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USGS1974

Water quality and streamflow characteristics, Raritan River Basin, New Jersey

The findings of a problem-oriented river-system investigation of the stream-quality and streamflow characteristics of the Raritan River basin (1,105 square miles or 2,862 square kilometers drainage area) are described. The investigation covers mainly the period 1955-72. Precipitation in the basin is classified as ample and averages 47 inches or 120 centimeters per year (3-5 inches or 8-12 centimeters per month). During the study period four general precipitation trends were noted: less than normalin 1955-61 and 1966-70; extreme drought in 1962-66; and above normal in 1971-72. Analyses of streamflow measurements at eight gaging stations indicate a general trend toward lower flows during the study period, which is attributed to generally lower than normal precipitation. Highest flows were observed in 1958, concurrent with maximum annual precipitation; whereas lowest flows were observed in 1965 during extreme drought conditions. Non-tidal streams in the basin are grouped into three general regions of similar chemical quality based upon predominant constituents and dissolved-solids concentration during low-flow conditions. The predominant cations in solution in all regions are calcium and magnesium (usually exceeding 60 percent of total cation content). In headwater streams of the North and South Branch Raritan Rivers, bicarbonate is the predominant anion; a combination of sulfate, chloride, and nitrate are the predominant anions in the other two regions. The dissolved-solids concentration of streams in areas little influenced by man's activities generally range from 40 to 200 mg/L. Those in areas influenced by man often range much higher sometimes exceeding 800 mg/L. Suspended-sediment yields in the basin range from 25 to 500 tons per square mile annually. The water quality of the Raritan River and most tributaries above Manville (784 square miles of 2,030 square kilometers drainage area) generally is good for most industrial, domestic, and recreational uses, although pollution has been reported locally in some areas. A comparison of chemical analyses of water collected at several sampling sites in the 1920's with more recent data, however, indicate that there has been a significant increase in sulfate, chloride, and nitrate ions transported per unit of streamflow. These increases reflect increased waste-water discharges and nutrients in agricultural runoff in the upper basin. Trends in the dissolved-solids and dissolved-oxygen concentation of water in the Raritan and MIllstone Rivers above their confluence at Manville are described. The dissolved solids of the Millstone River are shown to increase, particularly at low streamflows. For example, at a flow of 100 cubic feet per second (2.83 cubic meters per second) this river tansported 13 percent more dissolved solids in 1969-70 than it did in 1957-58. A similar trend, however, was not apparent on the Raritan River. This phenomenon is attributed to dilution provided since 1964 by upstream reservoir releases during low flows. With the exception of low-flow periods on the Raritan River, dissolved-oxygen concentrations showed little or no significant time trends at Manville on either the Raritan or Millstone River. An improvement in dissolved-oxygen content at flows lower than 100 cubic feet per second (2.83 cubic meters per second) is observed with time on the Raritan River. This improvement is attributed to generally better quality water and dilution of nonconservative pollutants by upstream reservoir releases during low flows. The Raritan River between Manville and Perth Amboy flows through a large urban and industrial complex. Much of this reach is tidal. Detrimental activities of man are reflected in higher concentrations of most constituents below Manville than those observed upstream. For example, between Manville and the head of tide near South Bound Brook, the maximum concentration of dissolved solids observed during the study period increased from 464 to 1,520 mg/L; orthophosphates from 0.93 to 2.3 mg/L; phenolic materials from 22 to 312 μg/L; and coliform bacteria from 13,300 to 100,000 colonies per 100 milliliters. A general deterioration in water quality with time in the river below Manville is demonstrated through comparisons of dissolved-oxygen and biochemical-oxygen demand data collected between the late 1920's and early 1970's. Several time-of-travel measurements within the basin are reported. These data provide reasonable estimates of the time required for soluble contaminants to pass through particular parts of the river system. For example, the peak concentration of a contaminant injected into the river system at Clinton at a flow of 100 cubic feet per second (2.83 cubic meters per second) would be expected to travel to the head of tide near South Bound Brook, about 34 miles (55 kilometers), in about 70 hours; but at a flow of 50 cubic feet per second (1.42 cubic meters per second) the traveltime would increase to about 125 hours.

New Jersey↗

USGS1994

Method to identify wells that yield water that will be replaced by Colorado River water in Arizona, California, Nevada, and Utah

Accounting for the use of Colorado River water is required by the U.S. Supreme Court decree, 1964, Arizona v. California . Water pumped from wells on the flood plain and from certain wells on alluvial slopes outside the flood plain is presumed to be river water and is accounted for as Colorado River water. A method was developed to identify wells outside the f1ood plain of the lower Colorado River that yield water that will be replaced by water from the river. The method provides a uniform criterion of identification for all users pumping water from wells. Wells that have a static water-level elevation equal to or below the accounting surface are presumed to yield water that will be replaced by water from the river. Wells that have a static water-level elevation above the accounting surface are presumed to yield water that will be replaced by water from precipitation and inflow from tributary valleys. The method is based on the concept of a river aquifer and an accounting surface within the river aquifer. The river aquifer consists of permeable, partly saturated sediments and sedimentary rocks that are hydraulically connected to the Colorado River so that water can move between the river and the aquifer in response to withdrawal of water from the aquifer or differences in water-level elevations between the river and the aquifer. The accounting surface represents the elevation and slope of the unconfined static water table in the river aquifer outside the flood plain and reservoirs that would exist if the river were the only source of water to the river aquifer. Maps at a scale of 1:100,000 show the extent and elevation of the accounting surface from the area surrounding Lake Mead to Laguna Dam near Yuma, Arizona.

Arizona, California, Nevada, Utah↗

USGS1995

Streamflow analysis of the Apalachicola, Pearl, Trinity, and Nueces River basins, southeastern United States

Annual mean streamflow and annual minimum and maximum daily mean streamflows were compared with associated annual index precipitation for sites on the main channels and tributaries of four major rivers that discharge directly into the Gulf of Mexico. Long- and short-term precipitation trends were identified for selected streamflow stations with at least 40 years of record. Long-term temporal trends in annual mean streamflow and annual maximum daily mean streamflow to the Gulf were not identified from the Apalachicola River Basin for the period of record studied. Annual mean and maximum streamflow to the Gulf increased with time from the Pearl River Basin and decreased from the Trinity River Basin. Annual mean streamflow showed varied trends and annual maximum streamflow decreased from the Nueces River Basin. Annual minimum streamflow to the Gulf increased in all of the basins studied. The annual index precipitation associated with the most downstream station also increased during the periods of record studied in all four of the basins. Short-term trends in streamflow generally corresponded to trends in associated annual index precipitation for each station. For some streamflow stations in the Trinity River Basin, short-term trends in annual minimum streamflow increased while annual maximum streamflow decreased. Total reported surface-water withdrawals have increased more than fourfold in the Trinity River Basin since 1940. Surface-water withdrawals from the Trinity River Basin in 1988 represent about one-fourth of the annual mean streamflow near the mouth. Total withdrawals increased more than eightfold in the Nueces River Basin since 1940. Surface-water withdrawals from the Nueces River Basin in 1988 represent about one-third of the annual mean streamflow near the mouth. Effects of selected reservoirs on streamflow in the four basins also were studied. Predicted peak streamflow into the Gulf from the Apalachicola River was about 23 percent less for the 50- year peak streamflow after reservoir construction. Although one large reservoir was built on the Pearl River and many reservoirs have been built on the Trinity River and its tributaries, peak streamflow into the Gulf of Mexico from these rivers has not been affected during the past 50 years. Estimates from a water-budget analysis showed that the annual mean streamflow to the Gulf from the Nueces River was reduced by about 24 percent from 1985 through 1990 as a result of filling and evaporation at Choke Canyon Reservoir.

Apalachicola, Nueces, Pearl, and Trinity River bas↗

USGS1996

Streamflow characteristics of the Waccamaw River at Freeland, North Carolina, 1940-94

Streamflow characteristics of the Waccamaw River at Freeland, North Carolina, for the period 1940-94 were described and compared to stream- flows in the adjacent Lumber River Basin. Precipitation in the two basins was about equal for the study period. During 1940-63, stream- flows in the Waccamaw and Lumber Rivers were essentially identical relative to average conditions. The flow regime from the late 1950's to the early 1980's was distinctly wetter than the flow regimes which immediately preceded and followed this period. Following 1963, droughts in the Waccamaw Basin seem to have been less severe than in the Lumber Basin, and the annual 1-, 7-, and 30-day low flows exhibited a slightly increasing trend in the Waccamaw River. Mean daily flow in the Wacca- maw River at the 90-percent exceedance level (low flows) during 1985- 94, a relatively dry period, was very nearly equal to flows at the same exceedance level for 1970-79, the wettest 10-year period between 1940 and 1994. Prior to the 1980's, flows per unit drainage area in the Waccamaw Basin were generally less than those in the Lumber Basin, but after 1980, the opposite was true. There is an increasing trend in the difference between Waccamaw River and Lumber River high flows, primarily as a result of increases in Waccamaw River high flows. On average, streamflow in the Waccamaw River consisted of 53.3 percent base flow, but base flow accounted for 70.6 percent of the total flow in the Lumber River, which is more typical of Coastal Plain streams. The ratio of base flow to runoff in the Waccamaw River may have changed relative to that in the Lumber River in the late 1970's. There was greater variability in Waccamaw River streamflow than in Lumber River flow, and flow variability in the Waccamaw River may have increased slightly during 1985-94.

North Carolina↗

USGS1999

Relations of surface-water quality to streamflow in the Raritan River basin, New Jersey, water years 1976-93

Relations of water quality to streamflow were determined for 18 water-quality constituents at 21 surface-water stations within the drainage area of the Raritan River Basin for water years 1976-93. Surface-water-quality and streamflow data were evaluated for trends (through time) in constituent concentrations during high and low flows, and relations between constituent concentration and streamflow, and between constituent load and streamflow, were determined. Median concentrations were calculated for the entire period of study (water years 1976-93) and for the last 5 years of the period of study (water years 1989-93) to determine whether any large variation in concentration exists between the two periods. Medians also were used to determine the seasonal Kendall’s tau statistic, which was then used to evaluate trends in concentrations during high and low flows. Trends in constituent concentrations during high and low flows were evaluated to determine whether the distribution of the observations changes through time for intermittent (nonpoint storm runoff) or constant (point sources and ground water) sources, respectively. Highand low-flow trends in concentrations were determined for some constituents at 13 of the 21 water-quality stations; 8 stations have insufficient data to determine trends. Seasonal effects on the relations of concentration to streamflow are evident for 16 of the 18 constituents. Negative slopes of relations of concentration to streamflow, which indicate a decrease in concentration at high flows, predominate over positive slopes because of the dilution of instream concentrations by storm runoff. The slopes of the regression lines of load to streamflow were determined in order to show the relative contributions to the instream load from constant (point sources and ground water) and intermittent sources (storm runoff). Greater slope values indicate larger contributions from storm runoff to instream load, which most likely indicate an increased relative importance of nonpoint sources. The slopes of load-to-streamflow relations along a stream reach that tend to increase in a downstream direction indicate the increased relative importance of contributions from storm runoff. The slopes of load-to-streamflow relations increase in the downstream direction for alkalinity at North Branch Raritan and Millstone Rivers, for some or all of the nutrient species at South Branch and North Branch Raritan Rivers, for hardness at South Branch Raritan River, for dissolved solids at North Branch Raritan River, for dissolved sodium at Lamington River, and for suspended sediment and dissolved oxygen at Millstone River. Likewise, the slopes of load-tostreamflow relations along a stream reach that tend to decrease in a downstream direction indicate the increased relative importance of point sources and ground-water discharge. The slopes of load-to-streamflow relations decrease in the downstream direction for dissolved solids at Raritan and Millstone Rivers; for dissolved sodium, dissolved chloride, total ammonia plus organic nitrogen, and total ammonia at South Branch Raritan, Raritan, and Millstone Rivers; for dissolved oxygen at North Branch Raritan and Lamington Rivers; for total nitrite at Lamington, Raritan, and Millstone Rivers; for total boron at South Branch Raritan and Millstone Rivers; for total organic carbon at North Branch Raritan River; for suspended sediment and total nitrogen at Raritan River; and for hardness, total phosphorus, and total lead at Millstone River.

New Jersey↗

USGS2000

Environmental and hydrologic overview of the Yukon River basin, Alaska and Canada

The Yukon River, located in northwestern Canada and central Alaska, drains an area of more than 330,000 square miles, making it the fourth largest drainage basin in North America. Approximately 126,000 people live in this basin and 10 percent of these people maintain a subsistence lifestyle, depending on the basin’s fish and game resources. Twenty ecoregions compose the Yukon River Basin, which indicates the large diversity of natural features of the watershed, such as climate, soils, permafrost, and geology. Although the annual mean discharge of the Yukon River near its mouth is more than 200,000 cubic feet per second, most of the flow occurs in the summer months from snowmelt, rainfall, and glacial melt. Eight major rivers flow into the Yukon River. Two of these rivers, the Tanana River and the White River, are glacier-fed rivers and together account for 29 percent of the total water flow of the Yukon. Two others, the Porcupine River and the Koyukuk River, are underlain by continuous permafrost and drain larger areas than the Tanana and the White, but together contribute only 22 percent of the total water flow in the Yukon. At its mouth, the Yukon River transports about 60 million tons of suspended sediment annually into the Bering Sea. However, an estimated 20 million tons annually is deposited on flood plains and in braided reaches of the river. The waters of the main stem of the Yukon River and its tributaries are predominantly calcium magnesium bicarbonate waters with specific conductances generally less than 400 microsiemens per centimeter. Water quality of the Yukon River Basin varies temporally between summer and winter. Water quality also varies spatially among ecoregions.

Alaska, British Columbia↗

USGS1955

Floods of April 1952 in the Missouri River basin

The floods of April 1952 in the Milk River basin, along the Missouri River from the mouth of the Little Missouri River to the mouth of the Kansas River, and for scattered tributaries of the Missouri River in North and South Dakota were the greatest ever observed. The damage amounted to an estimated $179 million. The outstanding featur6 of the floods was the extraordinary peak discharge generated in the Missouri River at and downstream from Bismarck, N. Dak., on April 6 when a large ice jam upstream from the city was suddenly released. Inflow from flooding tributaries maintained the peak discharge at approximately the same magnitude in the transit of the flood across South Dakota; downstream from Yankton, S. Dak., attenuation of the peak discharge was continuous because of natural storage in the wide flood plains. The outstanding characteristic of floods in the Milk River basin was their duration--the flood crested at Havre, Mont., on April 3 and at Nashua, Mont.. on April 18. The floods were caused by an abnormally heavy accumulation of snow that was converted into runoff in a few days of very warm weather at the end of March. The heaviest water content of the snow pack at breakup was in a narrow arc extending through Aberdeen, S. Dak., Pierre, S. Dak.. and northwestward toward the southwest corner of North Dakota. The water content in part of this concentrated cover exceeded 6 inches. The winter of 1951-52, which followed a wet cold fall that made the ground impervious, was one of the most severe ever experienced in South Dakota and northern Montana. Depths of snow and low temperatures combined to produce, at the end of March, one of the heaviest snow covers in the history of the Great Plains. The Missouri River ice was intact upstream from Chamberlain, S. Dak., at the end of March, and the breakup of the ice with inflow of local runoff was one of the spectacular features of the flood. Runoff from the Yellowstone River combining with the flood pouring from the Little Missouri River caused the Missouri River to crest at an all-time high at Elbowoods, N. Dak., on April 4. As this crest moved downstream to Bismarck, its intensity was increased by the alternate storing and release of ice jams plus the inflow from the Knife River. The crest discharge of 500,000 cfs came at Bismarck at 6 p. m. on April 6. following a very sharp rise from 80,000 cfs at 11 a.m. Overflow occurred along the Missouri River from Elbowoods to the mouth with high damage to cities. farmland, and installations located in the flood plain. Cleanup and repair operations following the flood continued for many weeks. Few of the flooded farms produced a crop during 1952. This report presents detailed records of stage and discharge for the flood period on the Missouri River and tributaries from Fort Peck. Mont., to the mouth. Information on damages and river stages collected by other agencies is also presented.

Missouri River Basin↗

USGS2020

QCam: sUAS-based doppler radar for measuring river discharge

The U.S. Geological Survey is actively investigating remote sensing of surface velocity and river discharge (discharge) from satellite-, high altitude-, small, unmanned aircraft systems- (sUAS or drone), and permanent (fixed) deployments. This initiative is important in ungaged basins and river reaches that lack the infrastructure to deploy conventional streamgaging equipment. By coupling alternative discharge algorithms with sensors capable of measuring surface velocity, streamgage networks can be established in regions where data collection was previously impractical or impossible. To differentiate from satellite or high-altitude platforms, near-field remote sensing is conducted from sUAS or fixed platforms. QCam is a Doppler (velocity) radar mounted and integrated on a 3DR © Solo sUAS. It measures the along-track surface velocity by spot dwelling in a river cross section at a vertical where the maximum surface velocity is recorded. The surface velocity is translated to a mean-channel (mean) velocity using the probability concept (PC), and discharge is computed using the PC-derived mean velocity and cross-sectional area. Factors including surface-scatterer quality, flight altitude, propwash, wind drift, and sample duration may affect the radar-returns and the subsequent computation of mean velocity and river discharge. To evaluate the extensibility of the method, five science flights were conducted on four rivers of varying size and dynamics and included the Arkansas River, Colorado (CO), USA (two events); Salcha River near Salchaket, Alaska (AK), USA; South Platte River, CO, USA; and the Tanana River, AK, USA. QCam surface velocities and river discharges were compared to conventional streamgaging methods, which represented truth. QCam surface velocities for the Arkansas River, Salcha River, South Platte River, and Tanana River were 1.02 meters per second (m/s) and 1.43 m/s; 1.58 m/s; 0.90 m/s; and 2.17 m/s, respectively. QCam discharges (and percent differences) were 9.48 (0.3%) and 20.3 cubic meters per second (m 3 /s) (2.5%); 62.1 m 3 /s (−10.4%); 3.42 m 3 /s (7.3%), and 1579 m 3 /s (−18.8%). QCam results compare favorably with conventional streamgaging and are a viable near-field remote sensing technology that can be operationalized to deliver real-time surface velocity, mean velocity, and river discharge, if cross-sectional area is available.

Remote Sensing↗

USGS2005

Historical and current perspectives on fish assemblages of the Snake River, Idaho and Wyoming

The Snake River is the tenth longest river in the United States, extending 1,667 km from its origin in Yellowstone National Park in western Wyoming to its union with the Columbia River at Pasco, Washington. Historically, the main-stem Snake River upstream from the Hells Canyon Complex supported at least 26 native fish species, including anadromous stocks of Chinook salmon Oncorhynchus tshawytscha, steelhead O. mykiss, Pacific lamprey Lampetra tridentata, and white sturgeon Acipenser transmontanus. Of these anadromous species, only the white sturgeon remains in the Snake River between the Hells Canyon Complex and Shoshone Falls. Today, much of the Snake River has been transformed into a river with numerous impoundments and flow diversions, increased pollutant loads, and elevated water temperatures. Current (1993-2002) fish assemblage collections from 15 sites along the Snake River and Henrys Fork contained 35 fish species, including 16 alien species. Many of these alien species such as catfish (Ictaluridae), carp (Cyprinidae), and sunfish (Centrarchidae) are adapted for warmwater impounded habitats. Currently, the Snake River supports 19 native species. An index of biotic integrity (IBI), developed to evaluate large rivers in the Northwest, was used to evaluate recent (1993-2002) fish collections from the Snake River and Henrys Fork in southern Idaho and western Wyoming. Index of biotic integrity site scores and component metrics revealed a decline in biotic integrity from upstream to downstream in both the Snake River and Henrys Fork. Two distinct groups of sites were evident that correspond to a range of IBI scores-an upper Snake River and Henrys Fork group with relatively high biotic integrity (mean IBI scores of 46-84) and a lower Snake River group with low biotic integrity (mean IBI scores of 10-29). Sites located in the lower Snake River exhibited fish assemblages that reflect poor-quality habitat where coldwater and sensitive species are rare or absent, and where tolerant, less desirable species predominate. Increases in percentages of agricultural land, total number of diversions, and number of constructed channels were strongly associated with these decreasing IBI scores.

American Fisheries Society Symposium↗

USGS2013

Snake River fall Chinook salmon life history investigations: Annual report 2011 (April 2011 - March 2012)

Executive Summary Chapter One – This chapter was published in the Transactions of the American Fisheries Society in 2012. We conducted a three-year radiotelemetry study in the lower Snake River to answer the questions: do fall Chinook salmon juveniles pass dams during winter when bypass systems and structures designed to prevent mortality are not operated; does downstream movement rate vary annually, seasonally, and from reservoir to reservoir; and, what are some of the factors that contribute to annual, seasonal, and spatial variation in downstream movement rate? Fall Chinook salmon juveniles moved downstream up to 169 km and fast enough (7.5 km/d) such that large percentages (up to 93%) of the fish passed one or more dams during winter. Mean downstream movement rate varied annually (9.2-11.3 km/d), increased from winter (7.5 km/d) to spring (16.4 km/d), and increased (6.9-16.8 km/d) as fish moved downstream from reservoir to reservoir. Fish condition factor at tagging explained some of the annual variation ( P ≤ 0.01) in downstream movement rate, whereas water particle velocity ( P ≤0.0001) and temperature ( P ≤0.0001) explained portions of the seasonal variation. An increase in migrational disposition as fish moved downstream helped explain the spatial variation ( P =0.05-0.07). The potential cost of winter movement might be reduced survival due to turbine passage when the bypass systems and spillway passage structures are not operated. Efforts to understand and increase passage survival of winter migrants in large impoundments might help to rehabilitate some imperiled anadromous salmonid populations. Chapter Two – Natural juvenile fall Chinook salmon in the Snake and Clearwater rivers exhibit two life history strategies. “Ocean-type” fish migrate out to the ocean in their first summer of life as subyearlings, but “reservoir-type” fish delay seaward migration during the summer, and some overwinter in reservoirs before continuing their migration the following spring as yearlings. Earlier emerging fish produced in the Snake River tend to adopt the ocean-type life history whereas many of the later emerging fish from the Clearwater River tend to adopt the reservoirtype life history. The underlying cause of the reservoir-type life history is poorly understood, but we believe there may be link to physiological development. We used traditional markers of the parr-smolt transformation (smoltification), including gill Na + /K + -ATPase activity and thyroid hormone levels, along with gene expression microarrays to assess the development of ocean-type juvenile fall Chinook salmon and then compared it to that of juvenile fall Chinook salmon from the Clearwater River. We showed that parr in the Snake River are physiologically distinct from actively-migrating smolts but smolts migrating early and late in the summer and fall are physiologically similar. Juvenile fall Chinook salmon collected from the Clearwater River were similar in size to early-migrating smolts in the Snake River but were most physiologically similar to Snake River parr. Genes differentially expressed between Snake River parr and smolts and between fish from the Clearwater River and smolts from the Snake River were involved in the cell cycle, steroid metabolism and other metabolic pathways, and DNA repair and packaging. Many of the genes differentially expressed in these comparisons had expression patterns that correlated with gill Na + /K + -ATPase activity, suggesting that they were related to smoltification and migration status. Chapter Three – Natural subyearlings produced in the Clearwater River are exposed to cool (~10-12°C) temperatures when water is released from Dworshak Reservoir for summer flow augmentation. Total dissolved gas (TDG) levels range from 100-110% in the lower Clearwater iv River. When fish move into the Snake River, they encounter temperatures up to 24°C at the surface which have the potential to incur gas bubble disease (GBD) in fish as dissolved gases in their bodies expand under warmer temperatures. This may result in both direct and indirect mortality, but this situation has been little studied. We conducted laboratory experiments to examine subyearling mortality rates and incidence and severity of GBD in fish that were moved between waters that varied in TDG and temperature. Fish experienced significant mortality only at temperatures of 25°C, which increased with exposure time. However there was no significance difference in mortality between fish acclimated to 100% TDG and 110% TDG. Fish that died did show signs of GBD. Generally, signs of GBD such as bubbles in the lateral line and unpaired fins were higher in fish acclimated at 110% TDG than in fish acclimated at 100% TDG, but there were few trends related to exposure temperature. Field measurements of TDG showed that TDG ranged from about 100% to 122.5% at some locations. Generally, TDG fluctuated daily, up to 8% during August and early September, and was highest late in the afternoon and lowest in the early morning. Laboratory results and field monitoring demonstrated that emigrating juvenile salmon can potentially be at risk from elevated temperatures, TDG, and GBD albeit to an unknown extent, which may increase their vulnerability to predation. Chapter Four – We conducted monthly beam trawling in Lower Granite and Little Goose reservoirs to describe the seasonal abundance of benthic epifauna that are potentially important as prey to juvenile fall Chinook salmon. The predominant taxa collected were Siberian prawns, the opossum shrimp Neomysis mercedis , and the amphipod Corophium sp. Prawns were relatively abundant at shallow sites in both reservoirs in June, but were more abundant at deep sites in lower and middle reservoir reaches in autumn. Prawn densities were commonly <0.2/m2. Prawn length-frequency data indicated that there were at least two size classes. Juvenile prawns present in shallow water more often than adult prawns, which were generally only found in deep water by autumn. Ovigerous prawns had an average of 171 eggs, which represented about 11.5% of their body weight. Limited diet analyses suggested that prawns consumed Corophium , Neomysis , and aquatic insects. Neomysis dominated all catches both in terms of abundance and biomass, and they were more abundant in Lower Granite compared to Little Goose reservoir. Neomysis were more abundant at shallow sites than at deep sites. Corophium were present in our collections but were never abundant, probably because our trawl was not effective at capturing them. The caloric content of prawns (4,782 Kcal), Neomysis (4,962 Kcal), and Corophium (4,926 Kcal) indicates that these prey would be energetically profitable for juvenile salmon. Subyearling fall Chinook salmon prey heavily on Neomysis and Corophium at times, but the importance of prawns as prey is uncertain.

Oregon, Washington↗

USGS2017

Snake River Fall Chinook Salmon life history investigations

Predation by nonnative fishes is one factor that has been implicated in the decline of juvenile salmonids in the Pacific Northwest. Impoundment of much of the Snake and Columbia rivers has altered food webs and created habitat favorable for species such as Smallmouth Bass Micropterus dolomieu . Smallmouth Bass are common throughout the Columbia River basin and have become the most abundant predator in lower Snake River reservoirs (Zimmerman and Parker 1995). This is a concern for Snake River Fall Chinook Salmon Oncorhynchus tshawytscha (hereafter, subyearlings) that may be particularly vulnerable due to their relatively small size and because their main-stem rearing habitats often overlap or are in close proximity to habitats used by Smallmouth Bass (Curet 1993; Tabor et al. 1993). Concern over juvenile salmon predation spawned a number of large-scale studies to quantify its effect in the late 1980s, 1990s, and early 2000s (Poe et al. 1991; Rieman et al. 1991; Vigg et al. 1991; Fritts and Pearsons 2004; Naughton et al. 2004). Smallmouth Bass predation represented 9% of total salmon consumption by predatory fishes in John Day Reservoir, Columbia River, from 1983 through 1986 (Rieman et al. 1991). In transitional habitat between the Hanford Reach of the Columbia River and McNary Reservoir, juvenile salmon (presumably subyearlings) were found in 65% of Smallmouth Bass (>200 mm) stomachs and comprised 59% of the diet by weight (Tabor et al. 1993). Within Lower Granite Reservoir on the Snake River, Naughton et al. (2004) showed that monthly consumption (based on weight) ranged from 5% in the upper reaches of the reservoir to 11% in the forebay. However, studies in the Snake River were conducted soon after Endangered Species Act (ESA) listing of Snake River Fall Chinook Salmon (NMFS 1992). During this time, Fall Chinook Salmon abundance was at an historic low, which may explain why consumption rates were relatively low compared to those from studies conducted in the Columbia and Yakima rivers where abundance was higher (e.g., Tabor et al. 1993; Fritts and Pearsons 2004). We speculate that predation on subyearlings by Smallmouth Bass in the Snake River may have increased in recent years for several reasons. Since their ESA listing, recovery measures implemented for Snake River Fall Chinook salmon have resulted in a large increase in the juvenile population (Connor et al. 2013). Considering that subyearlings probably now make up a larger portion of the forage fish population, it is plausible they should make up a large portion of Smallmouth Bass diets. Second, migrating subyearlings delay downstream movement in the transition zones of the Clearwater River and Snake River for varying lengths of time (Tiffan et al. 2010), which increases their exposure and vulnerability to predators. Spatial overlap in locations of Smallmouth Bass and subyearlings that died during migration provides support for this (Tiffan et al. 2010). Finally, the later outmigration of subyearlings from the Clearwater River results in their presence in Lower Granite Reservoir during the warmest summer months when predation rates of Smallmouth Bass should be highest. In 2016, we focused our efforts on Smallmouth Bass predation in Lower Granite Reservoir downstream of the transition zones and the confluence area where we worked during 2012–2015. Similar to past years, our first objective was to quantify Smallmouth Bass consumption rates of subyearlings, determine relative bass abundance, and describe bass diets. In addition, Tiffan et al. (2016a) posited that predation risk to subyearlings may be higher in shoreline habitats that are more suitable for Smallmouth Bass and lower in shoreline habitats that are more suitable for subyearlings. To test this hypothesis, our second objective examines the relationship between Smallmouth Bass predation of subyearlings and habitat suitability.

Idaho, Washington↗

USGS2022

Wind River subbasin restoration: Annual Report of U.S. Geological Survey activities January 2020 through December 2020

We sampled juvenile wild Steelhead Trout Oncorhynchus mykiss in headwater streams of the Wind River, WA, to characterize population attributes and investigate life-history metrics, particularly migratory patterns, and early life-stage survival. We used passive integrated transponder (PIT) tagging and a series of instream PIT-tag interrogation systems (PTISs) to track juveniles and adults. The Wind River subbasin is considered a wild Steelhead refuge by Washington Department of Fish and Wildlife (WDFW). No hatchery Steelhead Trout have been released in the Wind River subbasin since 1997, and hatchery adults are estimated at less than one percent of spawners in most years. Over twenty years of Steelhead Trout status and trend monitoring and research in the subbasin is contributing to understanding of population response to numerous restoration actions in the subbasin, including removal of Hemlock Dam from Trout Creek in 2009, which had an outdated adult ladder and contributed to increased water temperatures reducing performance of juvenile Steelhead Trout. Data from our study, and companion work by Washington Department of Fish and Wildlife, are contributing to Bonneville Power Administration’s (BPA) Research, Monitoring, and Evaluation (RM&E) Program Strategy of Fish Population Status Monitoring (https://www.cbfish.org/ProgramStrategy.mvc/Index). Specifically, this work addresses the substrategies of 1) Assessing the Status and Trends of Diversity of Natural Origin Fish Populations and Uncertainties Research regarding differing life histories of a wild Steelhead Trout population, 2) Assessing the Status and Trend of Adult Natural Origin Fish Populations, and 3) Monitoring and Evaluating the Effectiveness of Tributary Habitat Actions Relative to Environmental, Physical, or Biological Performance Objectives. During summer and fall 2020, we PIT-tagged 1,415 Steelhead parr (age-0 and age-1) in the Trout Creek and upper Wind River watersheds. Recaptures and detections of PIT-tagged Steelhead Trout parr happened through repeat headwater sampling, smolt trap operations, and instream PTISs and Columbia River PIT-tag detection infrastructure. Throughout the year, we maintained a series of six instream PTISs to monitor movement of tagged Steelhead Trout parr, smolts, and adults, providing data to population assessments, and life-cycle research and modeling. Detection data from PIT-tagged adult Steelhead Trout at PTISs allow assessment of adult escapement to tributary watersheds within the Wind River subbasin. Adult Steelhead Trout detection efficiency estimates at our primary PTIS in Trout Creek have been greater than 92 percent during eight of the past nine years and have exceeded 90% at our primary PTIS in the Wind River the past three years. Adult escapement estimates to tributary watersheds are helping evaluate the efficacy of the 2009 removal of Hemlock Dam from rkm 2.0 of Trout Creek. The dam had potential negative effects on Steelhead Trout populations in Trout Creek due to hydrologic impairment, increased temperatures, and adult passage issues. Hemlock Dam was laddered for adult passage, but not to modern standards, which likely resulted in avoidance by some adult Steelhead Trout. We continue to improve our PTISs in the Wind River subbasin. The improvements in siting and addition of grid power to the upper Wind River PTIS (site code WRU, rkm 27.6) during 2016 and 2017, and the addition of the Mine Reach site (site code MIN, rkm 36.0) have much improved PIT-tagged fish monitoring in the upper Wind River watershed. The paired PTIS design in the upper Wind River watershed (sites WRU and MIN), matches that in the Trout Creek watershed (sites TRC and TC4) and will allow comparisons of Steelhead Trout population metrics between the two watersheds as response to Hemlock Dam removal continues and future restoration efforts occur in Trout Creek. We installed two new PTISs during 2020. Both were installed downstream of our primary interrogation sites on Trout Creek and in the mainstem Wind River. We hope the two new sites will provide interrogations information that will allow us to better estimate detection efficiencies of downstream moving juvenile Steelhead Trout at the primary interrogation sites. The additional interrogations will be particularly important for those fish tagged with 9-mm PIT tags as less information from downstream locations is available from them. These sites and other status and trend data will allow evaluation of further planned restoration within the watershed, particularly that proposed for the headwaters of Trout Creek. Detections at the instream PTISs have demonstrated trends of age-0 and age-1 parr emigration from natal areas during summer and fall, in addition to the expected movement of parr and smolts in spring. We have estimated that from 15 to 51% of parr tagged as age-0 fish in headwater areas make downstream migrations at age 1 for additional rearing during both spring and fall. We have estimated that up to 27% of Steelhead Trout parr, tagged as age-1 fish, make downstream migrations during fall. These findings raise questions about where parr most successfully rear and whether migrations are density or habitat quality driven. Broader monitoring programs would give a more comprehensive understanding of juvenile Steelhead Trout production and rearing and productivity contribution. Repeat sampling at consistent locations in the subbasin has enabled assessment of juvenile Steelhead Trout growth patterns. Growth rates (relative change in weight) of age-0 PITtagged parr during summer were similar across the subbasin but lower for age-1 parr in the Trout Creek watershed than the upper Wind River watershed. Yearly relative growth for parr tagged at age-0 is similar across the subbasin. Non-native Brook Trout Salvelinus confluentus are present in the subbasin, chiefly the Trout Creek watershed, and repeat sampling has allowed us to index their prevalence. Mean percent-of-catch that is Brook Trout, at four sample sites in Trout Creek, has declined from the period 1998 – 2003 to the period 2011 – 2020. Percent-of-catch and number of Brook Trout at the Trout Creek sites from 2011 through 2020 declined, though both metrics increased in 2018. Evaluation and planning of restoration efforts are critical to ensure efficient use of resources. Assessing Steelhead Trout life history variation in the Wind River subbasin will inform research and tracking of many populations and help inform habitat restoration and water allocation planning. Movement of Steelhead Trout parr from natal areas to other rearing areas raises questions regarding juvenile abundance, origin, and habitat use within watersheds. Improved PTISs and focused PIT tagging of age-0 and age-1 Steelhead Trout parr allow investigation of such questions. Increasingly detailed viable salmonid population information, such as that provided by PIT-tagging and instream PTIS networks like those in the Wind River can provide data to inform fisheries policy and management and understand life-history strategies and limiting factors. Such efforts also provide assessment of long-term effects of habitat restoration actions such as the removal of Hemlock Dam on Trout Creek, and the proposed Stage-0 restoration effort for upper Trout Creek, which would be a large-scale effort to reset sections of stream within their floodplain, restoring connectivity and interaction with surrounding landscape.

Washington↗

USGS2026

Wind River subbasin restoration: Annual report of U.S. Geological Survey activities January 2024 through December 2024

We sampled juvenile wild Oncorhynchus mykiss (Steelhead Trout) in headwater streams of the Wind River, Washington, to characterize population attributes and investigate life-history metrics, particularly migratory patterns, and early life-stage survival. Additionally, this sampling provides an index of abundance of non-native Brook Trout Salvelinus confluentus . We used passive integrated transponder (PIT) tagging and a series of instream PIT-tag interrogation systems (PTISs) to track juveniles and adults. The Wind River subbasin is considered a wild Steelhead refuge by Washington Department of Fish and Wildlife (WDFW). No hatchery Steelhead Trout have been released in the Wind River subbasin since 1997, and hatchery adults are estimated at less than one percent of spawners in most years. Over 25 years of Steelhead Trout status and trend monitoring and research in the subbasin is contributing to understanding of population response to numerous restoration actions in the subbasin, including removal of Hemlock Dam from Trout Creek in 2009, which had an inadequate adult ladder and contributed to increased water temperatures, to near lethal levels for salmonids. Data from our study, and companion work by WDFW, are contributing to the Columbia Basin Fish and Wildlife Program (2009) Research, Monitoring, and Evaluation (RM&E) Strategy of Fish Population Status Monitoring. Specifically, this work addresses the sub-strategies of 1) Assessing the Status and Trends of Diversity of Natural Origin Fish Populations and Uncertainties Research regarding differing life histories of a wild Steelhead Trout population, 2) Assessing the Status and Trend of Adult Natural Origin Fish Populations, and 3) Monitoring and Evaluating the Effectiveness of Tributary Habitat Actions Relative to Environmental, Physical, or Biological Performance Objectives. During summer and fall 2024, we PIT-tagged 2,075 Steelhead Trout parr (age-0 and age-1), in the Trout Creek and upper Wind River watersheds. Age-0 and age-1 parr were at high abundance due to strong spawner numbers in 2023 and 2024 (Estimate of 932 in 2023; and a moderate number of spawners in 2024 though an estimate is not available at this time; 24-year median = 619; Charlie Cochran, WDFW Fish Biologist, personal commun., 2025). An additional 100 parr (age-0 and age-2 or older) were tagged to provide fish for estimating detection efficiencies at PTISs. Steelhead Trout parr were recaptured and detected through repeat headwater sampling, smolt trapping, instream PTISs and Columbia River mainstem PIT-tag detection. We maintained and upgraded six instream PTISs to detect PIT-tagged Steelhead Trout parr, smolts, and adults, providing data for population assessments, and life-cycle research. Detection data from PIT-tagged adult Steelhead Trout at our four primary PTISs allow assessment of adult escapement to tributary watersheds within the Wind River subbasin. Most adult Steelhead detected were tagged by WDFW at an adult trap in the lower Wind River and some as smolts at screw traps. Adult Steelhead Trout detection efficiency estimates at our primary PTIS in Trout Creek have been greater than 99 percent during eight of the past ten years and have exceeded 97% at our primary PTIS in the Wind River during nine of the past ten years. Adult escapement estimates to tributary watersheds are helping evaluate the efficacy of the 2009 removal of Hemlock Dam from rkm 2.0 of Trout Creek. Detections at the instream PTISs have shown trends of age-0 and age-1 Steelhead Trout parr emigration from natal areas during summer and fall, in addition to the expected movement of parr and smolts in spring. Our data suggest that most fish from a cohort that migrate downstream will do so at age-1 for additional rearing in the subbasin. We have estimated that from 15% to 56% of parr tagged as age-0 fish in headwater areas make downstream migrations at age-1 for additional rearing (median = 29%). We have estimated that from 1% to 27% of Steelhead Trout parr, tagged as age-1 fish, make downstream migrations during fall (median = 3.5%): this is especially pronounced in the upper Wind River portion of the watershed (median 10%). These findings raise questions about parr rearing habitat and whether migrations are density- or habitat-quality driven, and answers to such questions are long-term goals of this study as active and passive habitat restoration occurs. Repeat sampling at sites in the subbasin within and between years has enabled assessment of juvenile Steelhead Trout growth patterns. Growth rates (relative change in weight) of age-0 PIT-tagged parr during summer have been similar across the subbasin, though slightly lower in the Trout Creek watershed (Trout Creek sites, 0.57 - 1.25%/day, Wind River sites = 0.94 – 2.48%/day). Summer growth rates have been lower for age-1 parr in the Trout Creek watershed than the upper Wind River watershed (Trout Creek sites, = 0.03 - 0.14%/day, Wind River sites = 0.05 – 0.19%/day). Yearly relative growth was similar across the subbasin for both age-0 and age-1 tagged parr. During 2024 range of mean daily relative change in weight from the previous year for age-0 tagged fish was: Trout Creek sites = 0.96 – 1.41%/day, Wind River sites = 0.80 – 1.30 %/day; and for age1 tagged fish was: Trout Creek sites = 0.37 - 0.50 %/day, Wind River sites = no age-1 tagged recaptures. Non-native Brook Trout are present in the subbasin, chiefly the Trout Creek watershed. Mean percent-of-catch that is Brook Trout, at four sample sites in Trout Creek, has declined from the period 1998 – 2003 to the period 2011 – 2024 (range of decrease = 19 - 82%). Percent-of-catch (of 64 samples, 52 < 10%; 3 > 20%) and number of Brook Trout at the Trout Creek sites from 2011 through 2024, though variable, have generally declined. Habitat restoration evaluation efforts are critical to ensure efficient use of money and resources but require long-term monitoring of population metrics. Detailed viable salmonid population and life-history data, such as that provided by PIT-tagging and instream PTIS networks inform fisheries policy and management and enable assessment of long-term effects of habitat restoration actions such as the removal of Hemlock Dam on Trout Creek and proposed major instream habitat restoration in the upper Wind River.

Washington↗

USGS2019

Distribution and movement of steelhead and anglers in the Clearwater River, Idaho

Steelhead Oncorhynchus mykiss is a species that is of high economic value that supports popular sport fisheries across the Pacific Northwest. The Clearwater River in Idaho provides a trophy steelhead fishery, and it is home to both wild- and hatchery-origin steelhead. To manage the fishery effectively, information is needed about the spatial and temporal overlap of wild and hatchery steelhead in the Clearwater River, as well as the activity of anglers. We conducted a radiotelemetry study to describe the distribution of steelhead and their final fate in the Clearwater River, and creel surveys were used to describe the distribution of anglers. In total, 289 wild (Potlatch River and Lochsa River) and hatchery (from Dworshak National Fish Hatchery and South Fork Clearwater River) steelhead were radio-tagged at Lower Granite Dam, 51 river kilometers (rkm) downstream from the mouth of the Clearwater River. Fish were monitored upon their entry into the Clearwater River by using mobile tracking surveys (boat and vehicle) and stationary antennas. The majority of wild and hatchery steelhead arrived in the Clearwater River in the fall with the exception of those from the Lochsa River, which arrived in the fall and following spring. Average daily movement of the fish was minimal (range = 0.3–4.7 km/d) and dependent on water temperature and flow. The fates of wild and hatchery steelhead varied. Fish returned to spawning grounds, were harvested by anglers (hatchery fish only), or had unknown fates. Both wild and hatchery steelhead returned at high rates to their natal tributaries and release locations. No straying was observed in either group; however, occasions when steelhead have overshot their natal tributaries and release locations were documented. Spatial and temporal overlap of the distributions of wild and hatchery steelhead was minimal. The distribution of anglers overlapped with that of hatchery steelhead in the fall, winter, and spring. The distributional overlap of anglers and wild steelhead was minimal and largely occurred in September in the lower Clearwater River. This suggests that the Clearwater River has a highly compartmentalized fishery and that current fishing regulations in the Clearwater River are providing for a diversity of angling opportunities while conserving wild steelhead and offering harvest of hatchery fish. The results from this study have important implications for the conservation and management of wild and hatchery steelhead.

Idaho↗

USGS2024

Use of otolith microchemistry to determine natal origin for Silver Carp Hypophthalmichthys molitrix in the lower Mississippi River basin

Silver Carp ( Hypophthalmichthys molitrix ) populations have established and expanded throughout the lower Mississippi River basin (LMRB). Information pertaining to Silver Carp population mixing among rivers within the LMRB is lacking. Documented relations between Silver Carp otolith and river water barium (Ba) and strontium (Sr) microchemical signatures may enable estimation of origins of Silver Carp in the LMRB. Replicate water samples and otoliths from 308 Silver Carp were collected from the Cache, Arkansas, White, Yazoo, St. Francis, L’Anguille, and Mississippi rivers, and Merrisach Lake (situated along a canal connecting the lower reaches of the Arkansas and White rivers) within the LMRB. Water and carp otolith microchemical signatures exhibited consistent differences among water bodies. A classification and regression tree model exhibited 80% accuracy when assigning carp collected from the White, Arkansas, and Mississippi rivers based on fish-water microchemical signatures. Model accuracy decreased as smaller rivers were incorporated into models. Predicted natal origin based on otolith microchemical signatures suggested the White River (43%) and the lower Mississippi River (39%) were the likely origins for ~ 82% of the Silver Carp sampled. Despite the prevalence of adult Silver Carp within the Arkansas River system, fewer (18%) appeared to have originated there compared to the White and Mississippi rivers. Long-term water sampling and additional isotopic measurements may refine analyses to better determine the relative contributions of Silver Carp from the smaller river systems. Population mixing of Silver Carp among tributary rivers appears to be common within the LMRB, and removal efforts may benefit from evaluating the magnitude of fish movement and connectivity among rivers.

lower Mississippi River basin↗

USGS2008

Sources and fate of nitrate in the Illinois River Basin, Illinois

We conducted a two-year investigation into the sources and fate of nitrate (NO3-) in the Illinois River from the Chicago area to the river's confluence with the Mississippi River. Samples from waterways in the Chicago area (Des Plaines River and the Sanitary and Ship Canal) had relatively high concentrations of nitrogen (N) species and NO3- isotopic compositions indicative of treated wastewater (TWW). Downstream of the Brandon Road Lock and Dam, NO3- in tributaries discharging to the Illinois River primarily comes from tiles draining row crops. Nitrate isotopic signatures from these tributaries as well as drain tiles were indicative of synthetic fertilizer and/or soil organic matter (SOM) at various stages of denitrification. Nitrate-N concentrations generally decreased in the Illinois River with distance from the Chicago area primarily due to dilution. The decrease in NO3-N concentrations was especially conspicuous during the summer, when there is minimal discharge from drain tiles and NO3-N concentrations in the tributaries were low. In August 2005, when conditions were very dry, NO3-N concentrations decreased from 7.4 mg/L in the Chicago area to less than 1 mg/L near where the Illinois River discharges to the Mississippi River. The isotopic composition of NO3- in water samples from the Illinois River were a mixture of three end members: (1) fertilizer and/or SOM in drain tile water, typically showing the least amount of denitrification, (2) fertilizer and/or SOM in deeper ground water, showing the highest degree of denitrification, and (3) TWW. There was seasonal variability, depending on the volume of water flowing in the Illinois River. During high flow periods, river water samples plotted closest to those of tile drain samples; during low flow periods, a greater influence of TWW was observed in the isotopic composition. A subset of summer samples from the Chicago waterways had isotopic values plotting near and within the domain that characterizes manure and sewage. Nitrate in the Chicago area is primarily derived from TWW, with its isotopic signature evident downstream at least as far as Pekin during most of the year and all the way to the Mississippi River during periods of low flow. Denitrification occurs predominantly in groundwater between and away from drain tiles, although there is evidence that in-stream denitrification and/or biological uptake of NO3- occurs in the Peoria Lake reach of the Illinois River, at least during periods of low flow in the summer. We calculated that the river was losing about half of its NO3-N load in Peoria Lake in August 2005 (a period of very low flow), at a rate of about 7500 kg/day.

Journal of Hydrology↗

USGS2003

Flood plain and channel dynamics of the Quinault and Queets Rivers, Washington, USA

Comparison of historic channel migration rates, modern planform conditions, and overall sediment, wood, and flow conditions and interactions for the Quinault River and Queets River in the western Olympic Peninsula, Washington, reveals decadal- to century-scale interactions between gravel-bed channels and forested flood plains in temperate maritime environments. The downstream alluvial portions of these two rivers can be divided into three reaches of different slope, flow, sediment, and wood regimes: (i) the upper Quinault River is aggrading behind Lake Quinault, a natural lake that traps most sediment and wood transported from the Olympic Mountain headwaters. (ii) The lower Quinault River, downstream of Lake Quinault, transports only sediment and wood derived from reworking of flood-plain deposits and contributed from valley margins. (iii) The Queets River has unimpeded movement of sediment and water from the mountainous headwaters to the Pacific Ocean. Measurements of channel planform characteristics and historic migration rates and patterns show that these three reaches have correspondingly distinct channel and flood-plain morphologies and dynamics. The aggrading and sediment-rich upper Quinault River has the widest flood plain, widest active channel, greatest number of low-flow channels and flanking gravel bars, and an average channel migration rate of 12.7±3.3 m/year between 1900 and 1994. The comparatively sediment-poor lower Quinault River has the narrowest flood plain, narrowest active channel, and lowest channel migration rate (4.0±1.2 m/year); and most flow is through a single channel with few adjacent gravel bars. The Queets River has attributes intermediate between the lower and upper Quinault Rivers, including an average channel migration rate of 7.5±2.9 m/year. Flood-plain turnover rates are similar for all three reaches, with channels eroding the flood plain at the rate of about 0.2% of the flood-plain area per year, and with corresponding flood-plain half-lives of 300 to 500 years. Observations from this study and previous studies on the Queets River show that channel and flood-plain dynamics and morphology are affected by interactions between flow, sediment, and standing and entrained wood, some of which likely involve time frames similar to 200–500-year flood-plain half-lives. On the upper Quinault River and Queets River, log jams promote bar growth and consequent channel shifting, short-distance avulsions, and meander cutoffs, resulting in mobile and wide active channels. On the lower Quinault River, large portions of the channel are stable and flow within vegetated flood plains. However, locally, channel-spanning log jams have caused channel avulsions within reaches that have been subsequently mobile for several decades. In all three reaches, log jams appear to be areas of conifer germination and growth that may later further influence channel and flood-plain conditions on long time scales by forming flood-plain areas resistant to channel migration and by providing key members of future log jams. Appreciation of these processes and dynamics and associated temporal and spatial scales is necessary to formulate effective long-term approaches to managing fluvial ecosystems in forested environments.

Geomorphology↗

USGS2019

Birth and evolution of the Virgin River fluvial system: ∼1 km of post–5 Ma uplift of the western Colorado Plateau

The uplift history of the Colorado Plateau has been debated for over a century with still no unified hypotheses for the cause, timing, and rate of uplift. 40 Ar/ 39 Ar and K/Ar dating of recurrent basaltic volcanism over the past ∼6 Ma within the Virgin River drainage system, southwest Utah, northwest Arizona, and southern Nevada, provides a way to reconstruct paleoprofiles and quantify differential river incision across the boundary faults of the Colorado Plateau–Basin and Range boundary. We compare differential incision data with patterns of channel steepness, bedrock erodibility, basaltic migration, and mantle velocity structure to understand the birth and evolution of the Virgin River system. New detrital sanidine ages constrain the arrival of the Virgin River across the Virgin Mountains to less than 5.9 Ma. Virgin River incision rates and amounts show an eastward stair-step increase in bedrock incision across multiple N-S–trending normal faults. Using block incision values away from fault-related flexures, average bedrock incision rates are near zero since 4.6 Ma in the Lower Colorado River corridor, 23 m/Ma from 6.8 to 3.6 Ma in the Lake Mead block, 85 m/Ma from 3 to 0.4 Ma in the combined St. George and Hurricane blocks, and 338 m/Ma from 1 to 0.1 Ma in the Zion block. Steady incision within each block is documented by incision constraints that span these age ranges. We test two end-member hypotheses to explain the observed differential incision magnitudes and rates along the Virgin River system over the past ∼5 Ma: (1) as a measure of mantle-driven differential uplift of the Colorado Plateau relative to sea level; or (2) due to river integration across previously uplifted topography and differential rock types with down-dropping of Transition Zone blocks but no post–5 Ma uplift. We favor headwater uplift of the Colorado Plateau because basalt-preserved paleoprofiles indicate that eastern fault blocks have been the “active” blocks that moved upwards relative to western blocks with little base-level change of the lower Colorado River corridor in the past 4.6 Ma. Block-to-block differential incision adds cumulatively such that the Zion block (Colorado Plateau edge) has been deeply incised 880–1200 m (∼338 m/Ma) over the 2.6–3.6 Ma period of Hurricane fault neotectonic movement, which has a slip magnitude of 1100 m. Mantle-driven uplift is implicated by a strong correlation throughout the Virgin River drainage between high normalized channel steepness (k sn ) and low underlying mantle velocity, whereas there is a weaker correlation between high k sn and resistant lithologies. Basaltic volcanism has migrated northeastward at a rate of ∼18 km/Ma parallel to the Virgin River between ca. 13 and 0.5 Ma, also suggesting a mantle-driven mechanism for the combined epeirogenic uplift of the western Colorado Plateau, recurrent slip on its bounding faults, and headward propagation and differential incision of the Virgin River. Thus, we interpret the Virgin River to be a <5 Ma disequilibrium river system responding to ongoing upper-mantle modification and related basalt extraction that has driven ∼1 km of young (and ongoing) surface uplift of the western Colorado Plateau.

Arizona, Nevada, Utah↗