USGS Science⌕ Search

SEARCH · USGS Science

Results for “Rivers”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources
USGS1985

Distribution and transport of trace substances in the Schuylkill River basin from Berne to Philadelphia, Pennsylvania

During the period from October 1978 to March 1981, the U.S. Geological Survey assessed the river quality of the Schuylkill River basin in Pennsylvania from the headwaters to the Fairmount Dam at Philadelphia (river mile 8.4). The assessment focused on the distribution and transport of trace metals and organic substances (trace substances). Trace metals included were arsenic, beryllium, cadmium, copper, lead, mercury, nickel, and zinc; trace organic substances included organochlorine insecticides and polychlorinated biphenyls. In general, concentrations of trace substances in the streambed sediments were greater in the main stem of the Schuylkill River than in its tributaries and exceeded the background concentrations in the study area. Concentrations of most trace metals in the sediments were lowest in the Berne area (river mile 95) and highest in the urban-industrial area of Reading (river mile 76). Concentrations generally decreased from Reading downstream to Philadelphia (river mile 10.2). Concentrations of the organochlorine insecticides chlordane, DDT and its metabolites, and dieldrin generally increased gradually from Berne to Philadelphia. Average concentrations of trace metals in the main stem of the Schuylkill River in the sediment-sized fraction, less than 0.063 millimeters, were: zinc, 603 ?g/g (micrograms per gram); lead, 284 ?g/g; copper, 252 ?g/g; nickel, 119 ?g/g; chromium, 96 ?g/g; beryllium, 8.2 ?g/g; arsenic, 0.64 ?g/g; and mercury, 0.002 ?g/g. Average concentrations of trace organic substances in sediments of the main stem of the river were: polychlorinated biphenyls, 152 ?g/kg (micrograms per kilogram); chlordane, 24 ?g/kg; DDT and its metabolites, 18 ?g/kg; and dieldrin, 1.8 ?g/kg. The average annual transport of trace substances by the river was computed for chromium, copper, lead, nickel, and zinc. Concentrations of other trace substances in the sediment-water mixtures were generally undetectable. Of the trace metals, average annual transport of zinc was the greatest, and that of nickel was the least. Transport of trace metals in the river is closely associated with and related to suspended-sediment transport. About 71 percent of the average annual total metal transport is particulate material. Yields, in tons per square mile per year, of copper, lead, zinc, and total organic carbon in the Schuylkill River basin were compared with yields in the Chattahoochee River basin (Georgia). The comparison indicates that yields, by constituent, were of the same order of magnitude. Both basins lie in the Piedmont province, and both have about the same percentage of urban land use. The frequency of occurrence of concentrations of copper, lead, and zinc in the sediment-water mixture at Manayunk in Philadelphia were compared with domestic water-supply criteria of the U.S. Environmental Protection Agency. The criteria are exceeded less than 1 percent of the time, or about 4 days per year.

Schuylkill River basin↗
USGS1937

The floods of March 1936, part 1, New England rivers

During the period March 9-22, 1936, there occurred in close succession over the northeastern United States, from the James and upper Ohio River Basins in Virginia and Pennsylvania to the river basins of Maine, two extraordinarily heavy storms, in which the precipitation was almost entirely in the form of rain. The depths of rainfall mark this period as one of the greatest concentrations of precipitation, in respect to time and magnitude of the area covered, of which there is record in this country. At the time of the rain there were also accumulations of snow on the ground over much of the storm-affected region that were large for the season. The comparatively warm temperatures associated with the storms thawed the snow and added materially to the quantities of water to be disposed of by drainage into the waterways, by surface storage in lakes, ponds, and reservoirs, by absorption in the ground, and, probably in comparatively negligible degree, by evaporation. The total quantity of water that had to be disposed of in these ways ranged between 10 and 30 inches in depth over much of the region. The water disposed of by natural storage, absorption, and evaporation amounted to average depths over the many river basins generally within the range of 1 to 3 inches, with a significant degree of uniformity and systematic areal distribution. The remainder of the rain and snow water, generally much larger or even several times larger in amount than surface storage, absorption, and evaporation, required accommodation by the channels of the brooks, creeks, and rivers. There were generally two distinct flood peaks, and in many of the basins the destruction was seriously aggravated, especially during the first flood, by the break-up of thick ice cover accumulated through a winter of exceptionally continuous and severe cold weather. The resulting floods were extraordinarily severe, and records of river stages, extending on some streams back to or nearly to the time of settlement by white men, were broken many of them by wide margins. The peak of the Connecticut River at Hartford, Conn., was 8.6 feet higher than had been experienced since the settlement by white men, 300 years ago. The Susquehanna River at Harrisburg, Pa., was 3.5 feet higher than had been known in a period of record covering about 200 years. The Ohio River at Pittsburgh, Pa., was 6.1 feet higher than had been known in the period beginning 1762. This volume presents many of the facts of these notable floods with respect to the New England rivers, for permanent record and for study and reference by engineers concerned with the building of highways, bridges, and industrial plants, planners of river development, and others. Similar volumes for the region from the Hudson River to the Susquehanna River and for the Potomac, James, and upper Ohio River Basins are presented in companion Water-Supply Papers 799 and 800 respectively. In this volume records of stage and discharge for the period Including the floods are presented for about 150 measurement stations; peak discharges with comparative data for other floods at more than 400 measurement points are summarized; crest stages along an aggregate length of stream channel of 2,820 miles are tabulated; and results of detailed studies of the rainfall and run-off and many other kinds of flood information are presented.

Water Supply Paper↗
USGS1937

The floods of March 1936, Part 3, Potomac, James, and upper Ohio Rivers

During the period March 9-22, 1936, there occurred in close succession over the northeastern United States, from the James and upper Ohio River Basins in Virginia and Pennsylvania to the river basins of Maine, two extraordinarily heavy storms, in which the precipitation was almost entirely in the form of rain. The depths of rainfall mark this period as one of the greatest concentrations of precipitation, in respect to time and magnitude of the area covered, of which there is record in this country. At the time of the rain there were also accumulations of snow on the ground over much of the storm-affected region that were large for the season. The comparatively warm temperatures associated with the storms thawed the snow and added materially to the quantities of water to be disposed of by drainage into the waterways, by surface storage in lakes, ponds, and reservoirs, by absorption in the ground, and, probably in comparatively negligible degree, by evaporation. The total quantity of water that had to be disposed of in these ways ranged between 10 and 30 inches in depth over much of the region. The water disposed of by natural storage, absorption, and evaporation amounted to average depths over the many river basins generally within the range of 1 to 3 inches, with a significant degree of uniformity and systematic areal distribution. The remainder of the rain and snow water, generally much larger or even several times larger in amount than surface storage, absorption, and evaporation, required accommodation by the channels of the brooks, creeks, and rivers. There were generally two distinct flood peaks, and in many of the basins the destruction was seriously aggravated, especially during the first flood, by the break-up of thick ice cover accumulated through a winter of exceptionally continuous and severe cold weather. The resulting floods were extraordinarily severe, and records of river stages, extending on some streams back to or nearly to the time of settlement by white men, were broken many of them by wide margins. The peak of the Connecticut River at Hartford, Conn., was 8.6 feet higher than had been experienced since the settlement by white men, 300 years ago. The Susquehanna River at Harrisburg, Pa., was 3.5 feet higher than had been known in a period of record covering about 200 years. The Ohio River at Pittsburgh, Pa., was 6.1 feet higher than had been known in the period beginning 1762. This volume presents many of the facts of these notable floods with respect to the New England rivers, for permanent record and for study and reference by engineers concerned with the building of highways, bridges, and industrial plants, planners of river development, and others. Similar volumes for the region from the Hudson River to the Susquehanna River and for the Potomac, James, and upper Ohio River Basins are presented in companion Water-Supply Papers 799 and 800 respectively. In this volume records of stage and discharge for the period Including the floods are presented for about 150 measurement stations; peak discharges with comparative data for other floods at more than 400 measurement points are summarized; crest stages along an aggregate length of stream channel of 2,820 miles are tabulated; and results of detailed studies of the rainfall and run-off and many other kinds of flood information are presented.

Water Supply Paper↗
USGS2025

Movements and habitat use of Silver Carp in the Arkansas and White rivers

Silver Carp Hypophthalmichthys molitrix is an invasive species found throughout the Mississippi River basin. Efforts have been made to control Silver Carp populations through removal programs and movement barrier implementation. Up to date information on diel, seasonal, and annual movements and habitat use by Silver Carp will benefit these efforts. Studies of Silver Carp movement are prevalent in the upper Mississippi River, Ohio River, and tributaries, but rare in tributaries of the lower Mississippi River. Between June 2021 and May 2022, we quantified average movement rates and residency periods of 48 Silver Carp in the free-flowing lower White River and lock-and-dam fragmented lower Arkansas River using passive acoustic telemetry arrays and internal implant acoustic transmitters. We also manually tracked Silver Carp in the two rivers during the four seasons to estimate diel movement rates and use of different habitats. On an annual scale, Silver Carp in the White River moved at faster rates than Silver Carp in the Arkansas River and were recorded more times by acoustic receivers. Diel movement rates varied by season in both rivers but were low overall. Silver Carp used lentic habitats more often than lotic habitats. Overall, results suggest the numerous locks and dams of the McClellan-Kerr Arkansas River Navigation System may limit large-scale, annual movement of Silver Carp in the Arkansas River compared to the White River. Low hourly diel movement rates and high occupancy of lentic habitats also should enable effective harvest of Silver Carp using active gears in those lentic habitats.

Arkansas↗
USGS2004

Modeling a three-dimensional river plume over continental shelf using a 3D unstructured grid model

River derived fresh water discharging into an adjacent continental shelf forms a trapped river plume that propagates in a narrow region along the coast. These river plumes are real and they have been observed in the field. Many previous investigations have reported some aspects of the river plume properties, which are sensitive to stratification, Coriolis acceleration, winds (upwelling or downwelling), coastal currents, and river discharge. Numerical modeling of the dynamics of river plumes is very challenging, because the complete problem involves a wide range of vertical and horizontal scales. Proper simulations of river plume dynamics cannot be achieved without a realistic representation of the flow and salinity structure near the river mouth that controls the initial formation and propagation of the plume in the coastal ocean. In this study, an unstructured grid model was used for simulations of river plume dynamics allowing fine grid resolution in the river and in regions near the coast with a coarse grid in the far field of the river plume in the coastal ocean, in the vertical, fine fixed levels were used near the free surface, and coarse vertical levels were used over the continental shelf. The simulations have demonstrated the uniquely important role played by Coriolis acceleration. Without Coriolis acceleration, no trapped river plume can be formed no matter how favorable the ambient conditions might be. The simulation results show properties of the river plume and the characteristics of flow and salinity within the estuary; they are completely consistent with the physics of estuaries and coastal oceans.

Conference Paper↗
USGS2004

Quantitative mineralogy of the Yukon River system: Changes with reach and season, and determining sediment provenance

The mineralogy of Yukon River basin sediment has been studied by quantitative X-ray diffraction. Bed, beach, bar, and suspended sediments were analyzed using the RockJock computer program. The bed sediments were collected from the main stem and from selected tributaries during a single trip down river, from Whitehorse to the Yukon River delta, during the summer of 2001. Beach and bar sediments were collected from the confluence region of the Tanana and Yukon Rivers during the summer of 2003. Suspended sediments were collected at three stations on the Yukon River and from a single station on the Tanana River at various times during the summers of 2001 through 2003, with the most complete set of samples collected during the summer of 2002. Changes in mineralogy of Yukon River bed sediments are related to sediment dilution or concentration effects from tributary sediment and to chemical weathering during transport. Carbonate minerals compose about 2 wt% of the bed sediments near Whitehorse, but increase to 14 wt% with the entry of the White River tributary above Dawson. Thereafter, the proportion of carbonate minerals decreases downstream to values of about 1 to 7 wt% near the mouth of the Yukon River. Quartz and feldspar contents of bed sediments vary greatly with the introduction of Pelly River and White River sediments, but thereafter either increase irregularly (quartz from 20 to about 50 wt%) or remain relatively constant (feldspar at about 35 wt%) with distance downstream. Clay mineral content increases irregularly downstream from about 15 to about 30 wt%. The chief clay mineral is chlorite, followed by illite + smectite; there is little to no kaolinite. The total organic carbon content of the bed sediments remains relatively constant with distance for the main stem (generally 1 to 2 wt%, with one exception), but fluctuates for the tributaries (1 to 6 wt%). The mineralogies of the suspended sediments and sediment flow data were used to calculate the amount of mineral dissolution during transport between Eagle and Pilot Station, a distance of over 2000 km. We estimate that approximately 3 wt% of the quartz, 15 wt% of the feldspar (1 wt% of the alkali and 25 wt% of the plagioclase), and 26 wt% of the carbonates (31 wt% of the calcite and 15 wt% of the dolomite) carried by the river dissolve in this reach. The mineralogies of the suspended sediments change with the season. For example, during the summer of 2002 the quartz content varied by 20 wt%, with a minimum in mid-summer. The calcite content varied by a similar amount, and had a maximum corresponding to the quartz minimum. These modes are related to the relative amount of sediment flowing from the White River system, which is relatively poor in quartz, but rich in carbonate minerals. Suspended total clay minerals varied by as much as 25 wt%, with maxima in mid July, and suspended feldspar varied up to 10 wt%. Suspended sediment data from the summers of 2001 and 2003 support the 2002 trends. A calculation technique was developed to determine theproportion of various sediment sources in a mixed sediment by unmixing its quantitative mineralogy. Results from this method indicate that at least three sediment sources can be identified quantitatively with good accuracy. With this technique, sediment mineralogies can be used to calculate the relative flux of sediment from different tributaries, thereby identifying sediment provenance.

American Mineralogist↗
USGS2008

PCDDs, PCDFs, PCBs, OC pesticides and mercury in fish and osprey eggs from Willamette River, Oregon (1993, 2001 and 2006) with calculated biomagnification factors

The osprey (Pandion haliaetus) population nesting along the main stem Willamette River and lower Santiam River was first studied to evaluate contaminants and reproductive rates in 1993 when 78 occupied nests were present. By 2001, the population increased to 234 occupied nests, a 13.7% annual rate of population increase. A sample egg was collected from each of a series of nests along the Upper River (river mile 55-187) in 1993, 2001 and 2006 to evaluate trends of persistent contaminants (organochlorine [OC] pesticides, polychlorinated biphenyls [PCBs], polychlorinated dibenzo-p-dioxins [PCDDs], and polychlorinated dibenzofurans [PCDFs]). Nearly all OC pesticide residues decreased significantly, e.g., p, p?-DDE (DDE) from 2,350 to 1,353 to 210 ??g/kg wet weight (ww). PCBs followed a similar pattern over time, e.g., ???PCBs 688 to 245 to 182 ??g/kg ww, while PCDDs and PCDFs showed a more precipitous decline (often 85-95%) between 1993 and 2001, with no egg analyses warranted in 2006. During 2001-2002, sample osprey eggs were also collected from nests at three Headwater Reservoirs and two lower reaches (Newberg Pool and Tidal Portland) of the Willamette River, as well as the lower portion of the Santiam River to evaluate spatial residue patterns. Significant differences were seldom detected among the different sampling areas for OC pesticides (probably due to small sample sizes), although higher concentrations were often seen in the lower reaches, e.g., DDE 901 ??g/kg ww (Headwater Reservoirs), 1,353 (Upper River), 1,384 (Newberg Pool) and 2,676 (Tidal Portland). PCB congener concentrations in eggs were usually higher in the Tidal Portland reach than at other locations and often significantly higher than at the Headwater Reservoirs or Upper River. Mercury (first analyzed in eggs in 2001), PCDDs and PCDFs were extremely low in 2001/2002 with no significant spatial patterns. Whole fish composite samples of largescale sucker (Catastomus macrocheilus) and northern pikeminnow (Ptychocheilus oregonensis), which account for about 90% of the biomass in the diet of this osprey population, were also collected from the Willamette River in 1993 and 2001 and analyzed for the same contaminants as osprey eggs. Contaminant residues in fish from the Upper River decreased between 1993 and 2001, paralleling findings for osprey eggs. Likewise, spatial patterns for fish residues paralleled findings for osprey eggs from the different reaches in 2001. A second empirical estimate of biomagnification factors (BMFs) from fish to osprey eggs for OC pesticides, PCBs, PCDDs and PCDFs (ww and lipid weight [lw] basis) was calculated based on residue data collected in 2001. The two independent BMF estimates (1993 and 2001) for each contaminant from the Upper River provide a measure of consistency, e.g., DDE (ww) 87 and 79, (lw) 103 and 112; ???PCBs (ww) 11 and 8.4, (lw) 13 and 12. Mercury did not biomagnify from fish to osprey eggs (BMF = 0.60). Legacy contaminants investigated had limited (perhaps only DDE), if any, effects on reproductive success of the increasing osprey population nesting along the Willamette River by 2001. ?? 2008 U.S. Government.

Ecotoxicology↗
USGS2005

Management scenarios for the Jordan River salinity crisis

Recent geochemical and hydrological findings show that the water quality of the base flow of the Lower Jordan River, between the Sea of Galilee and the Dead Sea, is dependent upon the ratio between surface water flow and groundwater discharge. Using water quality data, mass-balance calculations, and actual flow-rate measurements, possible management scenarios for the Lower Jordan River and their potential affects on its salinity are investigated. The predicted scenarios reveal that implementation of some elements of the Israel-Jordan peace treaty will have negative effects on the Jordan River water salinity. It is predicted that removal of sewage effluents dumped into the river (???13 MCM/a) will significantly reduce the river water's flow and increase the relative proportion of the saline groundwater flux into the river. Under this scenario, the Cl content of the river at its southern point (Abdalla Bridge) will rise to almost 7000 mg/L during the summer. In contrast, removal of all the saline water (16.5 MCM/a) that is artificially discharged into the Lower Jordan River will significantly reduce its Cl concentration, to levels of 650-2600 and 3000-3500 mg/L in the northern and southern areas of the Lower Jordan River, respectively. However, because the removal of either the sewage effluents or the saline water will decrease the river's discharge to a level that could potentially cause river desiccation during the summer months, other water sources must be allocated to preserve in-stream flow needs and hence the river's ecosystem. ?? 2005 Elsevier Ltd. All rights reserved.

Applied Geochemistry↗
USGS2023

Archaeological sites in Grand Canyon National Park along the Colorado River are eroding owing to six decades of Glen Canyon Dam operations

The archaeological record documenting human history in deserts is commonly concentrated along rivers in terraces or other landforms built by river sediment deposits. Today that record is at risk in many river valleys owing to human resource and infrastructure development activities, including the construction and operation of dams. We assessed the effects of the operations of Glen Canyon Dam – which, since its closure in 1963, has imposed drastic changes to flow, sediment supply and distribution, and riparian vegetation – on a population of 362 archaeological sites in the Colorado River corridor through Grand Canyon National Park, Arizona, USA. We leverage 50 years of evidence from aerial photographs and more than 30 years of field observations and measurements of archaeological-site topography and wind patterns to evaluate changes in the physical integrity of archaeological sites using two geomorphology-based site classification systems. We find that most archaeological sites are eroding; moreover, most are at increased risk of continuing to erode, due to six decades of operations of Glen Canyon Dam. Results show that the wind-driven (aeolian) supply of river-sourced sand, essential for covering archaeological sites and protecting them from erosion, has decreased for most sites since 1973 owing to effects of long-term dam operations on river sediment supply and riparian vegetation expansion on sandbars. Results show that the proportion of sites affected by erosion from gullies controlled by the local base-level of the Colorado River has increased since 2000. These changes to landscape processes affecting archaeological site integrity limit the ability of the National Park Service and Grand Canyon-affiliated Native American Tribes to achieve environmental management goals to maintain or improve site integrity in situ . We identify three environmental management opportunities that could be used to a greater extent to decrease the risk of erosion and increase the potential for in-situ preservation of archaeological sites. Environmental management opportunities are: 1) sediment-rich controlled river floods to increase the aeolian supply of river-sourced sand, 2) extended periods of low river flow to increase the aeolian supply of river-sourced sand, 3) the removal of riparian vegetation barriers to the aeolian transport of river-sourced sand.

Arizona↗
USGS2010

Source and fate of inorganic solutes in the Gibbon River, Yellowstone National Park, Wyoming, USA: I. Low-flow discharge and major solute chemistry

The Gibbon River in Yellowstone National Park (YNP) is an important natural resource and habitat for fisheries and wildlife. However, the Gibbon River differs from most other mountain rivers because its chemistry is affected by several geothermal sources including Norris Geyser Basin, Chocolate Pots, Gibbon Geyser Basin, Beryl Spring, and Terrace Spring. Norris Geyser Basin is one of the most dynamic geothermal areas in YNP, and the water discharging from Norris is much more acidic (pH 3) than other geothermal basins in the upper-Madison drainage (Gibbon and Firehole Rivers). Water samples and discharge data were obtained from the Gibbon River and its major tributaries near Norris Geyser Basin under the low-flow conditions of September 2006. Surface inflows from Norris Geyser Basin were sampled to identify point sources and to quantify solute loading to the Gibbon River. The source and fate of the major solutes (Ca, Mg, Na, K, SiO 2 , Cl, F, HCO 3 , SO 4 , NO 3 , and NH 4 ) in the Gibbon River were determined in this study and these results may provide an important link in understanding the health of the ecosystem and the behavior of many trace solutes. Norris Geyser Basin is the primary source of Na, K, Cl, SO 4 , and N loads (35–58%) in the Gibbon River. The largest source of HCO 3 and F is in the lower Gibbon River reach. Most of the Ca and Mg originate in the Gibbon River upstream from Norris Geyser Basin. All the major solutes behave conservatively except for NH 4 , which decreased substantially downstream from Gibbon Geyser Basin, and SiO 2 , small amounts of which precipitated on mixing of thermal drainage with the river. As much as 9–14% of the river discharge at the gage is from thermal flows during this period.

Wyoming↗
USGS2010

Persistent organic pollutants in fish tissue in the mid-continental great rivers of the United States

Great rivers of the central United States (Upper Mississippi, Missouri, and Ohio rivers) are valuable economic and cultural resources, yet until recently their ecological condition has not been well quantified. In 2004–2005, as part of the Environmental Monitoring and Assessment Program for Great River Ecosystems (EMAP-GRE), we measured legacy organochlorines (OCs) (pesticides and polychlorinated biphenyls, PCBs) and emerging compounds (polybrominated diphenyl ethers, PBDEs) in whole fish to estimate human and wildlife exposure risks from fish consumption. PCBs, PBDEs, chlordane, dieldrin and dichlorodiphenyltrichloroethane (DDT) were detected in most samples across all rivers, and hexachlorobenzene was detected in most Ohio River samples. Concentrations were highest in the Ohio River, followed by the Mississippi and Missouri Rivers, respectively. Dieldrin and PCBs posed the greatest risk to humans. Their concentrations exceeded human screening values for cancer risk in 27–54% and 16–98% of river km, respectively. Chlordane exceeded wildlife risk values for kingfisher in 11–96% of river km. PBDE concentrations were highest in large fish in the Missouri and Ohio Rivers (mean > 1000 ng g −1 lipid), with congener 47 most prevalent. OC and PBDE concentrations were positively related to fish size, lipid content, trophic guild, and proximity to urban areas. Contamination of fishes by OCs is widespread among great rivers, although exposure risks appear to be more localized and limited in scope. As an indicator of ecological condition, fish tissue contamination contributes to the overall assessment of great river ecosystems in the U.S.

Science of the Total Environment↗
USGS2023

Using cyanobacteria and other phytoplankton to assess trophic conditions: A qPCR-based, multi-year study in twelve large rivers across the United States

Phytoplankton is the essential primary producer in fresh surface water ecosystems. However, excessive phytoplankton growth due to eutrophication significantly threatens ecologic, economic, and public health. Therefore, phytoplankton identification and quantification are essential to understanding the productivity and health of freshwater ecosystems as well as the impacts of phytoplankton overgrowth (such as Cyanobacterial blooms) on public health. Microscopy is the gold standard for phytoplankton assessment but is time-consuming, has low throughput, and requires rich experience in phytoplankton morphology. Quantitative polymerase chain reaction (qPCR) is accurate and straightforward with high throughput. In addition, qPCR does not require expertise in phytoplankton morphology. Therefore, qPCR can be a useful alternative for molecular identification and enumeration of phytoplankton. Nonetheless, a comprehensive study is missing which evaluates and compares the feasibility of using qPCR and microscopy to assess phytoplankton in fresh water. This study 1) compared the performance of qPCR and microscopy in identifying and quantifying phytoplankton and 2) evaluated qPCR as a molecular tool to assess phytoplankton and indicate eutrophication. We assessed phytoplankton using both qPCR and microscopy in twelve large freshwater rivers across the United States from early summer to late fall in 2017, 2018, and 2019. qPCR- and microscope-based phytoplankton abundance had a significant positive linear correlation (adjusted R 2 = 0.836, p -value < 0.001). Phytoplankton abundance had limited temporal variation within each sampling season and over the three years studied. The sampling sites in the midcontinent rivers had higher phytoplankton abundance than those in the eastern and western rivers. For instance, the concentration (geometric mean) of Bacillariophyta, Cyanobacteria, Chlorophyta, and Dinoflagellates at the sampling sites in the midcontinent rivers was approximately three times that at the sampling sites in the western rivers and approximately 18 times that at the sampling sites in the eastern rivers. Welch's analysis of variance indicates that phytoplankton abundance at the sampling sites in the midcontinent rivers was significantly higher than that at the sampling sites in the eastern rivers ( p -value = 0.013) but was comparable to that at the sampling sites in the western rivers ( p -value = 0.095). The higher phytoplankton abundance at the sampling sites in the midcontinent rivers was presumably because these rivers were more eutrophic. Indeed, low phytoplankton abundance occurred in oligotrophic or low trophic sites, whereas eutrophic sites had greater phytoplankton abundance. This study demonstrates that qPCR-based phytoplankton abundance can be a useful numerical indicator of the trophic conditions and water quality in freshwater rivers.

Water Research↗
USGS1998

Partitioning and transport of total and methyl mercury in the Lower Fox River, Wisconsin

To investigate transport and partitioning processes of Hg(T) in the Fox River, we coupled detailed time series data of total mercury (Hg(T)) at the river mouth with transect sampling in the Lower Fox River. Unfiltered Hg(T) concentrations in the Fox River during the study period (April 1994-October 1995) ranged from 1.8 to 182 ng L(-1) with a median of 24.8 ng L-1, predominantly (93.6%) in the particulate phase. These levels were significantly elevated compared with other large tributaries to Lake Michigan (Hurley, J. P.; Shafer, M. M.; Cowell, S. E.; Overdier, J. T.; Hughes, P. E.; Armstrong, D. E. Environ. Sci. Technol. 1996, 30, 20932098). Transect sampling revealed progressively increasing water column Hg(T) concentrations and Hg(T) particulate enrichment downstream, which were consistent with trends in sediment Hg(T) levels in the river. Resuspended sediments are likely the predominant source of Hg from the Fox River into Green Bay. Despite elevated Hg(T) concentrations, methyl mercury (MeHg) concentrations were relatively low, suggesting limited bioavailability of Hg(T) associated with sediments.To investigate transport and partitioning processes of HgT in the Fox River, we coupled detailed time series data of total mercury (HgT) at the river mouth with transect sampling in the Lower Fox River. Unfiltered HgT concentrations in the Fox River during the study period (April 1994-October 1995) ranged from 1.8 to 182 ng L-1 with a median of 24.8 ng L-1, predominantly (93.6%) in the particulate phase. These levels were significantly elevated compared with other large tributaries to Lake Michigan. Transect sampling revealed progressively increasing water column HgT concentrations and HgT particulate enrichment downstream, which were consistent with trends in sediment HgT levels in the river. Resuspended sediments are likely the predominant source of Hg from the Fox River into Green Bay. Despite elevated HgT concentrations, methyl mercury (MeHg) concentrations were relatively low, suggesting limited bioavailability of HgT associated with sediments.

Environmental Science & Technology↗
USGS2006

Longitudinal hydraulic analysis of river‐aquifer exchanges

A longitudinal analysis of transient flow between a river and an underlying aquifer is developed to calculate flow rates between the river and the aquifer and the location of groundwater seepage into the river as it changes over time. Two flow domains are defined in the analysis: an upstream domain of fluvial recharge, where water flows vertically from the river into the unsaturated portion of the aquifer and horizontally in saturated parts of the aquifer, and a downstream domain of groundwater seepage to the river, where groundwater flows parallel to the underlying impermeable base. The river does not necessarily penetrate completely through the aquifer. A one‐dimensional, unsteady flow equation is derived from mass conservation, Darcy's law, and the geometry of the river‐aquifer system to calculate the water table position and the groundwater seepage rate into the river. Models based on numerical and analytical solutions of the flow equation were applied to a reach of the Methow River in north central Washington. The calibrated models simulated groundwater seepage with a root‐mean‐square error less than 5% of the mean groundwater seepage rates for three low‐flow evaluation periods. The analytical model provides a theoretical basis for a nonlinear exponential base flow recession generated by a draining aquifer, but not an explicit functional form for the recession. Unlike cross‐sectional approaches, the longitudinal approach allows the analysis of the length and location of groundwater seepage to a river, which have important ecological implications in many rivers. In the numerical simulations, the length of the groundwater seepage varied seasonally by about 4 km and the upstream boundary of groundwater seepage was within 689 m of its location at a stream gage on 9 September 2001 and within 91 m of its location on 6 October 2002. To demonstrate its utility in ecological applications, the numerical model was used to calculate differences in length of groundwater seepage to the Methow River under an early runoff scenario and the timing of those differences with respect to life stages of chinook salmon.

Water Resources Research↗
USGS2017

Spatial and temporal genetic analysis of Walleyes in the Ohio River

Previous genetic analyses have shown that Walleyes Sander vitreus in the upper Ohio River comprise two distinct genetic strains: (1) fish of Great Lakes origin that were stocked into the Ohio River basin and (2) a remnant native strain (Highlands strain). Resource agencies are developing management strategies to conserve and restore the native strain within the upper reaches of the Ohio River. Hybridization between strains has impacted the genetic integrity of the native strain. To better understand the extent and effects of hybridization on the native strain, we used mitochondrial DNA and microsatellite markers to evaluate the spatial (river sections) and temporal (pre- and poststocking) genetic diversity of Ohio River Walleyes. Contemporary Lake Erie Walleyes and archival museum specimens collected from the Ohio River basin were used for comparison to contemporary Ohio River samples. Although there was evidence of hybridization between strains, most of the genetic diversity within the Ohio River was partitioned by basin of origin (Great Lakes versus the Ohio River), with greater similarity among river sections than between strains within the same section. Results also suggested that the native strain has diverged from historical populations. Furthermore, notable decreases in measures of genetic diversity and increased relatedness among native-strain Walleyes within two sections of the Ohio River may be related to stocking aimed at restoration of the Highlands strain. Our results suggest that although the Highlands strain persists within the Ohio River, it has diverged over time, and managers should consider the potential impacts of future management practices on the genetic diversity of this native strain.

Ohio River↗
USGS2019

A multidisciplinary framework to derive global river reach classifications at high spatial resolution

Projected climate and environmental change are expected to increase the pressure on global freshwater resources. To prepare for and cope with the related risks, stakeholders need to devise plans for sustainable management of river systems, which in turn requires the identification of management-appropriate operational units, such as groups of rivers that share similar environmental and biological characteristics. Ideally, these units are of a manageable size, and are biotically or abiotically distinguishable across a variety of river types. Here, we aim to address this need by presenting a new global river classification framework (GloRiC) to establish a common vocabulary and standardized approach to the development of globally comprehensive and integrated river classifications that can be tailored to different goals and requirements. We define the GloRiC conceptual framework based on five categories of variables: (1) hydrology; (2) physiography and climate; (3) fluvial geomorphology; (4) water chemistry; and (5) aquatic biology. We then apply the framework using hydro-environmental attributes provided by a seamless high-resolution river reach database to create initial instances of three sub-classifications (hydrologic, physio-climatic, and geomorphic) which we ultimately combine into 127 river reach types at the global scale. These supervised classifications utilize a mix of statistical analyses and expert interpretation to identify the classifier variables, the number of classes, and their thresholds. In addition, we also present an unsupervised, multivariable k-means statistical clustering of all river reaches into 30 groups. These first-of-their-kind global river reach classifications at high spatial resolution provide baseline information for a total of 35.9 million kilometers of rivers that have been assessed in this study, and are expected to be particularly useful in remote or data-poor river basins. The GloRiC framework and associated data are primarily designed for broad and rapid applicability in assessments that require stratified analyses of river ecosystem conditions at global and regional scales; smaller-scale applications could follow the same conceptual framework yet use more detailed data sources.

Environmental Research Letters↗
USGS2020

Characterization of pallid sturgeon (Scaphirhynchus albus) spawning habitat in the Lower Missouri River

Acipenseriformes (sturgeons and paddlefish) globally have declined throughout their range due to river fragmentation, habitat loss, overfishing, and degradation of water quality. In North America, pallid sturgeon (Scaphirhynchus albus) populations have experienced poor to no recruitment, or substantial levels of hybridization with the closely related shovelnose sturgeon (S. platorynchus). The Lower Missouri River is the only portion of the species’ range where successful reproduction and recruitment of genetically pure pallid sturgeon have been documented. This paper documents spawning habitat and behavior on the Lower Missouri River, which comprises over 1,300 km of unfragmented river habitat. The objective of this study was to determine spawning locations and describe habitat characteristics and environmental conditions (depth, water velocity, substrate, discharge, temperature, and turbidity) on the Lower Missouri River. We measured habitat characteristics for spawning events of ten telemetry‐tagged female pallid sturgeon from 2008–2013 that occurred in discrete reaches distributed over hundreds of kilometers. These results show pallid sturgeon select deep and fast areas in or near the navigation channel along outside revetted banks for spawning. These habitats are deeper and faster than nearby river habitats within the surrounding river reach. Spawning patches have a mean depth of 6.6 m and a mean depth‐averaged water‐column velocity of 1.4 m per second. Substrates in spawning patches consist of coarse bank revetment, gravel, sand, and bedrock. Results indicate habitat used by pallid sturgeon for spawning is more common and widespread in the present‐day channelized Lower Missouri River relative to the sparse and disperse coarse substrates available prior to channelization. Understanding the spawning habitats currently utilized on the Lower Missouri River and if they are functioning properly is important for improving habitat remediation measures aimed at increasing reproductive success. Recovery efforts for pallid sturgeon on the Missouri River, if successful, can provide guidance to sturgeon recovery on other river systems; particularly large, regulated, and channelized rivers.

Missouri, Nebraska, Wyoming, Montana, North Dakota↗
USGS2021

Major reorganization of the Snake River modulated by passage of the Yellowstone Hotspot

The details and mechanisms for Neogene river reorganization in the U.S. Pacific Northwest and northern Rocky Mountains have been debated for over a century with key implications for how tectonic and volcanic systems modulate topographic development. To evaluate paleo-drainage networks, we produced an expansive data set and provenance analysis of detrital zircon U-Pb ages from Miocene to Pleistocene fluvial strata along proposed proto-Snake and Columbia River pathways. Statistical comparisons of Miocene-Pliocene detrital zircon spectra do not support previously hypothesized drainage routes of the Snake River. We use detrital zircon unmixing models to test prior Snake River routes against a newly hypothesized route, in which the Snake River circumnavigated the northern Rocky Mountains and entered the Columbia Basin from the northeast prior to incision of Hells Canyon. Our proposed ancestral Snake River route best matches detrital zircon age spectra throughout the region. Furthermore, this northerly Snake River route satisfies and provides context for shifts in the sedimentology and fish faunal assemblages of the western Snake River Plain and Columbia Basin through Miocene−Pliocene time. We posit that eastward migration of the Yellowstone Hotspot and its effect on thermally induced buoyancy and topographic uplift, coupled with volcanic densification of the eastern Snake River Plain lithosphere, are the primary mechanisms for drainage reorganization and that the eastern and western Snake River Plain were isolated from one another until the early Pliocene. Following this basin integration, the substantial increase in drainage area to the western Snake River Plain likely overtopped a bedrock threshold that previously contained Lake Idaho, which led to incision of Hells Canyon and establishment of the modern Snake and Columbia River drainage network.

Alberta, British Columbia, Idaho, Montana, Oregon,↗