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At least 865 records · Page 48Linked to original sources
USGS2008

Atlantic Flyway review: Region IV Piedmont-Coastal Plain, Fall 2007: Robbins Nest, Laurel, MD (390-0765)

After a gap of two years I resumed banding at this suburban fall-line station on the Patuxent River, my 33rd fall banding season on our two-acre wooded lot. I banded three mornings per week, trying to keep the same schedule as the Patuxent powerline station five miles downstream. I used half as many nets as they did and captured only 15% as many birds. Their location in a large undeveloped area combined with their managed shrub habitat probably accounted for most of the difference. The powerline station favored warblers and kinglets; I did better on cardinals and thrushes. I have witnessed a continuing decline in warblers. In 1997 and 1998 I was still getting four species of warblers among my top ten, and then two or three warbler species through 2004; 2007 was my first year with no warblers among my top ten species. My oldest recapture was a 1 0-year-old Gray Catbird (8051-36905) banded as an AHY on 18 Aug 1998.

Maryland↗
USGS2024

The effects of spatio-temporal variation in marine resources on the occupancy dynamics of a terrestrial avian predator

Identifying how species respond to system drivers such as weather, climate, habitat, and resource availability is critical in understanding population change. In coastal areas, the transfer of nutrients across the marine and terrestrial interface increases complexity. Nesting populations of bald eagles ( Haliaeetus leucocephalus ) along the Pacific coast of North America, although terrestrial, are largely dependent on marine resources during the breeding season and therefore represent a good focal species for understanding linkages of nutrients between terrestrial and marine systems. Due to their location, coastal eagle populations are susceptible to a variety of climate-induced perturbations, from both land and sea. The northeast Pacific Marine Heatwave (PMH) of 2014-2016 had wide-ranging impacts on the marine ecosystem and provided an opportunity to explore how marine conditions can impact terrestrial wildlife populations. We used a spatially-explicit multi-state occupancy modeling framework to analyze >30yrs of bald eagle nest occupancy data collected in four large national parks along a coastal-interior gradient in Alaska, USA. We assessed occupancy state in relation to weather conditions, salmon abundance, access to alternate prey resources, and the PMH event to help elucidate the factors affecting bald eagle occupancy dynamics over time. We found that occupancy probability was higher in areas where prey resources were concentrated (e.g., near seabird colonies, where bears facilitate access to salmon carcasses). We also found that the probability of reproductive success was higher during warmer, drier springs with higher-than-average salmon abundance. After the onset of the marine heatwave, success declined in the areas most dependent on non-salmon marine resources. These findings confirm the importance of spring weather conditions and access to salmon resources during the critical chick-rearing period, but also reveal that marine heatwaves may have important secondary effects through a reduction in the overall quantity or quality of prey available to bald eagles. Given ongoing warming at high latitudes and the expectation that marine heatwaves will become more common, our findings are useful for understanding ongoing and future changes in the transfer of nutrients from marine to terrestrial ecosystems and how such changes may impact terrestrial species such as bald eagles.

Alaska↗
USGS1972

Red fox spatial characteristics in relation to waterfowl predation

Radio-equipped red foxes ( Vulpes vulpes ) on the Cedar Creek area in Minnesota were spatially distributed, with individual families occupying well defined, nonoverlapping, contiguous territories. Territory boundaries often conformed to natural physical boundaries and appeared to be maintained through some nonaggressive behavior mechanism. Individual foxes traveled extensively throughout the family territory each night. Fox territories appeared to range from approximately 1 to 3 square miles in size, dependent largely on population density. Red foxes used a sequence of dens to rear their pups, and the amount and location of food remains at individual dens changed as the pups matured. The denning season was divided into pre-emergence, confined-use, and dispersed-use periods of 4 to 5 weeks each. Remains of adult waterfowl were collected at rearing dens on six townships in three ecologically different regions of eastern North Dakota. Remains of 172 adult dabbling ducks and 16 adult American coots (Fulica americana) were found at 35 dens. No remains from diving ducks were found. The number of adult ducks per den averaged 1.6, 5.9, and 10.2 for paired townships in regions with relatively low, moderate and high duck populations, respectively. Eighty-four percent of the ducks were females. The species and sex composition of ducks found at dens during early and late sampling periods reflected the nesting chronology of prairie dabbling ducks. Occupied rearing dens were focal points of red fox travel, and the locations of dens may have had considerable influence on predation. Thirty-five of 38 dens found on the six township study areas were on pastured or idle lands. The distribution of rearing dens on the Sand Lake and Arrowwood national wildlife refuges suggested that, on these areas, fox dens were concentrated because of the topography and land-use practices.

Minnesota↗
USGS2001

Concentrations and annual fluxes for selected water-quality constituents from the USGS National Stream Quality Accounting Network (NASQAN) 1996-2000

This report contains concentrations and annual mass fluxes (loadings) for a broad range of water-quality constituents measured during 1996-2000 as part of the U.S. Geological Survey National Stream Quality Accounting Network (NASQAN). During this period, NASQAN operated a network of 40-42 stations in four of the largest river basins of the USA: the Colorado, the Columbia, the Mississippi (including the Missouri and Ohio), and the Rio Grande. The report contains surface-water quality data, streamflow data, field measurements (e.g. water temperature and pH), sediment-chemistry data, and quality-assurance data; interpretive products include annual and average loads, regression parameters for models used to estimate loads, sub-basin yield maps, maps depicting percent detections for censored constituents, and diagrams depicting flow-weighted average concentrations. Where possible, a regression model relating concentration to discharge and season was used for flux estimation. The interpretive context provided by annual loads includes identifying source and sink areas for constituents and estimating the loadings to receiving waters, such as reservoirs or the ocean.

Water-Resources Investigations Report↗
USGS1992

Effects of dried wastewater-treatment sludge application on ground-water quality in South Dade County, Florida

Four test fields in the south Dade agricultural area were studied to determine the effects of sludge application on ground-water quality. Two fields had been cultivated for 10 years or more, and two had not been farmed for at least 10 years. The fields were representative of the area's two soil types (Rockdale and Perrine marl) and two major crop types (row crops and groves). Before the application of sludge, wells upgradient of, within, and downgradient of each field were sampled for possible sludge contaminants at the end of wet and dry seasons. Municipal wastewater treatment sludge from the Dade County Water and Sewe Authority Department was then applied to the fields at varying application rates. The wells at each field were sampled over a 2-year period under different hydrologic conditions for possible sludge-related constituents (specific conductance, pH, alkalinity, nitrogen, phosphorus, total organic carbon, copper, iron, magnesium, manganese, potassium, zinc, arsenic, cadmium, chloride, chromium, lead, mercury, nickel, and sodium). Comparisons were made between water quality in the vicinity of the test fields and Florida Department of Environmental Regulation primary and secondary drinking-water regulations, an between water quality upgradient of, beneath, and downgradient of the fields. Comparisons between presludge and postsludge water quality did not indicate any improvement because of retention of agrichemicals by the sludge nor did they indicate any deterioration because of leaching from the sludge. Comparisons of water quality upgradient of the fields to water quality beneath and downgradient of the fields also did not indicate any changes related to sludge. Florida Department of Environmental Regulation primary and secondary drinking-water regulations wer exceeded at the Rockdale maximum-application field by mercury (9.5 ug/L (micrograms per liter)), and the Perrine marl maximum-application field by manganese (60 ug/L) and lead (85 ug/L), and at the Perrine marl row-crop field by mercury (5.2 ug/L). All other exceedances were either in presludge or upgradient samples, or they were for constituents or properties, such as iron and color, which typically exceed standards in native ground water. Acid-extractable and base-neutral compounds, volatile organic compounds, chlorophenoxy herbicides, organophosphorus insecticides, and organochlorine compounds were analyzed for one shallow well at each field twice annually. Those compounds that equaled or exceeded the detection limit after sludge was applied included benzene (0.3 and 1.2 ug/L), chloroform (0.2 and 0.3 ug/L), bis(2-Ethylhexyl)phthalate (29 and 42 ug/L), methylene chloride (14 ug/L), tolulene (0.2, 0.4, 0.5, 1.3, and 4.4 ug/L), 1, 1,1-trichloroethana (0.6 ug/L), trichloroethylene (0.3 ug/L), 2.4-D (0.01 ug/L), and xylene (0.3 ug/L). It ws not possible to ascertain the origin of these compounds because they are available from sources other than sludge.

Water-Resources Investigations Report↗
USGS1972

Effect of certain anesthetic agents on mallard ducks

Four anesthetic agents used in human or veterinary medicine and 3 experimental anesthetic preparations were evaluated for effectiveness in inducing narcosis when administered orally to game-farm mallard ducks (Anas platyrhynchos).Tribromoethanol was the only compound to satisfy criteria of initial tests. Mean duration of the induction, immobilization, and recovery periods was 2.4 minutes, 8.7 minutes, and 1.3 hours, respectively, at the median effective dosage for immobilization (ED50; 100 mg./kg. of body weight). The median lethal dosage (LD50) was 400 mg./kg. of body weight.Tribromoethanol was also tested on mallards during the reproductive season. Effects on the hatchability of eggs or the survival of young were not detected.

Journal of the American Veterinary Medical Associa↗
USGS2004

Subarctic, alpine nesting by Bairds Sandpipers Calidris bairdii

Baird's Sandpipers Calidris bairdii were found nesting in alpine habitat in southwestern Alaska (60°48'N, 154°00'W), almost 250 km from the nearest known breeding site, and studied over three consecutive seasons, 1997-1999. The first birds arrived during the second week of May each spring with peak numbers recorded the third week of May. Most nests and newly hatched broods were found on sparsely vegetated dwarf shrub-lichen mat tundra on level or gently sloping areas throughout the alpine zone between 980 and 1400 m above sea level. Most eggs hatched during the third week of June and independent young were noted during the second and third weeks of July. Both parents initially tended broods, but only the male remained after chicks were about four days of age. During early brood-rearing, adults began to move chicks, often to higher elevations and over distances of several hundred metres. Throughout the area the density of nesting birds was about 0.2 pairs/km 2 with up to 0.9 pairs/km 2 found on southerly exposures of the north study slope. A summary of available information revealed the global nesting distribution of bairdii to be strongly associated with disturbed landscapes, especially montane areas affected by glaciation, suggesting the breeding range is likely to be much more extensive than currently known, especially in areas of Alaska, the Yukon, and possibly Chukotka.

Alaska↗
USGS2022

Long-term suspended sediment and particulate organic carbon yields from the Reynolds Creek Experimental Watershed and Critical Zone Observatory

Long-term (>20 y) suspended sediment (SS) and particulate organic carbon (POC) records are relatively rare and yet are necessary for understanding linkages between climate, erosion and carbon export. We estimated long-term (>23 y) SS and POC yields from four nested catchments that ranged from <1 to 54 km 2 in area across the Reynolds Creek Experimental Watershed and Critical Zone Observatory (RCEW-CZO) in southwestern Idaho, USA. We found strong relationships between log 10 SS and log 10 POC (R 2 = 0.38–0.86) that varied across catchments but remained robust across years, one dry and one of the wettest water years on record. Mean annual SS yields varied from 18 to 89 g SS m −2 y −1 and POC from 0.6 to 11.0 g C m −2 y −1 across the four catchments. Water yield explained much of the temporal variation (72%–85%) in SS and POC yields except in a small, snow-dominated headwater catchment where it explained 15%–51%. The largest five water years accounted for 69%–84% of the total SS and POC yields in catchments with 24 y records. All catchments had positive slopes (>0) for SS and POC concentration-discharge (C-Q) relationships, with large catchments exhibiting greater slopes (0.66–0.97) than smaller ones (0.14–0.16). In addition, most catchments were dominated (80%) by clockwise hysteretic curves. Lack of seasonal exhaustion in the SS-POC relationships, positive C-Q and clockwise relations indicated that these systems were transport-rather than supply limited, and that sediment and POC appeared to be sourced from channel/bank erosion and remobilization. POC yields represent 1%–10% of mean water year net ecosystem exchange depending on elevation; lower elevation catchments may shift from being carbon sinks to sources after accounting for fluvial POC export associated with changes in climate.

Idaho↗
USGS2017

Fusing MODIS with Landsat 8 data to downscale weekly normalized difference vegetation index estimates for central Great Basin rangelands, USA

Data fused from distinct but complementary satellite sensors mitigate tradeoffs that researchers make when selecting between spatial and temporal resolutions of remotely sensed data. We integrated data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor aboard the Terra satellite and the Operational Land Imager sensor aboard the Landsat 8 satellite into four regression-tree models and applied those data to a mapping application. This application produced downscaled maps that utilize the 30-m spatial resolution of Landsat in conjunction with daily acquisitions of MODIS normalized difference vegetation index (NDVI) that are composited and temporally smoothed. We produced four weekly, atmospherically corrected, and nearly cloud-free, downscaled 30-m synthetic MODIS NDVI predictions (maps) built from these models. Model results were strong with R 2 values ranging from 0.74 to 0.85. The correlation coefficients ( r ≥ 0.89) were strong for all predictions when compared to corresponding original MODIS NDVI data. Downscaled products incorporated into independently developed sagebrush ecosystem models yielded mixed results. The visual quality of the downscaled 30-m synthetic MODIS NDVI predictions were remarkable when compared to the original 250-m MODIS NDVI. These 30-m maps improve knowledge of dynamic rangeland seasonal processes in the central Great Basin, United States, and provide land managers improved resource maps.

Great Basin rangelands↗
USGS2022

Kittlitz’s murrelet seasonal distribution and post-breeding migration from the Gulf of Alaska to the Arctic Ocean

Kittlitz’s Murrelets ( Brachyramphus brevirostris ) nest during summer in glaciated or recently deglaciated (post-Wisconsin) landscapes. They forage in adjacent marine waters, especially those influenced by glacial meltwater. Little is known of their movements and distribution outside the breeding season. To identify post-breeding migrations of murrelets, we attached satellite transmitters to birds (n = 47) captured at sea in the Gulf of Alaska and Aleutian Islands during May – July 2009 – 15 and tracked 27 birds that migrated from capture areas. Post-breeding murrelets migrated toward the Bering Sea, with short periods of movement (median 2 d) separated by short stopovers (median 1 d). Travel speeds averaged 79.4 km d-1 (83.5 SD, 449.1 maximum). Five Kittlitz’s Murrelets tagged in Prince William Sound in May migrated to the Bering Sea by August and four continued north to the Arctic Ocean, logging 2500 – 4000 km of travel. Many birds spent 2‒3 weeks with little movement along coasts of the Alaska Peninsula or eastern Bering Sea during late August through September, also the pre-basic molt period. Ship-based surveys, many of which were conducted concurrently with our telemetry studies, confirmed that substantial numbers of Kittlitz’s Murrelets migrate into the Arctic Ocean during autumn. They also revealed that some birds spend winter and spring in the Bering Sea in association with ice-edge, polynya, or marginal ice zone habitats before returning to summer breeding grounds. We conclude that this species is best characterized as a sub-Arctic and Arctic species, which has implications for future risk assessments and threat mitigation.

Alaska↗
USGS1996

Natural thermal refugia for temperate warmwater stream fishes

The seasonal use of an Ozark spring branch by fishes was evaluated from January 1993 to January 1995. Temperatures in the spring branch were fairly constant, at 13.5 ± 1°C, and usually exceeded the temperature of a receiving stream during the November–March coldwater period. Black redhorse Moxostoma duquesnei , smallmouth bass Micropterus dolomieu , shadow bass Ambloplites ariommus , and longear sunfish Lepomis megalotis showed a temporal pattern of use in the spring branch. The lowest use was during the April–October warmwater period, and the greatest use was during the coldwater period. During cold periods, biomass of these four species in the spring branch was significantly greater and fish size significantly larger than in similar habitats in the adjoining stream. The weight per unit length of fish using the spring branch during cold periods was also significantly greater. Shadow bass and longear sunfish had significantly greater relative stomach contents than conspecifics in equivalent habitats from the adjoining stream, but had similar relative numbers of eggs. Large concentrations of adult fish used spring branches during the coldwater period, and these fish may be more vulnerable to angling than conspecifics in similar habitats in adjoining streams dominated by surface water. Thus, we suggest that stream managers consider the usefulness of fish refuges in spring branches and adjacent thermally influenced areas.

Missouri↗
USGS2004

Effects of reservoir installation, San Juan-Chama Project water, and reservoir operations on streamflow and water quality in the Rio Chama and Rio Grande, northern and central New Mexico, 1938-2000

The coordinated operation of Heron, El Vado, and Abiquiu Dams on the Rio Chama and Cochiti Dam on the Rio Grande and the importation of Colorado River Basin water by the San Juan-Chama Project have altered streamflow and water quality of the Rio Chama and Rio Grande in northern and central New Mexico. The coordinated retention of streamflow in the four reservoirs increased median streamflows, decreased extreme flows, and decreased periods of small streamflow; inflow of San Juan-Chama Project water increased overall streamflow in the Rio Chama and Rio Grande. These changes to streamflow decreased specific conductance and suspended-sediment concentration and increased pH in the Rio Chama and the Rio Grande. Following construction of Heron and Cochiti Dams and integration of reservoir operations on the Rio Chama and the Rio Grande, the inflow of San Juan-Chama Project water and retention of snowmelt runoff influenced water quality. These influences varied by season because reservoir releases fluctuated according to downstream user needs and annual streamflow variation. The influences of San Juan-Chama Project water and retained snowmelt on water quality diminished with downstream flow as the Rio Grande was subjected to various natural and anthropogenic inflows. Because of the variability and type of seasonal influences, streamflow did not have a strong annual correlation with water quality in the Rio Chama or the Rio Grande.

Scientific Investigations Report↗
USGS2010

Analysis of elevation changes detected from multi-temporal LiDAR surveys in forested landslide terrain in western Oregon

We examined elevation changes detected from two successive sets of Light Detection and Ranging (LiDAR) data in the northern Coast Range of Oregon. The first set of LiDAR data was acquired during leafon conditions and the second set during leaf-off conditions. We were able to successfully identify and map active landslides using a differential digital elevation model (DEM) created from the two LiDAR data sets, but this required the use of thresholds (0.50 and 0.75 m) to remove noise from the differential elevation data, visual pattern recognition of landslideinduced elevation changes, and supplemental QuickBird satellite imagery. After mapping, we field-verified 88 percent of the landslides that we had mapped with high confidence, but we could not detect active landslides with elevation changes of less than 0.50 m. Volumetric calculations showed that a total of about 18,100 m3 of material was missing from landslide areas, probably as a result of systematic negative elevation errors in the differential DEM and as a result of removal of material by erosion and transport. We also examined the accuracies of 285 leaf-off LiDAR elevations at four landslide sites using Global Positioning System and total station surveys. A comparison of LiDAR and survey data indicated an overall root mean square error of 0.50 m, a maximum error of 2.21 m, and a systematic error of 0.09 m. LiDAR ground-point densities were lowest in areas with young conifer forests and deciduous vegetation, which resulted in extensive interpolations of elevations in the leaf-on, bare-earth DEM. For optimal use of multi-temporal LiDAR data in forested areas, we recommend that all data sets be flown during leaf-off seasons.

Environmental & Engineering Geoscience↗
USGS2007

Water-Quality Characteristics for Sites in the Tongue, Powder, Cheyenne, and Belle Fourche River Drainage Basins, Wyoming and Montana, Water Years 2001-05, with Temporal Patterns of Selected Long-Term Water-Quality Data

Water-quality sampling was conducted regularly at stream sites within or near the Powder River structural basin in northeastern Wyoming and southeastern Montana during water years 2001-05 (October 1, 2000, to September 30, 2005) to characterize water quality in an area of coalbed natural gas development. The U.S. Geological Survey, in cooperation with the Wyoming Department of Environmental Quality, characterized the water quality at 22 sampling sites in the Tongue, Powder, Cheyenne, and Belle Fourche River drainage basins. Data for general hydrology, field measurements, major-ion chemistry, and selected trace elements were summarized, and specific conductance and sodium-adsorption ratios were evaluated for relations with streamflow and seasonal variability. Trend analysis for water years 1991-2005 was conducted for selected sites and constituents to assess change through time. Average annual runoff was highly variable among the stream sites. Generally, streams that have headwaters in the Bighorn Mountains had more runoff as a result of higher average annual precipitation than streams that have headwaters in the plains. The Powder River at Moorhead, Mont., had the largest average annual runoff (319,000 acre-feet) of all the sites; however, streams in the Tongue River drainage basin had the highest runoff per unit area of the four major drainage basins. Annual runoff in all major drainage basins was less than average during 2001-05 because of drought conditions. Consequently, water-quality samples collected during the study period may not represent long-term water-quality con-ditions for all sites. Water-quality characteristics were highly variable generally because of streamflow variability, geologic controls, and potential land-use effects. The range of median specific-conductance values among sites was smallest in the Tongue River drainage basin. Median values in that basin ranged from 643 microsiemens per centimeter at 25 degrees Celsius (?S/cm at 25?C) on the Tongue River to 1,460 ?S/cm at 25?C on Prairie Dog Creek. The Tongue River drainage basin has the largest percentage of area underlain by Mesozoic-age and older rocks and by more resistant rocks. In addition, the higher annual precipitation and a steeper gradient in this basin compared to basins in the plains produce relatively fast stream velocities, which result in a short contact time between stream waters and basin materials. The Powder River drainage basin, which has the largest drainage area and most diverse site conditions, had the largest range of median specific-conductance values among the four major drainage basins. Median values in that basin ranged from 680 ?S/cm at 25?C on Clear Creek to 5,950 ?S/cm at 25?C on Salt Creek. Median specific-conductance values among sites in the Cheyenne River drainage basin ranged from 1,850 ?S/cm at 25?C on Black Thunder Creek to 4,680 ?S/cm at 25?C on the Cheyenne River. The entire Cheyenne River drainage basin is in the plains, which have low precipitation, soluble geologic materials, and relatively low gradients that produce slow stream velocities and long contact times. Median specific-conductance values among sites in the Belle Fourche River drainage basin ranged from 1,740 ?S/cm at 25?C on Caballo Creek to 2,800 ?S/cm at 25?C on Donkey Creek. Water in the study area ranged from a magnesium-calcium-bicarbonate type for some sites in the Tongue River drainage basin to a sodium-sulfate type at many sites in the Powder, Cheyenne, and Belle Fourche River drainage basins. Little Goose Creek, Goose Creek, and the Tongue River in the Tongue River drainage basin, and Clear Creek in the Powder River drainage basin, which have headwaters in the Bighorn Mountains, consistently had the smallest median dissolved-sodium concentrations, sodium-adsorption ratios, dissolved-sulfate concentrations, and dissolved-solids concentrations. Salt Creek, Wild Horse Creek, Little Powder River, and the Cheyenne River, which have headwat

Scientific Investigations Report↗
USGS1986

Review of the hydrologic data-collection network in the St. Joseph River basin, Indiana

The St. Joseph River Basin data-collection network in the St. Joseph River for streamflow, lake, ground water, and climatic stations was reviewed. The network review included only the 1700 sq mi part of the basin in Indiana. The streamflow network includes 11 continuous-record gaging stations and one partial-record station. Based on areal distribution, lake effect , contributing drainage area, and flow-record ratio, six of these stations can be used to describe regional hydrology. Gaging stations on lakes are used to collect long-term lake-level data on which to base legal lake levels, and to monitor lake-level fluctuations after legal levels are established. More hydrogeologic data are needed for determining the degree to which grouhd water affects lake levels. The current groundwater network comprises 15 observation wells and has four purposes: (1) to determine the interaction between groundwater and lakes; (2) to measure changes in groundwater levels near irrigation wells; (3) to measure water levels in wells at special purpose sites; and (4) to measure long-term changes in water levels in areas not affected by pumping. Seven wells near three lakes have provided sufficient information for correlating water levels in wells and lakes but are not adequate to quantify the effect of groundwater on lake levels. Water levels in five observation wells located in the vicinity of intensive irrigation are not noticeably affected by seasonal withdrawals. The National Weather Sevice operates eight climatic stations in the basin primarily to characterize regional climatic conditions and to aid in flood forecasting. The network meets network-density guidelines established by the World Meterological Organization for collection of precipitation and evaporation data but not guidelines suggested by the National Weather Service for density of precipitation gages in areas of significant convective rainfalls. (Author 's abstract)

Indiana↗
USGS2008

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

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

Scientific Investigations Report↗
USGS1995

Water quality of the Boca Raton canal system and effects of the Hillsboro Canal inflow, southeastern Florida, 1990-91

The City of Boca Raton in southeastern Palm Beach County, Florida, is an urban residential area that has sustained a constant population growth with subsequent increase in water use. The Boca Raton network of canals is controlled to provide for drainage of excess water, to maintain proper coastal ground-water levels to prevent saltwater intrusion, and to recharge the surficial aquifer system from which the city withdraws potable water. Most of the water supplied to the Boca Raton canal system and the surficial aquifer system, other than rainfall and runoff, is pumped from the Hillsboro Canal. The Biscayne aquifer, principal hydrogeologic unit of the surficial aquifer system, is highly permeable and there is a close relation between water levels in the canals and the aquifer. The amount of water supplied by seepage from the conservation areas is unknown. Because the Hillsboro Canal flows from Lake Okeechobee and Water Conservation Areas 1 and 2, which are places of more highly mineralized ground water and surface water, the canal is a possible source of contamination. Water samples were collected at 10 canal sites during wet and dry seasons and analyzed for major inorganic ions and related characteristics, nutrients, and trace elements. All concentrations were generally within or less than the drinking-water standards established by the Florida Department of Environmental Protection. The high concentrations of sodium and chloride that were detected in samples from the Boca Raton canal system are probably from the more mineralized water of the Hillsboro Canal. Other water-quality data, gathered from various sources from 1982 through 1991, did not indicate any significant changes nor trends. The data include pesticide and metal analyses of water samples and bottom sediments collected at four canal sites in the Boca Raton study area by the U.S. Geological Survey during 1982-84. The effects of the Hillsboro Canal on the water quality of the Boca Raton canal system are indicated by increased concentrations of sodium, chloride, dissolved solids, and total organic carbon. Concentrations of the constituents in the canal water generally decrease with distance from the Hillsboro Canal pumping station and are the result of dilution by receiving canal waters.

Florida↗
USGS2022

Hydrological and lock operation conditions associated with paddlefish and bigheaded carp dam passage on a large and small scale in the Upper Mississippi River (Pools 14–18)

Movement and dispersal of migratory fish species is an important life-history characteristics that can be impeded by navigation dams. Although habitat fragmentation may be detrimental to native fish species, it might act as an effective and economical barrier for controlling the spread of invasive species in riverine systems. Various technologies have been proposed as potential fish deterrents at locks and dams to reduce bigheaded carp (i.e., silver carp and bighead carp ( Hypophthalmichthys spp.)) range expansion in the Upper Mississippi River (UMR). Lock and Dam (LD) 15 is infrequently at open-river condition (spillway gates completely open; hydraulic head across the dam <0.4 m) and has been identified as a potential location for fish deterrent implementation. We used acoustic telemetry to evaluate paddlefish passage at UMR dams and to evaluate seasonal and diel movement of paddlefish and bigheaded carp relative to environmental conditions and lock operations at LD 15. We observed successful paddlefish passage at all dams, with the highest number of passages occurring at LDs 17 and 16. Paddlefish residency events in the downstream lock approach of LD 15 occurred more frequently and for longer durations than residency events of bigheaded carp. We documented upstream passages completed by two individual paddlefish through the lock chamber at LD 15, and a single bighead carp completed upstream passage through the lock chamber during two separate years of this study. We identified four bigheaded carp and 19 paddlefish that made upstream passages through the spillway gates at LD 15 during this study. The majority of the upstream passages through the spillway gates for both species occurred during open river conditions. When hydraulic head was approximately 1-m or greater, we observed these taxa opt for upstream passage through the lock chamber more often than the dam gates. In years with infrequent open-river condition, a deterrent placed in the downstream lock approach may assist in meeting the management goal of reducing upstream passage of bigheaded carps but could also potentially affect paddlefish residency and passage. Continued study to understand the effects of deterrents on native fish could be beneficial for implementing an integrated bigheaded carp control strategy. Understanding fish behavior at UMR dams is a critical information need for river managers as they evaluate potential tools or technologies to control upstream expansion of bigheaded carp in the UMR.

Illinois, Iowa↗