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USGS2021

Characterization of historical and stochastically generated climate and streamflow conditions in the Souris River Basin, United States and Canada

The Souris River Basin is a 61,000-square-kilometer basin in the Provinces of Saskatchewan and Manitoba in Canada and the State of North Dakota in the United States. Greater than average snowpack during the winter of 2010–11, along with record-setting rains in May and June 2011, resulted in historically unprecedented flooding in the Souris River Basin. The severity of the 2011 flood led the United States and Canada to request a review of the operating plan for any improvements of reservoir operations and flood control measures in the basin, and the Souris River Basin Task Force was formed. The International Souris River Study Board was then formed in 2017 to carry out the recommendations of the Souris River Basin Task Force laid out in a plan of study. To support the International Souris River Study Board, the U.S. Geological Survey (USGS), in cooperation with the North Dakota State Water Commission and the International Joint Commission, used the previously developed unregulated and regulated streamflow models and data for stochastic streamflow in the Souris River Basin to characterize climate and streamflow and support selection of streamflow traces based on their characterization. Components of the original stochastic hydrology models and their outputs were used in this phase of the study to (1) characterize historical and stochastic climate and streamflow for the Souris River Basin, (2) disaggregate monthly stochastic streamflow spatially and temporally to meet the needs of the U.S. Army Corps of Engineers, Hydrologic Engineering Center, Reservoir System Simulation model for the Souris River Basin, and (3) discuss selection of disaggregated streamflow traces (simulations) using the characteristics of climate and streamflow. A trace is a time series of a stochastic variable such as streamflow, potential evapotranspiration, or precipitation. To characterize climate conditions, precipitation, potential evapotranspiration (PET), and moisture deficit for the Souris River Basin and individual points at Rafferty, Grant Devine, and Lake Darling Reservoirs were determined annually and seasonally. The annual basin (November 1–October 31) precipitation for the 50-percent nonexceedance probability is 452 millimeters (mm). Spring (March–May) is the wettest season, followed by summer (June–August), fall (September–November), and winter (December–February). Annual moisture deficit was largest at Lake Darling Reservoir, followed by Rafferty Reservoir, and then Grant Devine Reservoir. Annual maximum monthly mean streamflow was determined for the Souris River below Rafferty Reservoir, Saskatchewan (Canadian streamgage 05NB036); Long Creek near Noonan (above Boundary Reservoir), North Dakota (USGS streamgage 05113600); Moose Mountain Creek near Oxbow, Saskatchewan (Canadian streamgage 05ND004); the Souris River near Sherwood, N. Dak. (USGS streamgage 05114000); the Des Lacs River at Foxholm, N. Dak. (USGS streamgage 05116500); and the Souris River above Minot, N. Dak. (USGS streamgage 05117500). When the seasonal maximum monthly mean streamflows are evaluated in contrast to annual maximum monthly mean streamflows separated by their seasonal occurrence, summer months of annual maximum monthly mean streamflows have a higher 50-percent exceedance probability of streamflow compared to annual maximum monthly mean streamflows that occur in spring, seasonal maximum monthly mean streamflows that occur in spring, and seasonal maximum monthly mean streamflows that occur in summer. When annual maximum monthly mean streamflows in summer are compared to annual maximum monthly mean streamflows in spring, they are consistently higher in streamflow but occur in less than 4.2 percent of years. Evaluation of whether the annual maximum monthly mean streamflows that occur in summer can be described as a separate population from annual maximum monthly mean streamflows that occur in spring was outside the scope of this study, and the summer and spring annual maximum monthly mean streamflows were not tested for statistical differences in mean or variance. Further investigation of seasonal weather patterns that induce flooding could lead to a better understanding of the seasonal differences in flooding. Long-term hydrologic drought was characterized by evaluating multiyear mean streamflow. Shorter averaging periods have greater streamflow variability than longer periods and hence have a wider range of values. As the averaging period is extended to a longer period, the variability of mean streamflow decreases, and the more extreme streamflow volumes seen in shorter averaging periods cannot be sustained. Stochastic streamflow time series were disaggregated spatially and temporally for use in a HEC–ResSim model. The combination of monthly and daily stochastic streamflow data was used to select traces with qualities that could be used to test alternatives focused on water supply, summer flooding, and apportionment.

Manitoba, North Dakota, Saskatchewan↗

USGS2021

Historical floods and geomorphic change in the lower Little Colorado River during the late 19th to early 21st centuries

The Little Colorado River is a major tributary to the Colorado River with a confluence at the boundary between Marble and Grand Canyons within Grand Canyon National Park, Arizona. The bedrock gorge of the lower Little Colorado River is home to the largest known population of Gila cypha (humpback chub), an endangered fish endemic to the Colorado River Basin. Channel conditions might affect the spawning success of the humpback chub. Perennial base flow in the lower Little Colorado River deposits travertine, which forms dams and cascades. Geomorphic change in the lower Little Colorado River is controlled by the growth and collapse of travertine dams, debris flows from tributaries, and reworking of dams and debris fans by Little Colorado River floods. A study was conducted by the U.S. Geological Survey, in cooperation with the Glen Canyon Dam Adaptive Management Program and the U.S. Fish and Wildlife Service, to document historical floods and geomorphic change in the lower Little Colorado River. For this study, we used historical and gaging records and hydraulic modeling of surveyed high-water marks from historical Little Colorado River floods to construct a peak-flow history of the lower Little Colorado River. We analyzed base-flow longitudinal profiles and historical photographs to determine changes in the longitudinal profile of the lower Little Colorado River from 1909 to 2019. The peak-flow magnitudes and the frequency of larger floods have declined since the late 1800s, and the longitudinal profile of the Little Colorado River has substantially changed between 1909 and 2019. Aggradation of as much as 6 meters in some reaches occurred between 1926 and 1992, mostly before the 1950s. This aggradation was caused largely by the documented growth of travertine dams continuing through at least 2013 at several locations. Other reaches were incised by as much as 10 meters between 1926 and 1992, but mostly before the 1950s, largely from the breaching of travertine dams. Travertine dams in the Little Colorado River have survived large flooding events and then later collapsed during floods of lower streamflow or even periods of base flow. The decline in peak-flow magnitude and frequency has changed the dominant geomorphic processes in this formerly dynamic reach. Large incision events have not been documented since the early 1950s; for this reason, the reach has only aggraded or remained stable since that time. This loss of geomorphic disturbance has likely affected, and will likely continue to affect, the spawning habitat of the endangered humpback chub in the lower Little Colorado River.

Arizona, Utah, New Mexico, Utah↗

USGS2023

Long-term water-quality constituent trends in the Little Arkansas River, south-central Kansas, 1995–2021

The Equus Beds aquifer and Cheney Reservoir are primary sources for the city of Wichita’s current (2023) water supply. The Equus Beds aquifer storage and recovery (ASR) project was developed by the city of Wichita in the early 1990s to meet future water demands using the Little Arkansas River as an artificial aquifer recharge water source during above-base-flow conditions. Little Arkansas River water is removed from the river at an ASR Facility intake structure, treated using National Primary Drinking Water Regulations as a guideline, and is infiltrated into the Equus Beds aquifer through recharge basins or injected into the aquifer through recharge wells for later use. The U.S. Geological Survey, in cooperation with the city of Wichita, completed this study to quantify and characterize Little Arkansas River water-quality data. Data in this report can be used to evaluate changing conditions, provide science-based information for decision making, and help meet regulatory requirements. Continuous (hourly) physicochemical properties were measured, and discrete water-quality samples were collected from three Little Arkansas River sites located along the easternmost extent of the Equus Beds aquifer during 1995 through 2021 over a range of streamflow conditions. The Little Arkansas River at Highway 50 near Halstead, Kansas, streamgage (U.S. Geological Survey station 07143672; hereafter referred to as the “Highway 50 site”) is located upstream from the other two sites, and the Little Arkansas River near Sedgwick, Kans., streamgage (U.S. Geological Survey station 07144100; hereafter referred to as the “Sedgwick site”) is located downstream from the other two sites; these two sites bracket most of the easternmost part of the Equus Beds aquifer. The Little Arkansas River upstream of ASR Facility near Sedgwick, Kans., streamgage (U.S. Geological Survey station 375350097262800; hereafter referred to as the “Upstream ASR site”) is located between the Highway 50 and Sedgwick sites, about 14.7 river miles (mi) downstream from the Highway 50 site, about 1.7 river mi upstream from the Sedgwick site, and immediately upstream from the ASR Facility intake structure. Surrogate models for water-quality constituents of interest (including bromide, dissolved organic carbon, 2-chloro-4-isopropylamino-6-amino- s -triazine [deethylatrazine], atrazine, and metolachlor) were updated or developed using continuously measured and concomitant discrete data. These surrogate models, along with previously developed regression models, were used to compute concentrations (at the Highway 50, Sedgwick, and Upstream ASR sites) and loads (at the Highway 50 and Sedgwick sites) during the study period. Federal criteria were used to evaluate water quality. Where applicable, water-quality data were compared to Federal national drinking-water regulations. Flow-normalized water-quality constituent trends were evaluated using Weighted Regressions on Time, Discharge, and Season (WRTDS) statistical models and water-quality trends were described using WRTDS bootstrap tests. Continuously computed primary ion concentrations were generally larger at the Highway 50 site compared to the Sedgwick site. During the study period, the Federal secondary maximum contaminant level (SMCL) for dissolved solids was exceeded 57 percent of the time at the Highway 50 site and 38 percent of the time at the Sedgwick site. Computed bromide concentrations were larger at the Highway 50 site and exceeded the city of Wichita treatment threshold about 70, 21, and 19 percent of the time at the Highway 50, Sedgwick, and Upstream ASR sites, respectively. Chloride concentrations exceeded the Federal SMCL about 16 percent of the time at the Highway 50 site and did not exceed the SMCL at the Sedgwick site. Continuous arsenic concentrations exceeded the Federal Maximum Contaminant Level (MCL) 9 to 15 percent of the time at the Sedgwick and Highway 50 sites, respectively, during the study. Atrazine concentrations exceeded the Federal MCL 10 percent of the time at the Highway 50 and Sedgwick sites and 14 percent of the time at the Upstream ASR site during the study; computed glyphosate concentrations at the Sedgwick site never exceeded the MCL during the study. Little Arkansas River flow-normalized primary ion concentrations during 1995 through 2021 generally had downward trends and decreases were generally larger at the Highway 50 site compared to the Sedgwick site. Dissolved solids and chloride concentrations decreased at the Highway 50 and Sedgwick sites. Bromide had no trend at the Highway 50 site and a downward trend at the Sedgwick site. Nitrate plus nitrite and total phosphorus concentrations had upward trends at the Highway 50 site but downward trends at the Sedgwick site, whereas total organic carbon had upward trends at both sites. Nitrate plus nitrite, total nitrogen, total phosphorus, and total organic carbon fluxes had upward trends at the Highway 50 and Sedgwick sites. Suspended-sediment concentrations had an upward trend at the Highway 50 site and had no trend at the Sedgwick site. Arsenic concentrations had downward trends at the Highway 50 and Sedgwick sites. About one-quarter to one-half of the Little Arkansas River loads, including nutrients and sediment, were transported during 1 percent of the time during the study. Because streamflows are highly sensitive to climatic variation and an increase of extreme precipitation events in the Great Plains is expected, similar disproportionately large pollutant loading events may increase into the future. Continuous measurement of physicochemical properties in near-real time allowed characterization of Little Arkansas River surface water during conditions and time scales that would not have been possible otherwise and served as a complement to discrete water-quality sampling. Continuation of this water-quality monitoring will provide data to characterize changing conditions in the Little Arkansas River and possibly identify new and changing trends. Information in this report allows the city of Wichita to make informed municipal water-supply decisions using past and present water-quality conditions and trends in the watershed.

Kansas↗

USGS2023

Groundwater discharge by evapotranspiration from the Amargosa Wild and Scenic River and contributing areas, Inyo and San Bernardino Counties, California

The Amargosa Wild and Scenic River, located in the southwestern Mojave Desert in Inyo and San Bernardino Counties, California, is a Federally protected waterway that supports the biodiversity of the region. Water in the river primarily comes from interbasin groundwater flow that originates as precipitation in the Spring Mountains. The precipitation enters the regional groundwater system and flows westerly beneath Pahrump, Chicago, and California Valleys before discharging into the Amargosa Wild and Scenic River system. In Pahrump Valley, groundwater discharge occurs as evapotranspiration (ET), spring discharge, and groundwater pumping, and in Chicago and California Valleys, groundwater discharge occurs as ET and spring discharge. Remaining groundwater flows into the Amargosa Wild and Scenic River and its main tributary, the China Ranch Wash, or is discharged from regional springs downgradient from Chicago and California Valleys. The Amargosa Wild and Scenic River and the China Ranch Wash sustain areas of deep-rooted vegetation (phreatophytes) that consume regional groundwater. Discharge from regional springs in the area only flows on the land surface for short distances before seeping back into the ground where the water generally is consumed by evaporation from moist soil or by transpiration of plants. Intermittent Amargosa River flow out of the study area is the only other form of discharge. In arid regions such as the Mojave Desert, groundwater discharge by evapotranspiration (ET g ) often is the only significant form of discharge in a regional water budget, and therefore, an estimate of annual ET g is a good approximation of the total annual groundwater discharge. In this study area, however, total annual discharge is annual ET g plus the annual surface-water discharge of the Amargosa River that exits the study area. Therefore, the annual ET g from Chicago and California Valleys and along the Amargosa Wild and Scenic River and the China Ranch Wash, plus the discharge of the Amargosa River, is a good approximation of the total annual groundwater discharge required to sustain the riparian habitats and surface-water flow in the Amargosa Wild and Scenic River. The Amargosa Conservancy and Inyo County, Calif., are interested in quantifying the total annual groundwater discharge required to sustain the riparian habitats and surface-water flow in the Amargosa Wild and Scenic River and entered into a cooperative agreement with the U.S. Geological Survey to estimate ET g from the Amargosa Wild and Scenic River study area. The study area consists of open-water bodies, areas with perennially moist soil, and areas with phreatophytes, all of which are discharging regional groundwater in Chicago and California Valleys, along the Amargosa Wild and Scenic River, and in the China Ranch Wash. Annual ET g for the Amargosa Wild and Scenic River study area is estimated to be 10,139,000 cubic meters. The estimate was determined by delineating boundaries of open water, perennially moist soil, and phreatophytes, multiplying the areas by appropriate site-scale ET g to derive annual ET g for each ET unit, and then adding the annual ET g for all ET units in the GDAs and study area. Boundaries of discharge areas were visually delineated using high-resolution aerial imagery and refined by field verification. Open water and moist soil ET g were estimated in previous investigations, and phreatophyte ETg was estimated from a quadratic relation between site-scale ET g and a vegetation index of the study area. The quadratic relation was derived from four points. Two points were based on the site-scale ET g estimated for this study and two points corresponded to theoretical minimum and maximum points. Site-scale ET g was measured at two ET-monitoring sites using the eddy-covariance method. At one site, located in sparse shrubs, ET g was 0.121 meters per year, and at the other site, located in dense wetland vegetation, ET g was 1.056 meters per year. A scaled normalized difference vegetation index (NDVI) that encompasses the study area was created from 0.6-meter resolution multispectral (4-band) aerial imagery from 2020 and was used as an indicator of plant density or cover.

California↗

USGS2024

Reservoir evolution, downstream sediment transport, downstream channel change, and synthesis of geomorphic responses of Fall Creek and Middle Fork Willamette River to water years 2012–18 streambed drawdowns at Fall Creek Lake, Oregon

Executive Summary Chapter A. Introduction Fall Creek Dam impounds Fall Creek Lake, a 10-kilometer-long reservoir in western Oregon and is operated by the U.S. Army Corps of Engineers (USACE) primarily for flood-risk management (or flood control) in late autumn through early spring months, as well as for water quality, irrigation, recreation, and habitat in late spring through early autumn. Since 2011 (water year [WY] 2012), Fall Creek Lake has been temporarily drawn down each year to facilitate downstream passage of juvenile spring Chinook salmon ( Oncorhynchus tshawytscha ) through the 55-meter (m) high dam. This annual dam operation is temporary, typically lasting about 1–2 weeks from WY 2012 through 2020 (drawdown operations in WY 2022–24 have increased to more than 6 weeks). Drawdown of the reservoir results in lake levels being lowered to the elevation near the historical, pre-dam streambed. The annual streambed drawdowns of WY 2012–18 have improved fish passage and led the USACE to formally adopt streambed drawdowns as part of annual operations at Fall Creek Dam. However, temporarily lowering the lake to streambed creates free-flowing conditions in the reservoir that result in the erosion and episodic export of predominantly sand and finer-grained sediments (less than 2 millimeters [mm]) to the lower gravel-bed reaches of Fall Creek and the Middle Fork Willamette River. The introduction of large volumes of sand and finer-grain sediment into the dam-regulated reaches downstream from Fall Creek Dam prompted questions about the geomorphic responses to annual streambed drawdowns within Fall Creek Lake and downstream reaches along Fall Creek and the Middle Fork Willamette River. The U.S. Geological Survey (USGS) in partnership with USACE initiated a comprehensive geomorphic and sediment transport investigation to assess the coupled processes of reservoir erosion, sediment evacuation from Fall Creek Lake, and patterns of sediment transport and deposition in reaches downstream from the Fall Creek Dam that have resulted from annual streambed drawdowns. The purpose of this report is to systematically describe the processes of sediment erosion, transport, and deposition at Fall Creek Lake and geomorphic interactions between reaches upstream and downstream from Fall Creek Dam that relate to dam operations. Specifically, this report focuses on evaluating geomorphic responses to streambed drawdowns from WY 2012 through 2018 and placing drawdown-induced geomorphic responses within the broader context of physiographic and historical conditions and dam operations of Fall Creek and Middle Fork Willamette Rivers. Key objectives for this study were to characterize changes in reservoir morphology and substrate at Fall Creek Lake, describe the character and temporal pattern of sediment transport downstream from Fall Creek Dam, characterize geomorphic changes in channel reaches downstream from the Fall Creek Dam, and relate these data to the annual streambed drawdowns of WY 2012–18. This study uses multiple independent monitoring and measurement approaches to assess site, reach, and river-scale geomorphic responses to drawdowns to inform dam and reservoir management. Patterns and processes of reservoir evolution were assessed with geomorphic mapping and volumetric analyses of topography through comparison of multiple digital surface models (DSMs). Just downstream from Fall Creek Dam, analyses of sediment export from the reservoir focused on suspended sediment but also incorporated bedload analyses to assess sediment sizes. Geomorphic assessments downstream from the dam used reach-scale and site-scale approaches to document changes in channel morphology and substrate, including site measurements of sand and finer-grained sediment deposition and in-channel bed-material, volumetric change analyses from comparison of digital elevation models (DEMs), and repeat geomorphic mapping. Findings from this study inform river management and dam operations by providing an understanding of (1) coupled upstream-downstream geomorphic responses to the Fall Creek Lake streambed drawdowns, (2) geomorphic responses of Fall Creek Lake streambed drawdowns in comparison to drawdowns at other large dams, (3) controls on reservoir erosion and downstream geomorphic responses, and (4) implications for future hydrogeomorphic changes that may result from continued drawdowns and monitoring activities to assess those changes. Chapter B. Reservoir Morphology and Evolution Related to Dam Operations at Fall Creek Lake To understand the volume and distribution of sediment accumulation in Fall Creek Lake since dam closure in 1965, decadal-scale sedimentation patterns (spanning approximately 1965–2016) are evaluated using a combination of storage curve analyses and geomorphic mapping. Short-term (drawdown event-scale) patterns of erosion, sedimentation, and sediment export downstream are evaluated using a combination of geomorphic mapping and change detection analyses that quantify the distribution and total volume of sediment erosion and deposition within Fall Creek Lake. Geomorphic mapping of reservoir topography and analyses of historical datasets reveals four categories of landforms and sediment processes within Fall Creek Lake related to lake level operations: lacustrine sedimentation expressed in the reservoir floor, fluvial erosion and deposition within historical stream channels during streambed drawdowns, channel-like features created by erosion within the reservoir floor during streambed drawdowns, and erosion on reservoir hillslopes. Where the reservoir floor is mapped for this study as pelagic (deep water), deposition up to 3 meters (m) thick by lacustrine processes and burial of pre-dam topography with deposits thinning toward the edges of the valley floor and upstream areas of reservoir are observed. Despite over 50 years of sediment accumulation since dam construction, the main stream channels of Fall and Winberry Creeks (or reservoir thalwegs) through the reservoir are well defined, though their distinct morphology is likely influenced by a long history of recurring historical drawdowns to or near streambed since dam construction. Unregulated streamflow and sediment transport through the reservoir primarily are confined to these channels during the streambed drawdown periods. Erosional channel-like features created by drawdowns are carved through underlying, unconsolidated reservoir floor sediments and are most prominent in the lower reservoir below minimum conservation pool (the low pool elevation during winter flood season); sediment generated from the formation of these drawdown channels is more likely to be transported through and out of the reservoir than sediment deposits along the reservoir hillslopes at the valley margins that are separated from main channels by areas of low-gradient reservoir floor. Morphologic changes in the lower reservoir topography between January 2012 and November 2016 indicate overall net erosion of about 129,500 cubic meters (m 3 ). The most prominent geomorphic changes occurred along the main channels of Fall and Winberry Creeks near the Fall Creek Dam where incision, lateral migration, and slumping banks resulted in vertical and lateral adjustments to channel position, whereas most changes fell below the detectable limit on higher-elevation reservoir floor surfaces except where erosion occurred along features mapped as drawdown channels. Chapter C. Sediment Delivery from Fall Creek Lake and Transport through Downstream Reaches USGS implemented a sediment monitoring program in WY 2013–18 to evaluate the quantity and character of reservoir sediment exported from Fall Creek Lake during streambed drawdowns. Turbidity and suspended sediments were monitored annually autumn through spring to span the WY 2013–18 streambed drawdowns; however, unequal monitoring timeframes each year reduced the ability to compare results and factors affecting sediment export from the reservoir difficult between years. These data were originally measured to develop regressions and compute suspended-sediment loads (SSL). Bedload sediment monitoring from a cableway at the Fall Creek streamgage was completed in the autumn-winter of WY 2013 and 2017. The limited number of samples and presumed variability in sediment supply from the reservoir precluded construction of streamflow and bedload discharge relations to compute more than instantaneous bedload. Sand and finer-grained silts and clays were transported from the reservoir in suspension, though some coarser grains (up to 32 mm) were also mobilized and transported downstream from the dam as bedload. Observations of increased sediment transport downstream from Fall Creek Dam coincided with lake levels approaching about 3 m (10 feet [ft] or elevation 690 ft) above the streambed regulating outlets. Suspended-sediment loads computed for the full monitoring periods WY 2013–18 at the Fall Creek streamgage, located 1.4 kilometers (km) downstream from Fall Creek Dam, range from 54,700 metric tons (t) in WY 2013 to 13,900 t in WY 2018. Although the total annual SSL varied from year to year, the overall seasonal patterns of suspended sediment transport throughout each year were similar during monitoring in WY 2013-18. Suspended-sediment loads were low prior to the drawdown, then increased rapidly as lake levels lowered and approached the streambed. In the weeks following the drawdown period, as pool levels were increased, SSL remained slightly elevated above pre-drawdown levels but generally declined through the following winter and spring except during streamflow-driven pulses of suspended-sediment transport. WY 2013 had the greatest total computed SSL for each streambed drawdown and partial-year monitoring period. SSL computed for the partial-year period have generally decreased since WY 2013 and have varied by about 6,800 t with the exception of WY 2014. WY 2014 SSL reflects anomalously low sediment export due to low streamflows and freezing conditions that stabilized reservoir floor deposits. Bedload measurements in the short 1.4-km reach between Fall Creek Dam and the Fall Creek streamgage showed an inverse correlation between bedload transport rates and discharge, which probably reflects diminishing supply of coarse-sized sediment. Sand was more abundant (60–100 percent) than gravel in bedload samples confirming sand and finer-grained sediment dominated sediment evacuated from the reservoir during streambed drawdowns at Fall Creek Lake. Chapter D. Geomorphic Responses to Fall Creek Lake Streambed Drawdowns Downstream from Fall Creek Dam In the days, weeks, and months following streambed drawdown operations at Fall Creek Dam through WY 2018, sites downstream from the dam displayed a variety of geomorphic responses to reservoir sediment delivery within the main channel and overbank areas. Evaluation of streambed elevations at two streamgages located 1.4 km downstream from the dam on Fall Creek and 16.3 km downstream from the dam on the Middle Fork Willamette River indicated the effects of drawdown sediment on bed elevations were modest and transient. Repeat particle size measurements (October 2015 and September 2016) at five sites along Fall Creek and the Middle Fork Willamette River showed similar grain-sized distributions that do not reveal substantial deposition of fine-grained sediment related to the WY 2016 streambed drawdown. Altogether, these findings indicate that transport capacity in the main, low-flow channels of Fall Creek and Middle Fork Willamette River during WY 2012–18 was sufficient to mobilize and evacuate reservoir sediments from streambed drawdowns or other bank material and tributary sources. However, other monitoring for this study indicate low-velocity zones in off-channel areas are prime locations for sand and finer-grain sediment deposition. Patterns of overbank sediment accumulation indicate that the magnitude and timing of overbank deposition on bars and low-elevation floodplain varies with proximity to the dam, geomorphic setting, streamflows, and other factors. Sand and finer-grained reservoir sediments carried as suspended-sediment load in the reaches downstream from Fall Creek Dam were deposited in overbank areas as observed with clay-horizon markers during WY 2016–17. Overbank deposition quantified with Geomorphic Change Detection (GCD) software evaluated landform-scale patterns of erosion and deposition using repeat light detection and ranging (lidar) surveys at two sites in the Upper Fall Creek reach and one site in the Jasper reach for 3 years (2012–15) and one site in the Clearwater reach for 6 years (2009–15). Deposition thickness and spatial patterns from the GCD analysis were variable; some sites had dispersed but measurable deposition while at others, deposition was highly localized and exceeded 1 m in depth. Patterns of overbank deposition illustrate interactions among bar morphology, local hydraulics, and suspended-sediment transport dynamics that can create patches of highly localized deposition. The measured deposition at the two Fall Creek GCD sites likely resulted from reservoir sediments released from Fall Creek Lake during streambed drawdowns in WY 2016 and 2017 because the limited sediment inputs from bank material (geomorphically laterally stable reach) or tributaries (no significant tributaries) provided few other sediment sources. On the Middle Fork Willamette River, observed patterns of overbank deposition could reflect sediment sourced from upstream tributaries, bank erosion, or Fall Creek Lake streambed drawdown operations. Despite the introduction of several thousand tons of reservoir sediment delivered from the Fall Creek Lake streambed drawdowns to below-dam river corridors, reach-scale mapping of channel features downstream from Fall Creek Dam shows minimal evidence of changes in channel planform or landforms that can be attributed to a drawdowns in WY 2012–16. On Upper Fall Creek reach, widespread increases in gravel bars or other in-channel sediment did not result from the five streambed drawdowns. The main changes attributable to sediment releases from Fall Creek Lake were localized increases in vegetated bar area, particularly on channel margin areas where sand and finer-grain sediment was deposited and rapidly colonized by vegetation. The area of mapped secondary water features decreased between 2005 and 2016, but that may be due to lower discharges depicted in the 2016 aerial photographs and less mapped area of inundation. Primary changes along the Lower Fall Creek reach include a 6.4 percent decrease in area of secondary water features between 2011 and 2016, and a nearly twofold increase in the area of unvegetated bars. Immediately downstream from the Fall Creek confluence, there were negligible changes in the location and areas of vegetated bars and the main wetted channel between 2005 and 2016, and local increases in bar area cannot be attributed solely to deposition of reservoir sediments from Fall Creek Lake because (1) areas along the Middle Fork Willamette River just upstream from the Fall Creek confluence display similar type and magnitude of changes and (2) some of the increases at the confluence area pre-date the drawdowns. The cumulative effect of sediment releases from Fall Creek Lake streambed drawdowns from WY 2012 to 2016 on downstream channel planform and landforms are modest compared to the river-scale transformations and planform changes that occurred in the decades following dam construction. Chapter E. Discussion of Geomorphic Responses of Fall Creek and Middle Fork Willamette River to Streambed Drawdowns at Fall Creek Lake Multiple aspects of Fall Creek Dam infrastructure and operations exert first-order controls on the magnitudes of reservoir erosion that occur during the streambed drawdowns and ultimately determine the sediment delivery to downstream reaches. Key aspects of the dam and its operations that are most relevant to assessing geomorphic responses to streambed drawdowns include the (1) dam infrastructure, including configuration and size of regulating outlets and their proximity to the streambed which dictates the capacity and competence of the river to deliver sediment to downstream reaches and mode of sediment transport as suspended-sediment load or bedload; (2) frequency of historical drawdowns and long-term, year-round dam operations and lake level management, which partly dictate reservoir morphology and locations and magnitudes of readily erodible materials; (3) dam operations and hydroclimatic conditions during the streambed drawdown (including length of the drawdown and streamflows entering the reservoir), which directly control the timing, duration and magnitude of reservoir erosion and sediment evacuation; and (4) dam operations following the streambed drawdown operation that regulate streamflows (and thereby sediment transport conditions) downstream of Fall Creek Dam which primarily reflect interactions between hydroclimatic conditions and flood control operations. Patterns of sediment erosion and evacuation observed in this study at Fall Creek Lake from WY 2012–18 suggest that reservoir erosion during annual streambed drawdowns may remain similar or decrease in future years assuming (1) annual streambed drawdown operations are implemented in similar manner as the WY 2012–18 drawdowns (in terms of duration, late autumn or early winter implementation, rate of pool-level lowering to reach streambed, and other factors), (2) streambed drawdowns coincide with similar conditions as were observed WY 2012–18 (similar sediment yield into reservoir, low reservoir inflows, limited precipitation, moderate air temperature), and (3) no major geomorphic changes in the main reservoir channels of Fall and Winberry Creeks occur (for example, channel avulsion). Under such conditions, it is hypothesized that the stream channel within the reservoir would achieve a quasi-equilibrium state with respect to annual influx and export of sediment and aided by the substantial amount of in-channel bedrock, will remain laterally stable without erosion across reservoir deposits. Patterns of sediment transport measured at the Fall Creek streamgage downstream from Fall Creek Dam provide insight into the potential effects of future streambed drawdowns at Fall Creek Lake. Analyses of suspended sediment measured in WY 2013–18 show a major reduction in suspended-sediment loads between WY 2013 and later years, indicating streamflows transporting sediment through the reservoir to downstream reaches during streambed drawdowns have become supply limited. The 6-year suspended-sediment monitoring and sampling program is insufficient to make predictions about future sediment transport conditions because of uneven monitoring periods and varying controls on reservoir sediment erosion. It is likely that future suspended-sediment loads will be variable but similar to those observed in WY 2015–18 if operational, climatic, and geomorphological factors remain similar to those monitored WY 2015–18. Suspended-sediment loads downstream from Fall Creek Lake will likely remain highest when regulating outlets are fully open and Fall Creek is free flowing with the reservoir fully drained with little to no residual pool. Over time, it is possible that the suspended-sediment loads would reflect mobilization of reservoir sediment deposited in the previous year rather than erosion of sediment deposited years or decades earlier. Bedload is likely to remain a small fraction of the total sediment load evacuated from the reservoir and is relatively modest compared with pre-dam bedload transport rates because most coarse sediment remains trapped by the dam. If sediment releases from Fall Creek Lake and ensuing streamflow conditions follow a similar pattern in the future as was assessed in this study spanning WY 2012–18, near-term geomorphic adjustments downstream of the dam are expected to be modest. Barring major operational, climatic, and geomorphological changes, local site-scale deposition on bars, overbank areas, or off-channel features that persists several months after the streambed drawdown will likely continue to be highly variable, ranging from negligible to several centimeters of deposition. At the landform-scale, low velocity areas nearest to Fall Creek Dam will likely continue to undergo rapid deposition immediately during and after a streambed drawdown event, similar to patterns observed for WY 2012–18. Some of the sediment entering these off-channel features and margin areas may be temporarily stored, then later remobilized and dispersed farther downstream. But if newly deposited sediment persists through the following spring, there is a greater likelihood that local vegetation will establish, reinforce deposited material, and trap sediment during later drawdowns. The reach-scale geomorphic changes may become more apparent if (1) streambed drawdowns continued for several decades, and geomorphic changes were measured at decadal scales or (2) the amount of sediment introduced to downstream reaches substantially increased and (or) sediment transport capacity decreased. The continued streamflow regulation of Fall Creek Dam after sediment releases provides an opportunity to strategically manage streamflows during and after the streambed drawdowns to minimize downstream sediment impacts and ensure other operational thresholds are satisfied. This study provides a comprehensive foundation of datasets and geomorphic analyses to inform dam operations at Fall Creek Lake, monitor sediment transport downstream, and consider operational schemes for future drawdowns. The datasets from this study also provide baselines of sediment transport and geomorphic conditions to assess future changes in reservoir and downstream environments. Future monitoring could be tailored to address specific questions regarding the long-term geomorphic effects of streambed drawdowns on fluvial habitats, flood hazards, cultural resources, or downstream water quality. Future monitoring activities could focus on the relevant geomorphic processes and spatial domains within the three categories used for this study: (1) reservoir erosion and net sediment evacuation, (2) sediment delivery to downstream reaches, including magnitude and temporal pattern of sediment transport, and (3) geomorphic responses of downstream reaches to sediment delivery. Specifically, high priority future monitoring activities could include: Repeat topographic or photographic surveys in the reservoir to characterize changes occurring within individual drawdowns, to quantify sediment export, to determine temporal changes in reservoir storage, and to identify locations of erosion and deposition. Continuous, year-round turbidity monitoring supplemented with suspended-sediment measurements at a streamflow-gaging station immediately downstream from the dam to quantify sediment export. Repeat geomorphic monitoring, mapping, or modeling in downstream reaches to track changes in channel and over bank features using a combination of site- and reach-scale monitoring approaches. This could support assessments of sediment deposition and ensuing vegetation encroachment on flood hazards and habitats and examine how sediment transport and depositional processes may be affected by different sediment supply, streamflow, or dam management scenarios.

Oregon↗

USGS2026

Arsenic and isotope concentrations in the lower Platte River valley of eastern Nebraska, early 1970s to 2023

The City of Lincoln, Nebraska, has been monitoring concentrations of arsenic in their source water and evaluating their options for treatment and removal since at least 2002. In 2022, the City of Lincoln, Nebr., with funding assistance from the Nebraska Water Sustainability Fund, began cooperating with the U.S. Geological Survey to examine arsenic concentrations in surface water and groundwater in the lower Platte River valley and the area around City of Lincoln Water System (LWS) well field. Arsenic data collected from the Platte River since 1974 were examined using the “weighted regression on time, discharge, and season” model, which compared the streamflow (also referred to as “discharge”), time of year, and season to estimate concentrations of arsenic. Annual mean arsenic concentrations modeled for more than 49 years at the Platte River at Louisville, Nebr., U.S. Geological Survey streamgage (station 06805500), indicated a significant increasing trend. Arsenic concentrations in the Platte River were seasonal, with the highest concentrations being observed during mid- to late summer. When seasonal patterns and streamflow were combined with arsenic concentrations in the Platte River during low streamflow conditions, groundwater contributions, which can have higher arsenic concentrations, make up a larger portion of the streamflow. Arsenic samples were collected from upstream rivers in 2022 and 2023 and were paired to analyze the arsenic contributions at the U.S. Geological Survey streamgage on the Platte River near Ashland, Nebr. (station 06801000), near the City of Lincoln well field. The arsenic concentrations from the streamgage on the Platte River near Ashland, Nebr., location, were higher than the U.S. Geological Survey streamgage on the Elkhorn River at Waterloo, Nebr. (station 06800500), and significantly lower than at the U.S. Geological Survey streamgage on the Platte River near Leshara, Nebr.(station 06796500), indicating that the Platte River usually contributes a higher concentration of arsenic than does the Elkhorn River as they join near Ashland, Nebr. During 1991–2023, six groundwater monitoring wells were analyzed to identify trends in arsenic concentrations. Two of the six wells had a positive trend during the 33-year period. One monitoring well did not reveal a long-term trend during this period but showed a trend during 2019–23, correlating to a period when the island in the middle of the Platte River was connected to the east bank of the river when manganese reducing conditions were present and groundwater levels were declining in the well. Across all wells the oxidation and reduction (redox) condition during the time of sampling was assessed. Mixed anoxic and (or) oxic redox condition was the most common redox process and the highest sampled arsenic concentrations in monitoring wells were observed in anoxic conditions driven by manganese reduction. Groundwater arsenic concentrations had seasonal variation around the City of Lincoln well field, with higher arsenic concentrations tending to be further south in comparison to samples collected further north. Isotope samples were collected and analyzed in surface water and groundwater around the LWS well field. The samples indicate that the proportion of surface water present in the LWS production wells can be higher in the spring and lower in the summer. With higher arsenic concentrations observed in the stream water during the summer period, the LWS source water can be affected by these elevated arsenic concentrations even though the proportion of surface water is lower.

Nebraska↗

USGS2003

Trends in concentrations of polychlorinated biphenyls in fish tissue from selected sites in the Delaware River basin in New Jersey, New York, and Pennsylvania, 1969-98

Polychlorinated biphenyl (PCB) concentrations in fish tissue collected during the 1990's from selected sites in the Delaware River Basin were compared with concentrations in fish tissue collected during 1969-88. Data collected by State and Federal agencies on concentrations in whole-body common carp ( Cyprinus carpio ) and white sucker ( Catostomus commersoni ), and edible portions of American eel ( Anguilla rostrata ), smallmouth bass ( Micropterus dolomieu ), and channel catfish ( Ictalurus punctatus ) during 1969-98 were compiled to define temporal trends in concentrations of PCBs in fish tissue from selected segments of the Delaware River, Lehigh River, Schuylkill River, and Brandywine Creek. The Delaware River in the vicinity of Trenton, New Jersey and Yardley, Pennsylvania (above the tidal influence) had the largest long-term data set among the sites considered for this study and was the only site with sufficient data for statistical analysis. A general pattern of decline in PCB concentrations during 1969-98 was apparent for this river segment. PCB concentrations in whole-body white sucker from this lower Delaware River segment declined during 1969-98 from a highest concentration of 7 micrograms per gram ( μ g/g, wet weight) in a sample collected during 1972 to 0.26 μ g/g (wet weight) in a sample collected during 1998. PCB concentration was negatively correlated with year (Spearman rank correlation -0.46, p < 0.08, n = 15); especially after removal of a sample from 1977 with an unusually low concentration (Spearman rank correlation -0.53, p = 0.05, n = 14). PCB concentrations in edible flesh of American eel declined during 1975-95, from a highest concentration of 3.8 μ g/g (wet weight) in a sample collected during 1976 to less than the reporting limit of 0.26 μ g/g (wet weight) in samples collected during 1993 and 1995. PCB concentrations in most samples (for species considered in this study) collected from the lower Delaware River exceeded the National Academy of Sciences and National Academy of Engineering (NAS/NAE) wildlife guideline level of 0.5 μ g/g during the 1970's and 1980's, and decreased to below this level during the 1990's. No samples of edible portions of game fish exceeded the U.S. Food and Drug Administration (FDA) tolerance level by the mid 1980's. However, the PCB concentration in a smallmouth bass fillet sample that was collected during 1998 (0.37 μ g/g) exceeded the Pennsylvania fish-consumption advisory level of 0.06 μ g/g, and the concentrations in whole-body common carp and white sucker collected during 1998 (1.10 μ g/g and 0.26 μ g/g, respectively) exceeded the New York State Department of Environmental Conservation wildlife criterion concentration of 0.11 μ g/g. (The concentration in carp also exceeded the 1973 NAS/NAE wildlife guideline concentration of 0.5 μ g/g.) Graphical analysis of PCB concentrations in whole white sucker and (or) edible portions of American eel from the upper Delaware River, lower Delaware River, middle Schuylkill River, and Brandywine Creek indicate a decline from the 1970's and (or) 1980's to the middle to late 1990's. Temporal trends in PCB concentrations in white sucker samples from the lower Lehigh and Schuylkill Rivers during 1979-98 are less clear; the PCB concentration (wet-weight basis) from a sample collected in 1998 from the lower Lehigh River was similar to that from a sample collected in 1979, and concentrations actually increased during 1982-98. Similarly, PCB concentrations in samples of white sucker and American eel from the lower Schuylkill River were highly variable over time.

New Jersey, New York, Pennsylvania↗

USGS2002

Water Quality in the Mahoning River and Selected Tributaries in Youngstown, Ohio

The lower reaches of the Mahoning River in Youngstown, Ohio, have been characterized by the Ohio Environmental Protection Agency (OEPA) as historically having poor water quality. Most wastewater-treatment plants (WWTPs) in the watershed did not provide secondary sewage treatment until the late 1980s. By the late 1990s, the Mahoning River still received sewer-overflow discharges from 101 locations within the city of Youngstown, Ohio. The Mahoning River in Youngstown and Mill Creek, a principal tributary to the Mahoning River in Youngstown, have not met biotic index criteria since the earliest published assessment by OEPA in 1980. Youngstown and the OEPA are working together toward the goal of meeting water-quality standards in the Mahoning River. The U.S. Geological Survey collected information to help both parties assess water quality in the area of Youngstown and to estimate bacteria and inorganic nitrogen contributions from sewer-overflow discharges to the Mahoning River. Two monitoring networks were established in the lower Mahoning River: the first to evaluate hydrology and microbiological and chemical water quality and the second to assess indices of fish and aquatic-macroinvertebrate-community health. Water samples and water-quality data were collected from May through October 1999 and 2000 to evaluate where, when, and for how long water quality was affected by sewer-overflow discharges. Water samples were collected during dry- and wet-weather flow, and biotic indices were assessed during the first year (1999). The second year of sample collection (2000) was directed toward evaluating changes in water quality during wet-weather flow, and specifically toward assessing the effect of sewer-overflow discharges on water quality in the monitoring network. Water-quality standards for Escherichia coli ( E. coli ) concentration and draft criteria for nitrate plus nitrite and total phosphorus were the regulations most commonly exceeded in the Mahoning River and Mill Creek sampling networks. E. coli concentrations increased during wet-weather flow and remained higher than dry-weather concentrations for 48 hours after peak flow. E. coli concentration criteria were more commonly exceeded during wet-weather flow than during dry-weather flow. Exceedances of nutrient-concentration criteria were not substantially more common during wet-weather flow. The fish and aquatic macroinvertebrate network included Mill Creek and its tributaries but did not include the main stem of the Mahoning River. Persistent exceedances of chemical water-quality standards in Mill Creek and the presence of nutrient concentrations in excess of draft criteria may have contributed to biotic index scores that on only one occasion met State criteria throughout the fish and aquatic macroinvertebrate sampling network. Monitored tributary streams did not contribute concentrations of E. coli , nitrate plus nitrite, or total phosphorus to the Mahoning River and Mill Creek that were higher than main-stem concentrations, but monitored WWTP and sewer-overflow discharges did contribute. Twenty-four hour load estimates of sewer-overflow discharge contributions during wet-weather flow indicated that sewer-overflow discharges contributed large loads of bacteria and inorganic nitrogen to the Mahoning River relative to the instream load. The sewer-overflow loads appeared to move as a slug of highly enriched water that passed through Youngstown on the rising limb of the storm hydrograph. The median estimated sewer-overflow load contribution of bacteria was greater than the estimated instream load by a factor of five or more; however, the median estimated sewer-overflow load of inorganic nitrogen was less than half of the estimated instream load. Sewer-overflow discharges contributed loads of E. coli and nutrients to the Mahoning River and Mill Creek at a point where the streams already did not meet State water-quality regulations. Improvement of water quality of the Mahoning River, Mill Creek, and tributaries at Youngstown would be facilitated by reducing loads from sewer-overflow discharges within Youngstown, by identifying and reducing other sources of E. coli and nutrients within Young-stown, and by reducing discharges of E. coli , nitrate plus nitrite, and total phosphorus to the Mahoning River and Mill Creek upstream from Youngstown.

Water-Resources Investigations Report↗

USGS2002

Streamflow and nutrient data for the Yazoo River below Steele Bayou near Long Lake, Mississippi, 1996-2000

Increased nutrient loading to the Gulf of Mexico from off-continent flux has been identified as contributing to the increase in the areal extent of the low dissolved-oxygen zone that develops annually off the Louisiana and Texas coast. The proximity of the Yazoo River Basin in northwestern Mississippi to the Gulf of Mexico, and the intensive agricultural activities in the basin have led to speculation that the Yazoo River Basin contributes a disproportionate amount of nitrogen and phosphorus to the Mississippi River and ultimately to the Gulf of Mexico. An empirical measurement of the flux of nitrogen and phosphorus from the Yazoo Basin has not been possible due to the hydrology of the lower Yazoo River Basin. Streamflow for the Yazoo River below Steele Bayou is affected by backwater from the Mississippi River. Flow at the gage is non-uniform and varying, with bi-directional and reverse flows possible. Streamflow was computed by using remote sensing and acoustic and conventional discharge and velocity measurement techniques. Streamflow from the Yazoo River for the 1996-2000 period accounted for 2.8 percent of the flow of the Mississippi River for the same period. Water samples from the Yazoo River were collected from February 1996 through December 2000 and were analyzed for total nitrogen, nitrate, total phosphorus, and orthophosphorus as part of the U.S. Geological Survey National Water-Quality Assessment Program. These data were used to compute annual loads of nitrogen and phosphorus discharged from the Yazoo River for the period 1996-2000. Annual loads of nitrogen and phosphorus were calculated by two methods. The first method used multivariate regression and the second method multiplied the mean annual concentration by the total annual flow. Load estimates based on the product of the mean annual concentration and the total annual flow were within the 95 percent confidence interval for the load calculated by multivariate regression in 10 of 20 cases. The Yazoo River loads, compared to average annual loads in the Mississippi River, indicated that the Yazoo River was contributing 1.4 percent of the total nitrogen load, 0.7 percent of the nitrate load, 3.4 percent of the total phosphorus load, and 1.6 percent of the orthophosphorus load during 1996 - 2000. The total nitrogen, nitrate, and orthophosphorus loads in the Yazoo River Basin were less than expected, whereas the total phosphorus load was slightly higher than expected based on discharge.

Water-Resources Investigations Report↗

USGS1986

Hydrologic reconnaissance of the Unalakleet River basin, Alaska, 1982-83

The Unalakleet River, Alaska, from its headwaters to the confluence of the Chiroskey River has been designated as a wild river and is included in the National Wild and Scenic Rivers System. Yearly low flow, which occurs during the winter, is sustained by groundwater discharge; there are few lakes in the basin and the cold climate prevents winter runoff. The amount of winter streamflow was greatest in the lower parts of streams with the exception of the South River and was apparently proportional to the amount of unfrozen alluvium upstream from the measuring sites. Unit discharge in late winter ranged from nearly zero at the mouth of the South River to 0.24 cu ft/sec/sq mi in the Unalakleet River main stem below Tenmile River. Summer runoff at the time of the reconnaissance may have been slightly higher than normal owing to recent rains. Unit runoff ranged from a low of 1.0 cu ft/sec/sq mi at the South River, to a high value of 2.4 cu ft/sec/sq mi at the North Fork Unalakleet River. Flood marks were present in the basin well above streambank levels but suitable sections to measure the maximum evident flood by slope-area methods were not found. Flood peaks were calculated for the Unalakleet River and its tributaries using basin characteristics. Calculated unit runoff for the 50-year flood ranged from about 17 to 45 cu ft/sec/sq mi. Water quality was good throughout the basin, and an abundant and diversified community of benthic invertebrates was found in samples collected during the summer reconnaissance. Permafrost underlies most of the basin, but groundwater can be found in unfrozen alluvium in the stream valleys, most abundantly in the lower part of the main tributaries and along the main stem of the Unalakleet River. Groundwater sustains river flow through the winter; an estimate of its quantity can be found through low-flow measurements. Groundwater quality in the basin appears to be satisfactory for most uses. Currently, little groundwater is used within the basin. The water supply for Unalakleet is obtained from a well and gallery in a small valley north of the airport, outside the Unalakleet River basin. (Author 's abstract)

Water-Resources Investigations Report↗

USGS1989

Streamflow and stream quality in the coal-mining region, Patoka River basin, southwestern Indiana, 1983-85

Streamflow and stream-quality data were collected for surface water in the coal-mining region of the Patoka River basin. Data were collected primarily in Pike County. Data were collected 4 times at 29 surface-water sites during different seasons and conditions of Streamflow. Data were collected August 1983, July 1984, December 1984, and February through March 1985. Six sites were on the Patoka River. Although the percentage of drainage from coal-mined lands increases from the upstream to the downstream sites, the major land use for all sites on the Patoka River is agriculture. Ten sites were on 8 tributaries to the Patoka River (excluding the South Fork Patoka River), 3 sites were on the South Fork Patoka River (the largest tributary to the Patoka River), and 10 sites were on 10 tributaries to the South Fork Patoka River. The major land use for these sites is coal mining. Data obtained at the sites included instantaneous Streamflow, pH, specific conductance, dissolved-oxygen concentration, water temperature and concentrations of alkalinity and hot acidity. Water samples were collected and analyzed to determine the concentrations of dissolved sulfate; dissolved, suspended, and total recoverable iron and manganese; dissolved solids; suspended sediment; and suspended sediment finer than 0.0625-millimeter diameter. Streamflow in the Patoka River has been regulated since 1978 by Patoka Lake. Flow-duration analyses indicate that flow regulation by Patoka Lake generally has increased low streamflows and decreased high streamflows in the Patoka River. When compared to sites on the tributaries, sites on the Patoka River generally had smaller values for specific conductance and concentrations of chemical constituents. Sites on the tributaries to the Patoka River (including the South Fork Patoka and its tributaries) had larger values due to the physical and chemical weathering of coal-mined material in their basins. Generally, for sites on the Patoka River, values of specific conductance and concentrations of dissolved sulfate and dissolved, suspended, and total recoverable manganese increased from the upstream to the downstream sites. For the tributary sites, pH was near neutral at 11 sites (median pH value of 7.3 for all samplings), pH was low at 8 sites (median pH value of 3.7 for all samplings), and pH was variable at 3 sites depending on Streamflow. At sites where pH was near neutral, when compared with sites where pH was low, specific conductance and concentrations of alkalinity, dissolved sulfate, suspended iron, suspended manganese, dissolved solids, and suspended sediment generally were larger, and concentrations of acidity, dissolved iron, total recoverable iron, dissolved manganese, and total manganese generally were smaller. At those sites where pH varied with streamflow, concentrations of chemical constituents also varied. For sites on the Patoka River, loads of dissolved sulfate, total recoverable manganese, and dissolved solids generally increased from the upstream to the downstream sites; loads of total recoverable iron were variable. Generally, there was an inverse relation of streamflow to concentrations of chemical constituents the greater the streamflow, the smaller the concentrations. For sites on the tributaries, there was an inverse relation of streamflow to specific conductance and to concentrations of alkalinity, acidity, dissolved sulfate, and dissolved solids and a direct relation of streamflow to concentrations of dissolved, suspended, and total iron. Data collected from 1965 through 1968 and during May and October 1979 were compared with data collected during the time of the study (1983-85). Few historical data were available, and those that were available were only for selected sites. Data for pH, alkalinity, acidity, and dissolved sulfate indicate minimal or no change in these constituents.

Indiana↗

USGS1997

Surface-water-quality assessment of the upper Illinois River Basin in Illinois, Indiana, and Wisconsin– Results of investigations through April 1992

A water-quality assessment of the upper Illinois River Basin (10,949 square miles) was conducted during water years 1987-91. This assessment involved interpretation of available data; 4 years of intensive data collection, including monthly sample collection at eight fixed-monitoring stations in the basin; and synoptic studies of selected water-quality constituents at many sites. The number of exceedances of water-quality criteria for chromium, copper, lead, mercury, silver, and zinc in water was essentially the same at similar stations between 1978-86 and 1987-90. For water and sediment, a large signature for many trace inorganic constituents was observed from the Chicago metropolitan area, mainly from the Des Plaines River Basin and continuing down the Illinois River. Loads of trace inorganic constituents in water were 2-13 times greater from the Chicago metropolitan area than from rural areas in the upper Illinois River Basin. Concentrations of cadmium, mercury, nickel, selenium, and zinc appeared to be relatively enriched in biota in the upper Illinois River Basin compared to other river basins. Biota from some urban sites were enriched with respect to several elements. For example, relatively large concentrations of cadmium, chromium, copper, lead, and nickel were observed in biota from sites in the Chicago River in the metropolitan area and the Calumet River. Results of pesticide sampling in 1988 and 1989 identified the pesticides bromacil, diazinon, malathion, prometon, and simazine as urban related and alachlor, atrazine, cyanazine, metolachlor, and metribuzin as agricultural related. Phenol concentrations never exceeded general-use and secondary-contact water-quality standards of 100 and 300 micrograms per liter, respectively. Pentachlorophenol concentrations observed at the Illinois River at Marseilles, Ill., between 1981 and 1992 decreased beginning in 1987. A breakdown product of the organochlorine pesticide dichloro-diphenyl-trichloroethane (DDT), p,p'-DDE was the most commonly detected organic compound in biota in both 1989 and 1990. In the nine fish-fillet samples collected in 1989, exceedances of U.S. Environmental Protection Agency (USEPA) fish tissue concentrations were noted for p,p'-DDE in all nine fillets and for dieldrin in five of the nine fillets. Nutrient concentrations in water in the study area generally were larger than concentrations typically found in natural waters. The Des Plaines River Basin contributed approximately 41 percent of the total nitrogen load to the upper Illinois River Basin, whereas the Kankakee River and Iroquois River Basins contributed about 34 and 14 percent of the total load, respectively. Dissolved-oxygen concentrations measured during a 1988 synoptic sampling exceeded State water-quality standards at 76 percent of the sampled sites. Bacteria densities greater than water-quality standards were observed at all of the fixed-monitoring stations, but densities greater than water-quality criteria and standards were observed more often at stations in the Des Plaines River Basin. Results from the analysis of changes in water quality following changes in wastewater-treatment practices indicated that current monitoring programs, although sufficient for their intended purposes, are not suitable for this type of retrospective assessment in large-scale water-quality assessments. Changes were not indicated in fish-community structure and population following changes in wastewater-treatment practices. A strong relation between the quality of the fish community and overall water-quality conditions was observed, although USEPA acute criteria for the protection of freshwater aquatic life were rarely exceeded. Analyses of fish-community data clearly showed that water quality in the urbanized parts of the study area were degraded relative to those in agricultural areas. Total chromium in streambed sediments and total recoverable sodium in water were highly correlated

Illinois, Indiana, Wisconsin↗

USGS1998

Simulation of ground-water flow and stream-aquifer relations in the vicinity of the Savannah River Site, Georgia and South Carolina, predevelopment through 1992

Ground-water flow and stream-aquifer relations were simulated for seven aquifers in Coastal Plain sediments in the vicinity of the U.S. Department of Energy, Savannah River Site (SRS), in Georgia and South Carolina to evaluate the potential for ground water containing hazardous materials to migrate from the SRS into Georgia through aquifers underlying the Savannah River (trans-river flow). The work was completed as part of a cooperative study between the U.S. Geological Survey, the U.S. Department of Energy, and Georgia Department of Natural Resources. The U.S. Geological Survey three-dimensional finite-difference ground-water flow model, MODFLOW, was used to simulate ground-water flow in three aquifer systems containing seven discrete aquifers: (1) the Floridan aquifer system, consisting of the Upper Three Runs and Gordon aquifers in sediments of Eocene age; (2) the Dublin aquifer system, consisting of the Millers Pond, and upper and lower Dublin aquifers in sediments of Paleocene and Late Cretaceous age; and (3) the Midville aquifer system, consisting of the upper and lower Midville aquifers of sediments in Late Cretaceous age. Ground-water flow was simulated using a series of steady-state simulations of predevelopment (pre-1953) conditions and six pumping periods--1953-60, 1961-70, 1971-75, 1976-80, 1981-86, and 1987-92--results are presented for predevelopment (prior to 1953) and modern-day (1987-92) conditions. Total simulated predevelopment inflow is 1,023 million gallons per day (Mgal/d), of which 76 percent is contributed by leakage from the Upper Three Runs aquifer. Over most of the study area, pumpage induced changes in ground-water levels, ground-water discharge to streams, and water-budget components were small during 1953-92, and changes in aquifer storage were insignificant. Simulated drawdown between predevelopment and modern-day conditions is small (less than 7 feet) and of limited areal extent--the largest simulated declines occur in the upper and lower Dublin aquifers in the vicinity of the Sandoz plant site in South Carolina. These declines extend beneath the Savannah River and change the configuration of the simulated potentiometric surface and flow paths near the river. Predevelopment and modern-day flowpaths were simulated near the Savannah River by using the U.S. Geological Survey particle-tracking code MODPATH. Eastward and westward zones of trans-river flow were identified in three principal areas as follows: --zone 1-from the Fall Line southward to the confluence of Hollow Creek and the Savannah River; --zone 2-from the zone 1 boundary southward to the southern border of the SRS (not including the Lower Three Runs Creek section); and --zone 3-from the zone 2 boundary, southward into the northern part of Screven County, Ga. All zones for all model layers were located within or immediately adjacent to the Savannah River alluvial valley and most were located in the immediate vicinity of the Savannah River. Recharge areas for each of the zones of trans-river flow generally are in the vicinity of major interstream drainage divides. Mean time-of-travel simulated for predevelopment conditions ranges from 300 to 24,000 years for westward trans-river flow zones; and from 550 to 41,000 years for eastward zones. Corresponding travel times under modern-day conditions range from 300 to 34,000 years for westward zones and from 580 to 31,000 years for eastward zones. Differences in travel times between predevelopment and modern-day simulations result from changes in hydraulic gradients due to ground-water pumpage that alter flow paths in the vicinity of the river. Recharge to Georgia trans-river flow zones originating on the SRS was simulated for the Gordon and upper Dublin aquifers during predevelopment, and in the Gordon aquifer during 1987-92. During 1987-92, SRS recharge was simulated in 6 model cells covering a 2-square mile area, located away from areas of ground-water contamination. Si

Georgia, South Carolina↗

USGS2000

Occurrence of pesticides in five rivers of the Mississippi Embayment Study Unit, 1996-98

The occurrence and temporal distribution of more than 80 pesticides and pesticide metabolites were determined in five rivers of the Mississippi Embayment National Water-Quality Assessment study unit from February 1996 through January 1998. More than 230 samples were collected and analyzed during the 2-year study. The five rivers sampled included three rivers with small, primarily agricultural watersheds; one river with a small urban watershed in Memphis, Tennessee; and one large river with mixed land use (row-crop agriculture, pasture, forest, and urban). Pesticides, usually herbicides, were frequently detected in water samples from every river. Insecticides were frequently detected (chlorpyrifos and diazinon in all samples) only in the river that drains the urban watershed. The occurrence of pesticides in surface water varied among the agricultural watersheds as well as between the agricultural and urban watersheds. The pesticides detected in the rivers that drain the agricultural watersheds were related to the major crop types cultivated in the watershed?corn is mostly grown in the northern part of the study unit, whereas cotton and rice are mostly grown in the southern part. The occurrence of pesticides in the Yazoo River, which drains the mixed land-use watershed, was similar to pesticide occurrence in the rivers that drain smaller agricultural watersheds, although concentrations were lower in the Yazoo River. Likewise, simazine, which was detected in all urban stream samples, was also detected in all Yazoo River samples, but in lower concentrations. The aquatic-life criteria for diazinon and chlorpyrifos was exceeded in 24 of 25 and 12 of 25 urban river samples, respectively, but only once or twice in agricultural and mixed-use watershed samples. Atrazine exceeded the aquatic-life criterion in about 20 percent of the samples from each river, particularly in the spring following pesticide application.

Water-Resources Investigations Report↗

USGS1964

Preliminary results of hydrogeologic investigations in the valley of the Humboldt River near Winnemucca, Nevada

Most of the ground water of economic importance and nearly all the ground water closely associated with the flow o# the Humboldt River in the. 40-mile reach near Winnemucca, Nev., are in unconsolidated sedimentary deposits. These deposits range in age from Pliocene to Recent and range in character from coarse poorly sorted fanglomerate to lacustrine strata of clay, silt, sand, and gravel. The most permeable deposit consists of sand and gravel of Lake Lahontan age--the so-called medial gravel unit--which is underlain and overlain by fairly impermeable silt and clay also of Lake Lahontan age. The ultimate source of nearly all the water in the study area is precpitation within the drainage basin of the Humboldt River. Much of this water reaches the study, area as flow or underflow of the Humboldt River and as underflow from other valleys tributary to the study area. Little if any flow from the tributary streams in the study area usually reaches the Humboldt River. Most of the tributary streamflow within the study area evaporates or is transpired by vegetation, but a part percolates downward through unconsolidated deposits of the alluvial fans flanking the mountains and move downgradient as ground-water underflow toward the Humboldt River. Areas that contribute significant amounts of ground-water underflow to. the valley of the Humboldt River within the study area are (1) the valley of the Humboldt River upstream from the study area, (2) the Pole Creek-Rock Creek area, (3) Paradise Valley, and (4) Grass Valley and the northwestern slope of the Sonoma Range. The total average underflow from these areas in the period 1949-61 was about 14,000-19,000 acre-feet per year. Much of this underflow discharged into the Humboldt River within the study area and constituted a large part of the base flow of the river. Streamflow in the Humboldt River increases substantially in the early spring, principally because of runoff to the river in the reaches upstream from the study area. The resulting increase of the stage of the river causes the river to lose large amounts of water by infiltration to the ground-water reservoir in the study area. In addition, there is much recharge to the ground-water reservoir in the spring and early summer as a result of seepage losses from irrigation ditches and the downward percolation of some of the excess water applied for irrigation. The average net increase of ground water in storage in the deposits beneath and adjacent to the flood plain of the Humboldt River during the spring and early summer is about 10,000 acre-feet.

Nevada↗

USGS1964

Chemical quality of surface waters in the Brazos River basin in Texas

The Brazos River basin, which makes up 15 percent of the land area of Texas, extends from the High Plains, where altitudes reach 4,200 feet and the average precipitation ranges from 15 to 20 inches a year, to the Gulf of Mexico where the annual rainfall is 45-^50 inches. Large reservoirs have been built in the Brazos River basin, but the use of the stored water has been limited because the salinity often makes the water undesirable for municipal and industrial use. However, the water is generally satisfactory for irrigation. Records for the Brazos River show that the salinity of the water was a problem even as early as 1906 and that the water more often than not failed to meet today's chemical-quality standards for a municipal supply. The salt load of the Brazos River comes from the entire basin and is the result of solution, accretion of undetermined amounts of oil-field brine, and accretion of brine from springs and seeps such as those in Salt Croton Creek which contribute about 400 tons of chloride a day. Much of the salinity of the Brazos River is due to inflow of brines above Possum Kingdom Dam. The area above Possum Kingdom Dam is about 52 percent of the total area in the Brazos River basin but contributes only about 17 percent of the total runoff; however, about 50 percent of the annual salt load comes from this part of the basin. Quality-of-water records show a wide difference in the salinity of the steams in different parts of the basin, Dissolved-solids concentrations ranged from about 100 ppm (parts per million) for flood water to 300,000 ppm for saturated brines from springs. The quality of the surface water in the Brazos River basin is discussed by areas and by stream reaches. This study indicates that the water of the Salt Fork Brazos River is too saline for most uses. The water of the Double Mountain Fork Brazos River is less saline and might be used for irrigation; however, it probably could not be used as a municipal supply or as a supply for most industries. The water of the dear Fork Brazos River is generally good but is adversely affected by brine pollution. Chemical-quality records for the Lampasas, Leon, and Navasota Rivers indicate that the water of these streams is of excellent quality; however, more data are needed to determine variations. The quality of the water in other tributaries could only be inferred from the results of miscellaneous sampling and from the probable effect of the underlying rocks. The weighted-average concentration of constituents in the Brazos River at Richmond indicated that inflow below Whitney Reservoir has a dilution effect on the river. For 12 of the 14 years of record, the weighted-average dissolved-solids concentration of the Brazos River at Richmond was lessi than, the 500 ppm maximum limit recommended by the U.S. Public Health Service (1961). This study indicates that water stored in Possum Kingdom and Whitney Reservoirs tends to become stratified, with the more saline water being at the greater depths. Samples collected in 1956 at Whitney Reservoir showed that the chloride concentration at the bottom was almost twice that at the surface. After a flood in June 1957, the dissolved-solids concentrations of bottom releases at Possum Kingdom were almost double those of surface releases through the spillway even though the flood volume had been more than twice the capacity of the reservoir. The quality of water in the lower main stem can be improved by control and disposal of brines in the upper basin. Also, the maximum concentrations in the water of the lower main stem can be lowered by dilution with water stored in reservoirs on tributaries that yield water of good quality.

Water Supply Paper↗

USGS2012

Hood River PIT-tag interrogation system efficiency study. Annual report of U.S. Geological Survey activities: November 2010-October 2011

Introduction During summer 2010, an agreement was made between the US Geological SurveyColumbia River Research Laboratory (USGS-CRRL) and the Confederated Tribes of the Warm Springs (CTWS) to operate an experimental Passive Integrated Transponder (PIT)-tag interrogation system (PTIS) near the mouth of the Hood River for a year and provide fishdetection efficiency estimates (Bonneville Power Administration (BPA) project number 1988- 053-03, contract number 50150). A previous agreement between Oregon Department of Fish and Wildlife (ODFW) and USGS-CRRL had funded materials acquisition, construction, and installation of the PTIS (BPA project number 1988-053-04, contract number 48684). The primary purpose of the project was to test the efficacy of a PTIS in the lower Hood River for providing data on returning adult salmonids to the Hood River as part of the Hood River Production Monitor and Evaluation project (HRPME). Because PIT tags are small, relatively inexpensive, carry no internal battery, and last through the lifespan of most fishes, they are commonly used in long term fish monitoring projects. They have been extensively used in the Columbia River basin to monitor salmonid behavior and survival through life stages and migration routes in the mainstem Columbia River (Skalski et al. 1998; Zabel and Achord 2004). Increasingly, PIT-tag detection equipment has been deployed in streams to investigate salmonid behavior (Zydlewski et al. 2001, 2006; Riley et al. 2003; Bond et al. 2007). Most of the detection systems deployed and evaluated to date have been in much smaller streams than the mainstem of the Hood River (Zydlewski et al. 2001, 2006; Bond et al. 2007; Horton et al. 2007; Connolly et al. 2008), but researchers are attempting to expand detection abilities to larger streams and rivers. Large streams and rivers can prove extremely challenging to monitor. Some systems have showed promise for contributing valuable detection data, others have proved less successful. A detection system in the Klamath River (Beeman et al. 2012), a site similar in size to the Hood River, suffered problems from cables being dislodged and high water that resulted in a detection efficiency estimate for juvenile coho salmon of less than 0.05. An additional USGS-CRRL task, under contract number 50150, was to build three antennas for use with Destron-Fearing 2001F-ISO PIT tag readers. These antennas would be 5 used at the East Fork Hood River Acclimation site. They would be placed in the outflow channel to inform managers about the number of PIT tagged steelhead smolts released to the Hood River after a period of acclimation when some mortality and predation might occur.

Oregon↗

USGS2007

Status of Shortnose Sturgeon in the Potomac River. Part 1: Field Studies

Field studies during more than 3 years (March 2004–July 2007) collected data on life history of Potomac River shortnose sturgeon Acipenser brevirostrum to understand their biological status in the river. We sampled intensively for adults using gill nets, but captured only one adult in 2005. Another adult was captured in 2006 by a commercial fisher. Both fish were females with excellent body and fin condition, both had mature eggs, and both were telemetrytagged to track their movements. The lack of capturing adults, even when intensive netting was guided by movements of tracked fish, indicated abundance of the species was less than in any river known with a sustaining population of the species. Telemetry tracking of the two females (one during September 2005–July 2007, one during March 2006–February 2007) found they remained in the river for all the year, not for just a few months like sturgeons on a coastal migration. Further, one fish used the same freshwater reach during three summers. The two sturgeons used different reaches during some seasons, with one fish using saline water more than the other. The adults homed to small reaches in the same month each year, like shortnose sturgeon in their natal river. The total reach used by tracked sturgeons was 124 km (rkm 63–187), of which the lowermost 78 km, which was used for summering and wintering, contained the freshwater: saltwater interface. The most upstream reach used (rkm 185–187) contained potential spawning habitat. This reach was visited by one female on a pre-spawning migration in April 2006, but spawning was likely unsuccessful. Water quality (dissolved oxygen and temperature) in the summering–wintering reach was adequate all the year, although during the summer it was minimally acceptable. We periodically recaptured the same tagged female and found she healed well after tagging, appeared healthy in body and fins, grew well, and rapidly matured a new clutch of eggs. All surveys indicated adults had sufficient habitat and water quality needed to complete their life history. While we studied only two adults, all data strongly suggests shortnose sturgeons are a permanent resident of the Potomac River diadromous fish community. Life-history movements of the Potomac River adults were similar to adults in northcentral rivers, like the Delaware River, not to adults in southern rivers. We did not identify a unique life history behavior that separated Potomac River adults from other populations. Life history data indicates Potomac River shortnose sturgeons are most likely remnants of the natal population or colonizers from a north-central river, like the Delaware River.

Report↗