. Elevation and vegetative indices derived from the remotely sensed satellite imagery explained the most variance in the land use and land cover classes (-i.e., defined the "rules" most often). Overall accuracies from our study were good, ranging from 94% at the coarsest level of detail to 74% at the finest. The largest changes over the study period were the increases in burned, urban, and mixed conifer-herbaceous classes and decreases in woody deciduous, mixed woody deciduous-herbaceous, and conifer habitats. These changes have important implications for ecological function and biodiversity. The expansion of mixed conifer classes may increase fuel loads and enhance risk to the growing number of rural homes. The reduction of woody deciduous cover types is likely reducing population sizes for the numerous plant and animal species that specialize on this habitat type. Some of these species are also negatively influenced by the increase of rural homes in and near woody deciduous habitats.

Idaho, Montana, Wyoming↗
USGS2016

Nutrient, organic carbon, and chloride concentrations and loads in selected Long Island Sound tributaries—Four decades of change following the passage of the Federal Clean Water Act

Trends in long-term water-quality and streamflow data from 14 water-quality monitoring sites in Connecticut were evaluated for water years 1974–2013 and 2001–13, coinciding with implementation of the Clean Water Act of 1972 and the Connecticut Nitrogen Credit Exchange program, as part of an assessment of nutrient and chloride concentrations and loads discharged to Long Island Sound. In this study, conducted by the U.S. Geological Survey in cooperation with the Connecticut Department of Energy and Environmental Protection, data were evaluated using a recently developed methodology of weighted regressions with time, streamflow, and season. Trends in streamflow were evaluated using a locally weighted scatterplot smoothing method. Annual mean streamflow increased at 12 of the 14 sites averaging 8 percent during the entire study period, primarily in the summer months, and increased by an average of 9 percent in water years 2001–13, primarily during summer and fall months. Downward trends in flow-normalized nutrient concentrations and loads were observed during both periods for most sites for total nitrogen, total Kjeldahl nitrogen, nitrite plus nitrate nitrogen, total phosphorus, and total organic carbon. Average flow-normalized loads of total nitrogen decreased by 23.9 percent for the entire period and 10.9 percent for the period of water years 2001‒13. Major factors contributing to decreases in flow-normalized loads and concentrations of these nutrients include improvements in wastewater treatment practices, declining atmospheric wet deposition of nitrogen, and changes in land management and land use. Loads of dissolved silica (DSi; flow-normalized and non-flow-normalized) increased slightly at most stations during the study period and were positively correlated to urbanized land in the basin and negatively correlated to area of open water. Concentrations and loads of chloride increased at 12 of the 14 sites during both periods. Increases likely are the result of an increase in the use of salt for deicing, as well as other factors related to urbanization and population growth, such as increases in wastewater discharge and discharge from septic systems.

Connecticut↗
USGS2005

Assessment of shallow ground-water quality in recently urbanized areas of Sacramento, California, 1998

Evidence for anthropogenic impact on shallow ground-water quality beneath recently developed urban areas of Sacramento, California, has been observed in the sampling results from 19 monitoring wells in 1998. Eight volatile organic compounds (VOCs), four pesticides, and one pesticide transformation product were detected in low concentrations, and nitrate, as nitrogen, was detected in elevated concentrations; all of these concentrations were below National and State primary and secondary maximum contaminant levels. VOC results from this study are more consistent with the results from urban areas nationwide than from agricultural areas in the Central Valley, indicating that shallow ground-water quality has been impacted by urbanization. VOCs detected may be attributed to either the chlorination of drinking water, such as trichloromethane (chloroform) detected in 16 samples, or to the use of gasoline additives, such as methyl tert-butyl ether (MTBE), detected in 2 samples. Pesticides detected may be attributed to use on household lawns and gardens and rights-of-way, such as atrazine detected in three samples, or to past agricultural practices, and potentially to ground-water/surface-water interactions, such as bentazon detected in one sample from a well adjacent to the Sacramento River and downstream from where bentazon historically was used on rice. Concentrations of nitrate may be attributed to natural sources, animal waste, old septic tanks, and fertilizers used on lawns and gardens or previously used on agricultural crops. Seven sample concentrations of nitrate, as nitrogen, exceeded 3.0 milligrams per liter, a level that may indicate impact from human activities. Ground-water recharge from rainfall or surface-water runoff also may contribute to the concentrations of VOCs and pesticides observed in ground water. Most VOCs and pesticides detected in ground-water samples also were detected in air and surface-water samples collected at sites within or adjacent to the recently developed urban areas. Five arsenic sample concentrations exceeded the U.S. Environmental Protection Agency (USEPA) primary maximum contaminant level (MCL) of 10 milligrams per liter adopted in 2001. Measurements that exceeded USEPA or California Department of Health Services recommended secondary maximum contaminant levels include manganese, iron, chloride, total dissolved solids, and specific conductance. These exceedances are probably a result of natural processes. Variations in stable isotope ratios of hydrogen (2H/1H) and oxygen (18O/16O) may indicate different sources or a mixing of recharge waters to the urban ground water. These variations also may indicate recharge directly from surface water in one well adjacent to the Sacramento River. Tritium concentrations indicate that most shallow ground water has been recharged since the mid-1950s, and tritium/helium-3 age dates suggest that recharge has occurred in the last 2 to 30 years in some areas. In areas where water table depths exceed 20 meters and wells are deeper, ground-water recharge may have occurred prior to 1950, but low concentrations of pesticides and VOCs detected in these deeper wells indicate a mixing of younger and older waters. Overall, the recently urbanized areas can be divided into two groups. One group contains wells where few VOCs and pesticides were detected, nitrate mostly was not detected, and National and State maximum contaminant levels, including the USEPA MCL for arsenic, were exceeded; these wells are adjacent to rivers and generally are characterized by younger water, shallow (1 to 4 meters) water table, chemically reducing conditions, finer grained sediments, and higher organics in the soils. In contrast, the other group contains wells where more VOCs, pesticides, and elevated nitrate concentrations were detected; these wells are farther from rivers and are generally characterized by a mixture of young and old waters, intermediate to deep (7 to 35 meters) wate

Scientific Investigations Report↗
USGS1996

Trends in surface-water quality in Connecticut, 1969-88

Surface-water-quality data from selected monitoring stations in Connecticut were analyzed for trend, using the Seasonal Kendall test, for water years 1969-88, 1975-88, and 1981-88. The number of constituents and stations evaluated varied with the different time periods. The 39 monitoring stations included 26 freshwater streams with associated discharge data, 7 tidally affected streams, 4 harbor stations, and 2 surface impoundments. Flow-adjustment procedures were used where possible to minimize the effects of stream- flow variability on trend results. The drainage area of the monitoring stations includes approximately 5,000 mi 2 covering the State of Connecticut and about 11,000 mi 2 in upstream drainage areas outside of the State. Drainage basin size for the freshwater streams ranges from 4.1 mi 2 to 9,660 mi 2 . Land uses in the drainage basins range from undeveloped forested areas to highly urbanized metropolitan areas. During the period covered by the trend study, the State's population has grown, suburban development has increased, agricultural land use has decreased, and wastewater-treatment practices have improved. Increases in specific conductance and in the concentrations of calcium, magnesium, chloride, sulfate, dissolved solids, and total solids were geographically widespread and numerous during water years 1975-88 and indicate a general increase statewide in dissolved constituents in streamflow, both in urbanized and less developed areas. The effects of increasing urbanization, including municipal and industrial wastewater, septic system leachate, nonpoint runoff, and atmospheric deposition of contaminants, are possible causes for these increases. Decreases in turbidity and in the concentrations of total phosphorus, total organic carbon, and fecal coliform bacteria were geographically widespread and numerous during 1975-88. This general decrease in suspended material and bacteria may be attributable to basic improvements in the treatment of municipal and industrial wastewater during the period of record. Decreasing concentrations of total phosphorus may also be related to decreases in agricultural land use and to a decline in the use of detergents containing phosphorus. Detected decreases in total organic carbon and turbidity may have been caused, in part, by changes in sampling or analytical methods. Increases in total nitrogen, total organic nitrogen, and total nitrite-plus- nitrate were geographically widespread and numerous during 1975-88 and appear to indicate effects from both point sources in urbanized basins and nonpoint sources in less developed basins. The number of stations with increasing concentrations of nitrogen constituents was much smaller during 1981-88 than during 1975-88. Decreases in total ammonia nitrogen were detected at 11 stations during 1981-88. Decreases in total ammonia, sometimes paired with increases in total nitrite-plus-nitrate, may result from improvements in wastewater treatment. Increases in the concentration of dissolved oxygen, or dissolved oxygen as a percent of saturation, were geographically widespread and numerous during 1969-88 and 1975-88. Increases were less common during 1981-88. Increases in dissolved oxygen in urbanized basins may be related to major improvements in wastewater treatment during the 1970's and 1980's. The magnitude of the trends detected during 1969-88 may have been affected in part by a change, around 1974, in the model of the instrument used to measure dissolved oxygen in the field. Statewide increases in pH were detected during 1969-88, 1975-88, and 1981-88, in both urbanized and less developed basins. The widespread increases in pH were unexpected, given the relatively acidic quality of precipitation in the region during the study period. Only two decreases in pH were detected, both in relatively undeveloped basins. Increases in pH in urbanized areas may be related to decreasing concentrations of ammonia and to requirements for neutralization of municipal and industrial wastewater.

Connecticut↗
USGS1997

Water-quality assessment of the Las Vegas Valley area and the Carson and Truckee River basins, Nevada and California: Nutrients, pesticides, and suspended sediment, October 1969-April 1990

The U.S. Geological Survey National Water-Quality Assessment Program (NAWQA) is designed to provide long-term, consistent information on water quality that can be used to describe local, regional, and national conditions. The full-scale NAWQA Program, initiated in 1991, includes both study-unit and national synthesis activities. Study-unit investigations provide scientific data and interpretations that will be integrated by national synthesis studies to assess the quality of the Nation's water resources. The Nevada Basin and Range (NVBR) study unit is one of 60 proposed NAWQA study units in the United States. These riverbasin-scale areas were selected to represent large proportions of the Nation's water use and population served by public supplies, and the Nation's geographic diversity. The NVBR study unit includes the Las Vegas Valley area, approximately 1,640 mi in southern Nevada, and the Carson River Basin (3,970 mi 2 ) and Truckee River Basin (3,230 mi 2 ) in northwestern Nevada and northeastern California. The areas are typical of Basin and Range physiography. Snowfall in high mountains provides streamflow and ground-water recharge in adjacent basins. Unconsolidated basin-fill deposits commonly exceed 1,000 ft in thickness and are principal aquifers in the study unit. The study-unit climate varies from humid continental in the Sierra Nevada where the Carson and Truckee Rivers originate (annual precipitation exceeds 30 in.) to desert in terminal parts of the basins, including the Carson Desert and lower altitudes in Las Vegas Valley, where annual precipitation is less than 5 in. In 1990, Nevada had the greatest population growth rate and the fourth greatest percentage of population residing in urban areas in the Nation. More than 90 percent of Nevada's population (about 1,090,000 in 1990) resided in the study unit; the Las Vegas Valley area (about 710,000) was the most populous area. In 1990, water use in the study unit was about 1,117,000 acre-ft. Water use in the Las Vegas Valley area was about 317,000 acre-ft; 91 percent was for public supplies. Las Vegas Valley was 79 percent range land, but the 5 percent urban land use has significantly affected water resources. Water use in the Carson River Basin was 538,000 acre-ft in 1990. About 95 percent of the water was used for irrigation, although only 5 percent of the land was used for irrigated agriculture. Water use in the Truckee River Basin was 262,000 acre-ft in 1990. Public supply used about 36 percent of the water, although only 3 percent of the land was urban. Nutrients, pesticides, and suspended sediments are important water-quality issues in the study unit. Urban runoff and treated sewage effluent contribute these constituents to Las Vegas Wash and the Truckee River. Urban and agricultural activities in the Carson and Truckee River Basins are also sources of these constituents.

California, Nevada↗
USGS2010

Mercury and methylmercury dynamics in a coastal plain watershed, New Jersey, USA

The upper Great Egg Harbor River watershed in New Jersey's Coastal Plain is urbanized but extensive freshwater wetlands are present downstream. In 2006-2007, studies to assess levels of total mercury (THg) found concentrations in unfiltered streamwater to range as high as 187 ng/L in urbanized areas. THg concentrations were <20 ng/L in streamwater in forested/wetlands areas where both THg and dissolved organic carbon concentrations tended to increase while pH and concentrations of dissolved oxygen and nitrate decreased with flushing of soils after rain. Most of the river's flow comes from groundwater seepage; unfiltered groundwater samples contained up to 177 ng/L of THg in urban areas where there is a history of well water with THg that exceeds the drinking water standard (2,000 ng/L). THg concentrations were lower (<25 ng/L) in unfiltered groundwater from downstream wetland areas. In addition to higher THg concentrations (mostly particulate), concentrations of chloride were higher in streamwater and groundwater from urban areas than in those from downstream wetland areas. Methylmercury (MeHg) concentrations in unfiltered streamwater ranged from 0.17 ng/L at a forest/wetlands site to 2.94 ng/L at an urban site. The percentage of THg present as MeHg increased as the percentage of forest + wetlands increased, but also was high in some urban areas. MeHg was detected only in groundwater <1 m below the water/sediment interface. Atmospheric deposition is presumed to be the main source of Hg to the wetlands and also may be a source to groundwater, where wastewater inputs in urban areas are hypothesized to mobilize Hg deposited to soils. ?? 2010 US Government.

Water, Air, & Soil Pollution↗
USGS2022

Urban proximity while breeding is not a predictor of perfluoroalkyl substance contamination in the eggs of brown pelicans

Identifying sources of exposure to chemical stressors is difficult when both target organisms and stressors are highly mobile. While previous studies have demonstrated that populations of some organisms proximal to urban centers may display increased burdens of human-created chemicals compared to more distal populations, this relationship may not be universal when applied to organisms and stressors capable of transboundary movements. We examined eggs of brown pelicans ( Pelecanus occidentalis ), a nearshore seabird with daily movements ranging from local to 50 km and annual migrations ranging from year-round residency to 1500 km. Thirty-six eggs from three breeding colonies located at increasing distances to a major urban center (Charleston, South Carolina, USA) were analyzed for concentrations of per - and polyfluoroalkyl substances (PFAS). Areas of high use for each colony during the breeding season were also assessed via the tracking of adult pelicans from each colony using GPS-PTT satellite transmitters and overlapped with measures of relative urbanization via land cover data. We report potentially significant ∑PFAS concentrations in the eggs of pelicans (175.4 ± 120.1 ng/g w wt. SD), driven largely by linear perfluorooctane sulfonate (n-PFOS) (48–546 ng/g w wt.). Residues of the precursor compound perfluorooctane sulfonamide (FOSA) were also present in pelican eggs, suggesting continued exposure of local wildlife beyond implemented phaseouts of some PFAS. For most analytes, egg concentrations did not exhibit a significant spatial structure despite some differentiation in high-use areas unlike similar data for another regional apex predator, the bottlenose dolphin ( Tursiops truncatus ). We suggest that the partially migratory nature of brown pelicans during the non-breeding season, combined with daily ranges that may extend to 50 km from local point sources, may have homogenized exposure across individuals. Charleston likely remains a major source for PFAS in the overall region, however, given the high concentrations observed as well as known releases of PFAS in the nearshore environment.

South Carolina↗
USGS2021

Developing climate resilience in aridlands using rock detention structures as green infrastructure

The potential of ecological restoration and green infrastructure has been long suggested in the literature as adaptation strategies for a changing climate, with an emphasis on revegetation and, more recently, carbon sequestration and stormwater management. Tree planting and “natural” stormwater detention structures such as bioswales, stormwater detention basins, and sediment traps are popular approaches. However, the experimental verification of performance for these investments is scarce and does not address rock detention structures specifically. This 3-year study investigates the infiltration, peak flow mitigation, and microclimate performance of a natural wash stormwater retention installation using one-rock dams in an urban park in Phoenix, Arizona, USA. Field data collected during the study do not depict change in the hydrogeomorphology. However, hydrologic modeling, using data collected from the field, portrays decreases in peak flows and increases in infiltration at the treated sites. Additionally, we observe a lengthening of microclimate cooling effects following rainfall events, as compared with the untreated sites. In this urban arid land setting, the prospect that rock detention structures themselves could reduce warming or heat effects is promising.

Arizona↗
USGS2017

Stormwater management network effectiveness and implications for urban watershed function: A critical review

Deleterious effects of urban stormwater are widely recognized. In several countries, regulations have been put into place to improve the conditions of receiving water bodies, but planning and engineering of stormwater control is typically carried out at smaller scales. Quantifying cumulative effectiveness of many stormwater control measures on a watershed scale is critical to understanding how small-scale practices translate to urban river health. We review 100 empirical and modelling studies of stormwater management effectiveness at the watershed scale in diverse physiographic settings. Effects of networks with stormwater control measures (SCMs) that promote infiltration and harvest have been more intensively studied than have detention-based SCM networks. Studies of peak flows and flow volumes are common, whereas baseflow, groundwater recharge, and evapotranspiration have received comparatively little attention. Export of nutrients and suspended sediments have been the primary water quality focus in the United States, whereas metals, particularly those associated with sediments, have received greater attention in Europe and Australia. Often, quantifying cumulative effects of stormwater management is complicated by needing to separate its signal from the signal of urbanization itself, innate watershed characteristics that lead to a range of hydrologic and water quality responses, and the varying functions of multiple types of SCMs. Biases in geographic distribution of study areas, and size and impervious surface cover of watersheds studied also limit our understanding of responses. We propose hysteretic trajectories for how watershed function responds to increasing imperviousness and stormwater management. Even where impervious area is treated with SCMs, watershed function may not be restored to its predevelopment condition because of the lack of treatment of all stormwater generated from impervious surfaces; non-additive effects of individual SCMs; and persistence of urban effects beyond impervious surfaces. In most cases, pollutant load decreases largely result from run-off reductions rather than lowered solute or particulate concentrations. Understanding interactions between natural and built landscapes, including stormwater management strategies, is critical for successfully managing detrimental impacts of stormwater at the watershed scale.

Europe↗
USGS2010

The use of scenario analysis to assess water ecosystem services in response to future land use change in the Willamette River Basin, Oregon

Human pressures on the natural resources of the United States have resulted in many unintended changes in our ecosystems, e.g., loss of biodiversity, habitat degradation, increases in the number of endangered species, and increases in contamination and water pollution. Environmental managers are concerned about broad-scale changes in land use and landscape pattern and their cumulative impact on hydrologic and ecological processes that affect stream conditions. The type of land use and land cover has direct consequences for most ecosystem services, including water quantity and water quality, erosion control, and biodiversity. As human pressure continues to increase, ecosystem services worldwide are projected to suffer continued loss and degradation, thus reducing the capacity of ecosystems to provide essential goods and services that contribute to human well-being (MEA 2005). The ability to assess, report, and forecast the life support functions of ecosystems is absolutely critical to our capacity to make informed decisions which will maintain the sustainable nature of our environmental services and secure these resources into the future. This study presents an integrated approach to identify areas with potential water quality problems as a result of land cover change projected by stakeholders within a moderately large river basin in the Pacific Northwest (USA). A process-based hydrologic watershed model was used to examine the contribution of land use/land cover to sediment yield, and nitrate and phosphorous loadings, and identify subwatersheds within the Willamette River basin that would be most affected in the year 2050 relative to three possible future scenarios which include inherent differences related to conservation, existing planning trends, and open development. Thus, the objective of this study was to evaluate the effects of alternative future scenarios that describe varying degrees of urban development and human use on hydrological response related to water quality. Results of this study suggest that the amount of forest along streams and agriculture consistently explained a high percentage of variation in nutrients. The AGWA-SWAT model was used to simulate change in sediment yield, nitrate and phosphorus transported with surface runoff for the three future scenarios. With regard to nitrate, the greatest increase was associated with subwatersheds with agricultural land use and urban areas. Although the model predicted some improvement in basin headwaters for all scenarios, nitrate loadings are expected to decrease under the conservation scenario. The largest decrease was observed in the Coast Range. With regard to phosphorous loadings, the lowest reduction was observed in subwatersheds draining predominantly forest areas. The greatest increase was observed under the open development scenario in subwatersheds with agricultural land use. Urbanization and agriculture are presumed to be the major environmental stressors affecting watershed condition of the Willamette River Basin.

Oregon↗
USGS2000

Nutrients and Suspended Solids in Surface Waters of the Upper Illinois River Basin in Illinois, Indiana, and Wisconsin, 1978-97

A retrospective analysis of selected data on nutrients and suspended solids in surface waters of the upper Illinois River Basin was done as part of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Approximately 91 percent of the upper Illinois River Basin is drained by three principal rivers: the Kankakee (and its major tributary, the Iroquois), the Des Plaines, and the Fox. The data analyzed were collected by the Illinois Environmental Protection Agency (IEPA), which operates 39 monitoring sites in the study area as part of its Ambient Water-Quality Monitoring Network, and included analyses for total ammonia nitrogen, total nitriteplus- nitrate nitrogen, total ammonia-plus-organic (total Kjeldahl) nitrogen, dissolved and total phosphorus, and total suspended solids and volatile solids. Nutrient and suspended-sediment data collected by the USGS as part of the upper Illinois River Basin NAWQA pilot study from 1987-90 were compared to IEPA data. For the 1978-97 period, in general, nutrient concentrations, with the exception of nitrate, were highest at streams in the urban areas of the Des Plaines River Basin. Streams in the Kankakee and Fox River Basins generally had lower concentrations, although the data indicate that concentrations increased in a downstream direction in these basins. These spatial patterns in nutrient concentrations correspond closely with land use in the respective basins. The elevated concentrations of ammonia and phosphorus in the urbanized Des Plaines River Basin, with respect to other sites in the study area, indicate that municipal- and industrial- waste discharges into streams of the basin increase concentrations of these nutrients in the receiving streams. In contrast, nitrate concentrations were highest in agricultural areas. Relatively large ratios of nitrogen to phosphorus and nitrate to ammonia are characteristic of agricultural drainage. On the other hand, urban tributaries were characterized by smaller ratios of nitrogen to phosphorus and nitrate to ammonia. The apparent, but nonuniform, correspondence of nutrient concentrations to urban and agricultural land use in the upper Illinois River Basin was generally consistent with findings in other river basins. A seasonal pattern of nutrient concentrations characterized by high concentrations in the winter months, depletion during the spring and summer, and minimum levels in the late summer or early fall was observed in some of the data from the upper Illinois River Basin. Monthly median concentrations of total ammonia nitrogen and nitrite plus nitrate nitrogen were at minimum levels from July through October, whereas phosphorus concentrations did not display a strong seasonal trend. The net result of nutrient inputs and transport through the river system were elevated nutrient concentrations at the most-downstream site in the study area on the Illinois River. At this site, the median concentrations of nitrate, total phosphorus, and orthophosphate were among the highest in the Mississippi River Basin, and the concentration of ammonia was the highest. Suspended-solids concentrations do not indicate any particularly strong spatial patterns among major river basins in the study area. Instead, higher suspended-solids concentrations are observed at sites draining areas of low-permeability, easily eroded soils in agricultural and urban areas alike. Seasonal variation of suspended solids were consistent at sites across the study area. In general, suspended- solids concentrations were highest in the summer and lowest in the winter. The increase during the summer can be attributed to higher streamflow and the associated increase in runoff and transport, as well as increased phytoplankton growth. Because of the high nutrient concentrations in the upper Illinois River Basin, annual loads and yields also were relatively large; however, yields of phosphorus from the Fox and Kankakee River Basins were not unusually high. The ma

Water-Resources Investigations Report↗
USGS2010

Sediment discharges during storm flow from proximal urban and rural karst springs, central Kentucky, USA

Since the mid-1990s, various studies have addressed the timing of sediment transport to karst springs during storm flow or the composition and provenance of sediment discharged from springs. However, relatively few studies have focused on the flow thresholds at which sediment is mobilized or total sediment yields across various time scales. We examined each of these topics for a mainly urban spring (Blue Hole) and a rural spring (SP-2) in the Inner Bluegrass region of central Kentucky (USA). Suspended sediment consisted mostly of quartz silt and sand, with lesser amounts of calcite and organic matter. Total suspended sediment (TSS) values measured during storm flow were greater at SP-2 than at Blue Hole. By aggregating data from four storms during 2 years, we found that median suspended-sediment size jumped as Q exceeded ???0.5 m 3 /s for both springs. At Blue Hole, TSS tended to vary with Q and capacity approached 1 g/L, but no systematic relationship between TSS and Q was evident at SP-2. Sediment fluxes from the Blue Hole basin were ???2 orders of magnitude greater for storms in March (2002 and 2004) than September (2002 and 2003). In contrast, sediment fluxes from the SP-2 basin were of similar magnitude in September 2003 and March 2004. The overall range of area-normalized fluxes for both springs, 9.16 ?? 10 -3 -4.45 ?? 10 2 kg/(ha h), overlaps values reported for farm plots and a stream in the Inner Bluegrass region and for other spring basins in the eastern USA and western Europe. Sediment compositions, sizes, and responses to storms in the basins may differ because of land use (e.g., the extent of impervious cover in the Blue Hole basin), basin size (larger for Blue Hole), conduit architecture, which appears to be more complex in the Blue Hole basin, and the impoundment of SP-2, which may have promoted decadal-scale storage of sediment upgradient. ?? 2009 Elsevier B.V. All rights reserved.

Journal of Hydrology↗
USGS2007

Measurement of atmospheric mercury species with manual sampling and analysis methods in a case study in Indiana

Ground-level concentrations of three atmospheric mercury species were measured using manual sampling and analysis to provide data for estimates of mercury dry deposition. Three monitoring stations were operated simultaneously during winter, spring, and summer 2004, adjacent to three mercury wet-deposition monitoring stations in northern, central, and southern Indiana. The monitoring locations differed in land-use setting and annual mercury-emissions level from nearby sources. A timer-controlled air-sampling system that contained a three-part sampling train was used to isolate reactive gaseous mercury, particulate-bound mercury, and elemental mercury. The sampling trains were exchanged every 6 days, and the mercury species were quantified in a laboratory. A quality-assurance study indicated the sampling trains could be held at least 120 h without a significant change in reactive gaseous or particulate-bound mercury concentrations. The manual sampling method was able to provide valid mercury concentrations in 90 to 95% of samples. Statistical differences in mercury concentrations were observed during the project. Concentrations of reactive gaseous and elemental mercury were higher in the daytime samples than in the nighttime samples. Concentrations of reactive gaseous mercury were higher in winter than in summer and were highest at the urban monitoring location. The results of this case study indicated manual sampling and analysis could be a reliable method for measurement of atmospheric mercury species and has the capability for supplying representative concentrations in an effective manner from a long-term deposition-monitoring network. ?? 2007 Springer Science+Business Media B.V.

Water, Air, & Soil Pollution↗
USGS2006

Approach to an assessment of volatile organic compounds in the nation's ground water and drinking-water supply wells

The National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS) developed an approach for a national assessment of the occurrence, status, and distribution of volatile organic compounds (VOCs) in samples of ground water from aquifer studies and in samples from drinking-water supply wells, specifically domestic and public wells. Data on VOCs in samples from aquifers and from domestic and public wells had three sources: (1) NAWQA sampling of ground water in aquifer studies and of shallow ground water in areas of agricultural or urban land use from 1993-2002, (2) retrospective data from other Federal, State, and local agencies that sampled ground water in aquifer studies from 1985-1997, and (3) sampling of ground water from public wells used as a source of drinking water from 1999-2000 (source-water survey). Data for assessing VOCs in ground water came from the NAWQA sampling of aquifers and from retrospective data (1 and 2). Domestic wells were the most commonly sampled well type in these aquifer studies. Data for assessing VOCs in domestic well samples came from the NAWQA sampling of aquifers and shallow ground water and from retrospective data (1 and 2). Data for assessing VOCs in public well samples came from NAWQA sampling of aquifers and shallow ground water and from the source-water survey (1, 2, and 3). Fifty-five VOCs were included in the national assessment. All ground-water samples were collected using consistent, prescribed field protocols and were analyzed using approved analytical methods. All ground-water collection activities and laboratory procedures included the collection of various quality-control samples in order to ensure the quality of the data. Comparisons of detection frequencies and detected concentrations among individual VOCs, groups of VOCs, aquifer studies, and data sets were performed using two assessment levels: (1) an assessment level of 0.2 microgram per liter (?g/L), and (2) an assessment level of 0.02 ?g/L. Selection of the 0.2-?g/L assessment level was based on historical laboratory reporting levels of VOCs used by the USGS National Water-Quality Laboratory (NWQL) prior to April 1996, and selection of the 0.02-?g/L assessment level was based on a new, low-level analytical method developed by the NWQL and used since April 1996. Relational analyses using multivariate logistic regression were performed on VOC data from aquifers, domestic wells, and public wells to better understand the natural and anthropogenic factors that control or influence the occurrence of VOCs. Ancillary data used in the relational analyses represent a variety of anthropogenic and hydrogeologic controls on the occurrence of VOCs. For aquifers, relational analyses were performed only on NAWQA data analyzed using the new low-level analytical method for 10 frequently detected VOCs. For domestic wells, relational analyses were performed at assessment levels of 0.2 ?g/L and 0.02 ?g/L for 6 and 10 frequently detected VOCs at these levels. For public wells, relational analyses were performed at an assessment level of 0.2 ?g/L for nine frequently detected VOCs.

Open-File Report↗
USGS2020

Quality Assurance Project Plan: Status and trends monitoring of small streams in the Puget Lowlands ecoregion for Stormwater Action Monitoring (SAM)

This Quality Assurance Project Plan (QAPP) details a long term status and trends monitoring study for small streams in the Puget Lowland as part of Stormwater Action Monitoring (SAM) program. SAM is the regional stormwater monitoring program funded by the Phase I Municipal Stormwater permit and the Western Washington Phase II Municipal Stormwater permit permittees. This study of small streams in the Puget Lowland Ecoregion (called Puget Small Streams, PSS study, or SAM_PSS study hereafter) is designed to answer the question, “Are regional conditions in receiving water quality and biota improving in concert with broad implementation of required stormwater management practices?” In 2015, the first round of monitoring evaluated the condition (status) of streams (DeGasperi et al., 2018). Beginning in 2020 and thereafter this study will monitor streams’ changes over time in urban, urbanizing and rural areas of the Puget Lowland. The PSS will follow the protocols developed for the on-going statewide stream health monitoring program-Status and Trends Monitoring for Watershed Health and Salmon Recovery (WHSR) for physical habitat, biological measurements, except for minor changes to water quality parameters to better capture the stormwater-related chemistry signals. In addition this effort will sample sieved sediments for stormwater-related chemistry signals. This QAPP ensures quality data collection, analysis, reporting and management of the SAM PSS monitoring study

Washington↗
USGS2007

GIS methodology for quantifying channel change in Las Vegas, Nevada

This study applies spatial analyses to examine the consequences of accelerated urban expansion on a hydrologic system over a period of 24 years. Three sets of historical aerial photos are used in a GIS analysis to document the geomorphic history of Las Vegas Wash, which drains the rapidly growing Las Vegas urban area in southern Nevada. New spatial techniques are introduced to make quantitative measurements of the erosion at three specific time intervals in the hydrologic evolution of the channel and floodplain. Unlike other erosion studies that use two different elevation surfaces to assess erosion, this study used a single elevation surface to remove systematic and nonsystemic elevation errors. The spatial analysis quantifies channel changes for discrete time periods, calculates erosion volumes, and provides a foundation to examine how the specific mechanisms related to urban expansion have affected Las Vegas Wash. The erosion calculated over 24 years is the largest documented sediment loss attributed to the effect of rapid urban growth. ?? 2007 American Water Resources Association.

Journal of the American Water Resources Associatio↗