Use of Sediment Rating Curves and Optical Backscatter Data to Characterize Sediment Transport in the Upper Yuba River Watershed, California, 2001–03

U.S. Geological Survey Scientific Investigations Report 2005–5246 , published 2006.

U.S. Department of the Interior

P. Lynn Scarlett, Acting Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director
The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.

1 U.S. Geological Survey, California Water Science Center, 6000 J Street, Placer Hall, Sacramento, California 95819-6129

2 U.S. Geological Survey, Southwest Biological Science Center, 2255 North Gemini Drive, Flagstaff, Arizona 86001

3 U.S. Geological Survey, Pacific Science Center, 400 Natural Bridges Drive, Santa Cruz, California 95060. Now at Department of Geology and Geophysics, Boston College, 140 Commonwealth Ave., Chestnut Hill, Massachusetts 02467

Acronyms

CBDA
California Bay–Delta Authority
CBDA-ERP
California Bay–Delta Authority-Ecosystem Restoration Program
D84
the grain size representing 84 percent of the bed-surface material
EDI
equal discharge interval
EWI
equal-width increment
ERP
Ecosystem Restoration Program
g
gravitational acceleration
GCLAS
Graphical Constituent Loading Analysis System
h1
the portion of the flow depth attributed solely to skin friction
H2O2
hydrogen peroxide
ID
identification number
mi2
square mile
OBS
optical backscatter sensor
p value
the probability of error associated with accepting the predicted results as true
PInp
nonparametric prediction interval
Q
streamflow
RMS
root mean square
SSC
suspended-sediment concentration
SSC/V
suspended-sediment concentration/voltage
SDSZ
unpublished software documentation
U
mean velocity
U*
bed-shear velocity
USGS
U.S. Geological Survey
UYRSP
Upper Yuba River Studies Program
WY
water year

Abbreviations

NAD 27
Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27)
NGVD 29
Elevation is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29)
ft
foot
ft3/s
cubic foot per second
ft2/s
square foot per second
g/ft/s
gram per foot per second
in.
inch
m
meter
µm
micrometer
mi
mile
mm
millimeter
m2
square meter
mi2
square mile
Mya
million years ago
phi
unit of measure used in grain size analysis
r2
coefficient of determination
ton/day
ton per day
ton/mi2
ton per square mile
yd3
cubic yard

Abstract

Sediment transport in the upper Yuba River watershed, California, was evaluated from October 2001 through September 2003. This report presents results of a three-year study by the U.S. Geological Survey, in cooperation with the California Ecosystem Restoration Program of the California Bay–Delta Authority and the California Resources Agency. Streamflow and suspended-sediment concentration (SSC) samples were collected at four gaging stations; however, this report focuses on sediment transport at the Middle Yuba River (11410000) and the South Yuba River (11417500) gaging stations. Seasonal suspended-sediment rating curves were developed using a group-average method and non-linear least-squares regression. Bed-load transport relations were used to develop bed-load rating curves, and bed-load measurements were collected to assess the accuracy of these curves. Annual suspended-sediment loads estimated using seasonal SSC rating curves were compared with previously published annual loads estimated using the Graphical Constituent Loading Analysis System (GCLAS). The percent difference ranged from –85 percent to +54 percent and averaged –7.5 percent. During water year 2003 optical backscatter sensors (OBS) were installed to assess event-based suspended-sediment transport. Event-based suspended-sediment loads calculated using seasonal SSC rating curves were compared with loads calculated using calibrated OBS output. The percent difference ranged from +50 percent to –369 percent and averaged –79 percent.
The estimated average annual sediment yield at the Middle Yuba River (11410000) gage (5 tons/mi2) was significantly lower than that estimated at the South Yuba River (11417500) gage (14 tons/mi2). In both rivers, bed load represented 1 percent or less of the total annual load throughout the project period. Suspended sediment at the Middle Yuba River (11410000) and South Yuba River (11417500) gages was typically greater than 85 percent silt and clay during water year 2003, and sand concentrations at the South Yuba River (11417500) gage were typically higher than those at the Middle Yuba River (11410000) gage for a given streamflow throughout the three year project period. Factors contributing to differences in sediment loads and grain-size distributions at the Middle Yuba River (11410000) and South Yuba River (11417500) gages include contributing drainage area, flow diversions, and deposition of bed-material-sized sediment in reservoirs upstream of the Middle Yuba River (11410000) gage. Owing to its larger drainage area, higher flows, and absence of man-made structures that restrict sediment movement in the lower basin, the South Yuba River transports a greater and coarser sediment load.

Introduction

The upper Yuba River watershed is a heavily managed basin recovering from hydraulic gold mining that occurred in the mid 1800s to early 1900s. The Upper Yuba River Studies Program (UYRSP), a component of the California Bay–Delta Authority (CBDA) Ecosystem Restoration Program (ERP), is evaluating options for introducing spring-run Chinook salmon and steelhead trout upstream of Englebright Dam, which is located in the foothills of the northwestern Sierra Nevada, California (fig. 1). This report is one product of on-going studies by the U.S. Geological Survey (USGS) (Childs and others, 2003; Flint and others, 2004; Snyder and others, 2004a, 2004b, 2004c; Curtis and others, 2005), which provide a comprehensive analysis of sediment sources, transport, and storage in the upper Yuba River watershed. The USGS is also investigating water quality in the Yuba River watershed and sediment quality in Englebright Lake, with an emphasis on mercury contamination and bioaccumulation (Alpers and others, 2004; Slotten, 2004).
Figure 1Location of sediment and streamflow gaging stations, study area of the Upper Yuba River Studies Program (UYRSP), and the upper Yuba River watershed, California.
See table 1 for station names.
Location of sediment and streamflow gaging stations, study area of the Upper Yuba River Studies Program (UYRSP), and the upper Yuba River watershed, California.

Purpose and Scope

This study assesses sediment transport in the upper Yuba River watershed, using sediment rating curves and optical backscatter data, and along with the USGS Annual Water-Data Reports (Rockwell and others, 2001; Smithson and others, 2002; Friebel and others, 2003), provides baseline daily, annual, and event-based sediment-transport data for the upper Yuba River watershed. The sediment rating curves and OBS time series data were used to calibrate a watershed-scale sediment transport model (Flint and others, 2004) and to assess the magnitude and duration of sediment loads that may impact the viability of long-term fish-introduction strategies (Curtis and others, 2004). The rating curves provided a means to estimate annual sediment loads by using simulated historic streamflow from 1940 to 2000 (Flint and others, 2004). The estimated historic annual sediment loads were compared to downstream annual sedimentation rates in Englebright reservoir (Snyder and others, 2004c). In addition, the rating curves were used to estimate event-based sediment transport using 15-minute streamflow data, and these estimates were compared with estimates made using optical backscatter data. Sediment loads estimated using rating curves were compared with loads estimated using GCLAS (Rockwell and others, 2001; Smithson and others, 2002; Friebel and others, 2003), but are not intended to replace the previously published daily and annual loads.

Acknowledgments

Terry Mills and Rebecca Fris (CBDA-ERP) and the California Resources Agency assisted with project funding and contract management. Denis O’Halloran (USGS-Carnelian Bay, California) and Ned Andrews (USGS-Denver, Colorado) provided insightful discussions regarding sediment transport. Alan Mlodnosky (USGS-Marina, California), Carlin Dare (USGS-Menlo Park, California), Gary Schneider (USGS-Menlo Park, California), and Ryan Wooley (USGS-Menlo Park, California) completed the suspended-sediment-concentration and grain-size analyses. Sarah Yarnell (University of California, Davis), Michael Hunerlach (USGS-Sacramento, California), Donna Knifong (USGS-Sacramento, California), Michael Judd, and David Sparks assisted with the Shady Creek bed-load measurements.

Study Area

The Yuba River, a tributary to the Feather River in northern California, drains approximately 1,344 mi2 along the western slope of the Sierra Nevada (fig. 1). The study area is within the upper Yuba River watershed, which encompasses the area upstream of Englebright Lake and includes three tributaries: the North Yuba River, the Middle Yuba River, and the South Yuba River. A significant part of the Yuba River sediment load is deposited in New Bullards Bar Reservoir (Brown and Thorpe, 1947; Dendy and Champion, 1978), in Englebright Lake (Childs and others, 2003; Snyder and others, 2004b; Snyder and others, 2004c), and behind Log Cabin Dam and Our House Dam (Yuba County Water Agency, 1989). Because only wash-load-sized material (the finer part of the sediment load carried by streamflow) bypasses New Bullards Bar Reservoir on the North Yuba River, the focus of this study was on sediment transport solely within the Middle Yuba and South Yuba Rivers.
The upper Yuba River tributaries (North Yuba, Middle Yuba, and South Yuba Rivers) are steep, mountain drainages that flow through narrow, deeply incised canyons alternating between bedrock and alluvial reaches. Alluvial reaches store considerable volumes of sediment in the channel bed, active bars, and infrequent well-vegetated floodplains and terraces (Curtis and others, 2005). Bedrock reaches have minimal channel storage, although patchy alluvium may be found in deep pools or behind bedrock constrictions or large boulders. Large volumes of sediment, derived from upstream hydraulic-mining activities, are currently stored in several upland tributaries that flow into the Middle Yuba and South Yuba Rivers.

Climate, Precipitation, and Runoff

The study area has a mediterranean climate with hot, dry summers and cool, wet winters. Beginning in November, Pacific frontal systems bring winter precipitation into northern California, and approximately 85 percent of the annual precipitation falls between November and April. Mean annual precipitation ranges from 20 in. at Marysville at the western downstream end of the watershed (fig. 1) to more than 59 in. at the eastern margin of the watershed along the Sierra Nevada crest (Western Regional Climate Center, accessed November 8, 2004). Total precipitation at Englebright Lake was 24 in., 32 in., and 37 in. (California Data Exchange Center, accessed November 8, 2004) during water years 2001, 2002, and 2003, respectively. Average annual precipitation at Englebright Lake is 33 in.; therefore, water year 2001 was a dry year, 2002 was below average, and 2003 was above average.
Runoff in the study area is produced by winter storms from the Pacific, spring snowmelt, and occasional convective storms generated in the late summer or early autumn by subtropical air masses from the Gulf of Mexico (Kattleman, 1996). Peak flows can be as much as three orders of magnitude greater than base flows and annual runoff volumes can be as much as seven times greater in extremely wet years than those in critically dry years. Elevations between 4,000 to 6,000 ft in the study basin are susceptible to rain-on-snow events (California Department of Water Resources, 1966); these events have the greatest magnitude, duration, and ability to mobilize sediment. Notable runoff events (peak streamflows greater than 100,000 ft3/s) at the Yuba River below Englebright Dam (11418000) occurred during water years (WY) 1951, 1956, 1963, 1965, 1986, and 1997 (fig. 2). The timing of runoff throughout the study area is controlled to a considerable extent by a system of reservoirs and diversions (fig. 3).
Figure 2Annual peak streamflows measured from 1942 to 2003 for the gaging station on the Yuba River below Englebright Dam (YRE, 11418000) in the upper Yuba River watershed, California.
See table 1 for station name and location. Data source: http://nwis.waterdata.usgs.gov/, accessed November 8, 2004.
Annual peak streamflows measured from 1942 to 2003 for the gaging station on the Yuba River below Englebright Dam (YRE, 11418000) in the upper Yuba River watershed, California.
Figure 3AStream diversions and reservoir storage in the upper Yuba River watershed, California.
Source: Rockwell and others, 2001 http://water.usgs.gov/pubs/wdr/WDR-CA-01-4/
Stream diversions and reservoir storage in the upper Yuba River watershed, California.
Figure 3BStream diversions and reservoir storage in the upper Yuba River watershed, California.
Source: Rockwell and others, 2001 http://water.usgs.gov/pubs/wdr/WDR-CA-01-4/
Stream diversions and reservoir storage in the upper Yuba River watershed, California.

Geologic Setting

Bedrock in the study area is composed primarily of Paleozoic metasediments and metavolcanics (ShooFly and Calaveras Formations), Paleozoic and Mesozoic plutonic rocks (Bowman Lake batholith, Sierra Nevada batholith, and Yuba River pluton), and a Mesozoic ophiolite (Smartville Complex). Ridge tops typically are capped by Eocene auriferous sediments deposited by the ancestral Yuba River, Miocene-Pliocene rhyolites, rhyolitic sediments (Valley Springs Formation), and andesitic lahars (Mehrten Formation) (Saucedo and Wagner, 1992).
Cenozoic geologic history includes uplift and tilting of the Sierra Nevada and at least two Late Quaternary glaciations (Lindgren, 1911; Bateman and Wahrhaftig, 1966; Christensen, 1966; James and others, 2002). Uplift and tilting reorganized drainage networks and initiated a period of sustained channel incision. The modern Yuba River system began incising approximately 5 Mya (million years ago) (Wakabayashi and Sawyer, 2001). The easternmost portion of the basin was glaciated during the Quaternary, and the Middle Yuba River and South Yuba River drainages are mantled by till and glacial outwash deposited by Late Quaternary valley glaciers (James and others, 2002).

Hydraulic Mining History

Gold-bearing sediments, deposited by the ancestral Yuba River (Whitney, 1880; Lindgren, 1911; Yeend, 1974), were hydraulically mined during the California Gold Rush of the mid-to-late 1800s and again during a protracted period of licensed mining in the early 1900s. Hydraulic-mining involved directing high-pressure water cannons at exposures of Eocene gravel (fig. 4) and washing the excavated sediment slurry through mercury-laden sluice boxes (Bowie, 1905; May, 1970; Averill, 1976; Alpers and others, 2005). Hydraulic mine tailings were conveyed into adjacent watercourses, leading to dramatic increases in sediment loads and severe aggradation (Hall, 1880; Turner, 1891; Gilbert, 1917). Gilbert (1917) estimated that hydraulic-mining contributed approximately 682 million yd3 of sediment to Yuba River channels. In 1884, owing to downstream environmental effects, large-scale hydraulic-mining was ended by court injunction (Sawyer Decision). Licensed hydraulic-mining began in 1893 (Camenetti Act) and continued in the Yuba River basin until the 1930s. Presently, the abandoned hydraulic mine pits experience chronic hillslope erosion (Yuan, 1979) and, therefore, are considered a significant sediment source to upper Yuba River channels (Curtis and others, 2005).
Figure 4Hydraulic mining at Malakoff Diggings (circa 1876), located in the South Yuba River watershed, California.
Historic photograph taken by Carleton E. Watkins, Hearst Mining Collection, Bancroft Library, University of California at Berkeley.
Hydraulic mining at Malakoff Diggings (circa 1876), located in the South Yuba River watershed, California.
Extensive remobilization of stored hydraulic-mining sediment began as early as 1861 when severe winter storms delivered substantial volumes of sediment to the Central Valley. In 1941, the California Debris Commission built Englebright Dam to trap hydraulic-mining sediment mobilized within the upper Yuba River watershed. The majority of Middle Yuba River and South Yuba River mainstem channels have since recovered their pre-mining bed elevations, but significant volumes of hydraulic mining sediment remain stored in wide mainstem reaches and in smaller upland tributaries of these two rivers. Previous studies of the Yuba River and adjacent watersheds (Wildman, 1981; James, 1993; Curtis, 1999) indicate that these smaller tributaries are asymptotically incising toward pre-mining channel-bed elevations; therefore, remobilization of hydraulic-mining sediment continues to affect sediment yields from impacted basins.

Methods of Data Collection and Analysis

Streamflow measurements and suspended-sediment samples were collected at four upper Yuba River gaging stations (fig. 1; table 1): Middle Yuba River near North San Juan (USGS station ID 11410000), South Yuba River at Jones Bar near Grass Valley (USGS station ID 11417500), Yuba River below New Colgate Powerplant near French Corral (USGS station ID 11413700), and Yuba River below Englebright Dam near Smartville (USGS station ID 11418000). The Middle Yuba River (11410000) gage operated from 1911 to 1941 and from 2001 to present. The South Yuba River (11417500) gage operated from 1940 to 1948 and from 1959 to present. The Yuba River below New Colgate Powerplant (11413700) gage was established in 2001 but was abandoned in 2003 owing to a poor gaging record. The Yuba River below Englebright Dam (11418000) gage operated continually from 1941 to present. Daily records of streamflow and suspended-sediment loads for water years 2001, 2002, and 2003 are published in USGS Annual Water-Data Reports (Rockwell and others, 2001; Smithson and others, 2002; Friebel and others, 2003). Annual streamflow peaks as well as daily and 15-minute streamflow data are available at http://waterdata.usgs.gov/nwis/ .
Table 1 (View this table on a separate page.) Summary of streamflow and suspended-sediment measurements for four sites in the Upper Yuba River watershed, California, during water years 2001, 2002, and 2003.
[See figure 1 for station locations. Latitude and longitude are referenced to the North American Datum of 1927 (NAD 27). Elevation is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). EDI, equal-discharge interval; N, number of samples. mi2, square miles; ft, feet; ft3/s, cubic feet per second. —, gage discontinued because of poor rating]
       Water year 2001
       Suspended-sediment EDI samples (N)¹Minimum daily streamflow (ft³/s)Maximum daily streamflow (ft³/s))
     Drainage area (mi²)Elevation (ft)
          
Map identifierStation identifierGage nameLatitudeLongitude
MYG11410000Middle Yuba River near North San Juan39º23′39″121º05′02″1981,45019627150
SYG11417500South Yuba River at Jones Bar near Grass Valley39º17′32″121º06′13″3081,600194291,020
YRC11413700Yuba River below New Colgate Powerplant near French Corral39º19′50″121º11′34″71755098413,080
YRE11418000Yuba River below Englebright Dam near Smartville39º14′07″121º16′23″1,108279625982,280
          
  Water year 2002 Water year 2003  
  Suspended-sediment EDI samples (N)²Minimum daily streamflow (ft³/s)Maximum daily streamflow (ft³/s) Suspended-sediment EDI samples (N)³Minimum daily streamflow (ft³/s)Maximum daily streamflow (ft³/s) 
Map identifierStation identifier
MYG1141000015028906 152291,390 
SYG11417500154301,750 143412,990
YRC11413700106433,050  
YRE11418000365734,170 336296,940 

Suspended Sediment

Sampling and Concentration Analysis

Depth-integrated, single vertical and multi-vertical suspended-sediment samples were collected at upper Yuba River gaging stations following standard USGS procedures (Edwards and Glysson, 1999). Samples were collected at four gaging stations (Middle Yuba River, 11410000; South Yuba River, 11417500; Yuba River below New Colgate Powerplant, 11413700; and Yuba River below Englebright, 11418000) during water years 2001 and 2002 and at three gaging stations (11410000, 11417500, 11418000) during water year 2003. Suspended-sediment concentrations for all samples were measured at the USGS sediment laboratory in Marina, California, using methods described by Guy (1969). During water years 2001 through 2003, single vertical samples were collected 1 to 7 days per week, depending on hydrologic conditions, with increased frequency of sampling during periods of higher streamflow. Beginning in water year 2002, two sequential single vertical samples were collected during each visit and analyzed separately for concentration. Multi-vertical cross-section samples, collected approximately monthly, were used to determine a coefficient to account for discrepancies between the mean suspended-sediment concentration of the single vertical samples and that of the entire cross section. Multi-vertical sampling consisted of collecting a single vertical sample, a set of 12 equal-discharge-increment (EDI) samples across the channel, followed by another single vertical sample. The concentrations of these 14 samples were analyzed separately. Comparisons of the single vertical samples with the cross-section samples indicate that flows generally were well-mixed with respect to sediment at all four gaging stations. The average difference between concurrent single vertical and EDI samples was 13 percent. Although streamflow samples for suspended-sediment analysis were collected primarily during low and moderate flows, we infer the mean discharge-weighted suspended-sediment concentration of all single vertical samples are representative of the channel cross section, thus making use of a coefficient unnecessary.

Storm Sampling

Storm sampling at the Middle Yuba River (11410000) and South Yuba River (11417500) gages enabled characterization of changes in suspended-sediment concentrations and grain-size distributions over the duration of four discrete storm hydrographs during water year 2003. Storms were chosen to represent four different times during the wet season (November, December, February, and March). The November storm was the first runoff event of the wet season and the other three runoff events were typical winter storms. The protocol for storm sampling included collection of single vertical suspended-sediment samples at 1- to 2-hour intervals during daylight hours and collection of at least one sequential pair of grain-size samples per day, which enabled characterization of the rising limb, peak, and falling limb of each storm hydrograph.

Grain-Size Analysis of Suspended Sediment

Replicate sets of suspended-sediment samples were collected from three of the upper Yuba River gaging stations (Middle Yuba River, 11410000; South Yuba River, 11417500; and Yuba River below Englebright Dam, 11418000) during storm sampling for detailed grain-size analyses. Two sequential sets of depth integrated, multi-vertical, equal-discharge-interval (EDI) suspended-sediment samples were collected at five centroids across the channel cross section. One set of samples was analyzed at the USGS sediment laboratory in Marina, California. A second set of samples was analyzed at the USGS Coastal and Marine Geology laboratory in Menlo Park, California. Both laboratories used standard sieve methods described by Guy (1969) for grain size analysis of the sand-sized fraction and results were similar. However, sample preparation and the results for sediment smaller than 0.063 mm differed between the two laboratories. The Marina Laboratory removed organic material (using H2O2 [hydrogen peroxide]) only from the sand-sized fraction, and the less than 0.63-mm sized fraction is reported. The Menlo Park Laboratory removed the organic material from the full sample and completed detailed analyses of the less than 0.063-mm fraction. Both laboratories used hexametaphosphate to disperse sediment smaller than 0.063 mm, but the Menlo Park Laboratory used ultrasound dispersal techniques also to further disperse the less than 0.063-mm sized fraction.
At the Menlo Park Laboratory, sediment smaller than 0.063 mm was analyzed using a Coulter LS 100Q laser-diffraction particle-size analyzer. Each sample was run through the Coulter instrument three times; the reported size distribution is the average of the three runs. Grain-size statistics were calculated using software (SDSZ; McHendrie and Madison, 1989, unpublished software documentation) that interpolates the size distribution at 0.5 phi increments.

Suspended-Sediment Rating Curves

Suspended-sediment transport is governed by sediment supply and the capacity of a stream to transport the available sediment. In some cases, such as alluvial rivers, streamflow and sediment supply tend to vary together such that the suspended-sediment concentration at a given location can be characterized using sediment rating curves, which relate transport of suspended sediment to streamflow. For cases when streamflow and sediment supply do not vary together, suspended-sediment concentration cannot be characterized by streamflow alone. In these cases, separate sediment rating curves must be developed for different supply conditions. Varying supply conditions occur primarily as a function of season in the Middle Yuba and South Yuba Rivers and justify development of separate suspended-sediment rating curves, as described below.
The relation between suspended-sediment concentration and streamflow at the four upper Yuba River gaging stations is shown in figure 5 A-D (also see Appendix 1 for complete data set shown in figure 5 A-D). Significant scatter in the concentration–streamflow relations indicates differences in sediment supply conditions attributable to seasonal and natural variability. Lack of precipitation during summer and fall months results in low base streamflow (for example, 25 ft3/s), which allows fine sediment to settle and accumulate in deep pools. During the first significant fall runoff event, called the first flush, significant amounts of easily transportable fine sediment are scoured from pools and eroded from hillslopes. Although hillslope erosion rates throughout the upper Yuba River watershed are relatively low compared with erosion rates for rapidly eroding hillslopes such as those in the Pacific Northwest, rilling, gullying, and mass wasting occur throughout the study area (Curtis and others, 2005).
Figure 5ABRelation of suspended-sediment concentration to instantaneous streamflow by season for the four gaging stations in the upper Yuba River watershed, California. A, Middle Yuba River (11410000). B, South Yuba River (11417500).
Relation of suspended-sediment concentration to instantaneous streamflow by season for the four gaging stations in the upper Yuba River watershed, California. A, Middle Yuba River (11410000). B, South Yuba River (11417500).
Figure 5CDRelation of suspended-sediment concentration to instantaneous streamflow by season for the four gaging stations in the upper Yuba River watershed, California. C, Yuba River below New Colgate Powerplant (11413700). D, Yuba River below Englebright Dam (11418000).
Relation of suspended-sediment concentration to instantaneous streamflow by season for the four gaging stations in the upper Yuba River watershed, California. C, Yuba River below New Colgate Powerplant (11413700). D, Yuba River below Englebright Dam (11418000).
Seasonal variability in the supply of suspended sediment is clearly evident when peak streamflow and associated suspended-sediment concentrations for first flush and snow melt conditions are compared. Samples collected from the upper Yuba River during the first flush generally have high suspended-sediment concentrations with low associated streamflow. For example, peak suspended-sediment concentrations in November 2002, and associated streamflow (shown in parentheses), were 134 mg/L (280 ft3/s) at the South Yuba River (11417500) gage and 100 mg/L (58 ft3/s) at the Middle Yuba River (11410000) gage (concentrations are averages for duplicate samples listed in Appendix 1a,b). Conversely, significant runoff from snowmelt occurs during the spring, resulting in high baseflows. Samples collected during snowmelt conditions have low suspended-sediment concentrations but high associated streamflow, indicating supply-limited conditions. For example, suspended-sediment concentrations during peak snowmelt conditions in May 2003, and associated streamflow, were 22 mg/L (1,930 ft3/s) at the South Yuba River (11417500) gage and 7 mg/L (260 ft3/s) at the Middle Yuba River (11410000) gage (concentrations are averages for duplicate samples listed in Appendix 1a,b).
Natural variability also influences the concentration–streamflow relation owing to processes such as depletion or rejuvenation of suspendable-sized sediment or to spatial variations in precipitation intensity and runoff throughout tributary and mainstem channel networks. Variability in the concentration–streamflow relation may also be caused by errors during sample collection and by corruption of samples during shipping or laboratory analyses.
Although there are numerous methods for developing rating curves, the most commonly used function for sediment rating curves is a power function,
(1)
SSC=aQb
where SSC is suspended-sediment concentration (mg/L), Q is streamflow (ft3/s), and a and b are regression coefficients (Walling, 1977; Asselman, 2000; Horowitz, 2002). Power functions were defined and regression coefficients were fit using non-linear, least-squares regression. Suspended-sediment concentrations at the Yuba River below New Colgate Powerplant (11413700) (fig. 5C) and Yuba River below Englebright Dam (11418000) (fig. 5D) gaging stations are influenced by management of New Bullards Bar Reservoir and Englebright Lake. Because there are no systematic relations between suspended-sediment concentrations and streamflow at the Yuba River below New Colgate Powerplant (11413700) and Yuba River below Englebright Dam (11418000) gaging stations, regression analyses were completed only on samples collected at the Middle Yuba River (11410000) (fig. 5A) and South Yuba River (11417500) (fig. 5B) gages, which have significant scatter but show a general increase in suspended-sediment concentration with increasing streamflow.
Most of the suspended-sediment samples were collected under low to moderate streamflow conditions (fig. 5); thus, regression analyses on these data are strongly influenced by the large number of measurements made during low streamflow conditions. The low-streamflow bias was removed from these data using a group average method, which results in a better defined slope for the upper end of the rating curve (Glysson, 1987). Removal of bias is an extremely important consideration because a slight error in the slope of the upper end of a sediment rating curve can generate significant error in predictions of suspended-sediment concentration, and may result in considerable error in calculations of sediment load.
Seasonal variability dramatically influences sediment supply and transport in the upper Yuba River watershed. A single suspended-sediment concentration rating curve that represents average conditions cannot represent these varying conditions. Therefore, a series of group-average sediment rating curves were established for the Middle Yuba River (11410000) and South Yuba River (11417500) gages that describe average (all data), summer/fall, first flush, winter, and spring snowmelt conditions. Prior to regression analysis, the arithmetic mean of suspended-sediment concentration was determined for several small ranges of Q, and an outlier threshold was established whereby suspended-sediment concentration values outside two standard deviations were excluded from the analysis. This improved the skewness of the data set and resulted in an approximate normal distribution. The average suspended-sediment concentration was plotted against the associated average streamflow value for each streamflow bin. Both variables were transformed to log 10 and a power function was fit through the group average data using non-linear least squares regression. The accuracy of the suspended-sediment rating curves was assessed using summary statistics and 95-percent confidence bounds.

Optical Backscatter

Schoellhamer and Wright (2003) demonstrated that optical backscatter sensors (OBS) can be used to predict suspended-sediment concentration in rivers if particle size and sediment color remain fairly constant. The sensors, developed and tested by Downing and others (1981), emit infrared light that is reflected by suspended particles in the water column. A series of photodiodes positioned around the emitter of the OBS detects any backscatter, and then an empirical calibration is used to convert the output voltage of the sensor into a suspended-sediment concentration. Calibration of the output voltage to suspended-sediment concentration can vary significantly with particle size and color (Conner and De Visser, 1992; Levesque and Schoellhamer, 1995; Sutherland and others, 2000) and biofouling can result in significant loss of data. Therefore, optical sensors must be cleaned regularly and calibrated using field data on a site-specific basis to determine if the effects of particle size and color influence sensor calibration for a given location.
Continuously recording OBSs were installed at the Middle Yuba River (11410000) and South Yuba River (11417500) gages to provide a 15-minute time series record of suspended-sediment concentration. The sensors were calibrated using depth-integrated, single vertical suspended-sediment samples that were analyzed for suspended-sediment concentration and percent fine-grained sediment (less than 0.063 mm) to assess the effects of grain size on the OBS output voltages. Because the OBS data can display non-constant variance, a linear calibration equation was determined using a robust, nonparametric, repeated median method originally developed for OBSs deployed in San Francisco Bay (Buchanan and Ruhl, 2000, 2001, 2002; Buchanan and Ganju, 2003, 2004). In addition, a prediction interval and a 95-percent confidence interval were calculated for each calibration equation to assess the goodness-of-fit.
The repeated median method (Siegel, 1982) calculates slope in a two-part process. First, for each point (X,Y), the median of all possible “point i” to “point j” slopes is calculated
(2)
for each point (X,Y), the median of all possible “point i” to “point j” slopes is calculated
The calibration slope is calculated as the median of ßi
(3)
slope=beta1=median
The calibration intercept is calculated as the median of all possible intercepts using the calibration slope
(4)
intersept=beta0=median(Y1-beta1X1)
The final linear calibration equation is
(5)
Y=beta1X+beta0
The nonparametric prediction interval (PInp) (Helsel and Hirsch, 1992, p. 76) contains one standard deviation (68.26 percent) of the calibration data set and represents essentially the same error prediction limits as the root mean square (RMS) error of prediction in ordinary least-squared regression. However, the PInp, unlike the RMS error of prediction, frequently is not symmetrical about the regression line. Asymmetry about the regression line is a result of the distribution of the data set; thus, the PInp may be reported as +9 to –16 mg/L. The PInp is calculated by computing and sorting, from least to greatest, the residuals for each point. Then, based on the sorted list of residuals,
(6)
nonparametric prediction interval=the residual value
Ŷ is the residual value, n is the number of data points, and α is the confidence level of 0.6826.
To calculate the confidence interval, all possible point-to-point slopes are sorted in ascending order. On the basis of the confidence interval desired, 95 percent for the purposes of this report, the ranks of the upper and lower bounds are calculated as follows:
(7)
a prediction interval to calibrate equation to assess the goodness of fit
(8)
a 95-percent confidence interval to calibrate equation to assess the goodness of fit
where Ru is the rank of the upper bound slope, Rl is the rank of the lower bound slope, and n is the number of samples. To establish the 95-percent confidence interval, the ranks calculated above are rounded to the nearest integer and the slope associated with each rank in the sorted list is identified.

Bed Load

Bed Material Grain-Size Analysis

For the purpose of developing bed-load rating curves, bed-surface samples were collected at Middle Yuba River (11410000) and South Yuba River (11417500) gages and at three locations along Shady Creek (figs. 1, 6). Pebble counts, made using the method described by Wolman (1954), were used to determine the surface grain-size distribution at the Shady Creek sites, whereas volumetric bed-material samples, collected using methods outlined by Milhous (1973), were used to determine the surface grain-size distribution at Middle Yuba River (11410000) and South Yuba River (11417500) gages.
Volumetric bed-material samples required excavation of the largest particle exposed on the channel bed. Although there were boulder-sized particles (greater than 256 mm) on the channel bed, only particles less than or equal to 128 mm were collected because particles larger than this could not easily be measured. Bed material was sampled volumetrically from a 0.25-m2 area to a level corresponding roughly to the bottom of the hole that was created when the largest particle was removed. Because small samples are systematically biased toward fine-grained sediment (Ferguson and Paola, 1997), we used a technique that increased the total sample volume, thus improving the sampling of particles larger than 64 mm. As sediment was shoveled into four 5-gallon buckets, all the particles greater than 64 mm were removed and hand sieved using a hand-held size analyzer and the less-than-64-mm sediment deposited in the buckets. We assumed that the particle-size distribution of the less-than-64-mm sediment in the four buckets was equal and completed further grain-size analyses of the less-than-64-mm fraction using sediment from a single bucket, which is an important consideration when sediment must be transported to a laboratory facility for sieving of the less-than-11 mm particles. The less-than-64-mm sediment from one bucket was sun-dried and field sieved at 0.5 phi intervals that ranged from 64 to 11 mm. Particles smaller than 11 mm were transported to a USGS sediment lab located in Sacramento, California, where they were oven-dried and laboratory sieved at 0.5 phi intervals ranging from 11 to 0.063 mm. Church and others (1987) recommend much larger sample sizes than were collected in this study. The suggested sample size would have required earth-moving equipment. For this study, the added time and expense were not justifiable.
Figure 6Location of bed-load sampling sites and cross-section bed-load transport locations along Shady Creek in the upper Yuba River watershed, California.
Location of bed-load sampling sites and cross-section bed-load transport locations along Shady Creek in the upper Yuba River watershed, California.

Bed-Load Rating Curves

To compute total sediment transport at the Middle Yuba River (11410000) and the South Yuba River (11417500) gages, bed-load transport had to be estimated. Regression relations between measured bed-load transport and streamflow could not be developed because logistics and expense precluded collection of bed-load measurements on the Middle Yuba and South Yuba Rivers. Therefore, bed-load transport rates were predicted using an empirical relation that relates sediment transport to the hydraulic conditions of the channel and to the sediment available for transport on the bed.
A single representative grain size was used in early studies (Meyer-Peter and Müller, 1948) to determine bed-load rating relations; consequently, these relations cannot account for different grain sizes moving at different rates. More recent bed-load relations can be used to predict transport rates for many individual grain sizes (Parker and others, 1982; Parker, 1990) but are limited to grain sizes larger than 2.0 mm. Using a series of flume experiments Wilcock and others (2001) concluded that small proportions of sand can cause nonlinear increases in bed-load transport, thereby causing predictions of greater bed-load transport rates. These flume data were used to develop an empirical mixed-size bed-load transport relation (Hopkins model; Wilcock and Crowe, 2003).
Bed-load transport rates were calculated for a range of streamflow values using the Hopkins model, which was developed from 48 observations of flow, transport, and bed-surface grain size (Wilcock and others, 2001). The 48 experimental runs spanned a four-fold range in streamflow (volumetric water discharge per unit width = 0.32 ft2/s to 1.39 ft2/s) and a 6 order-of-magnitude range in total sediment transport (0.0007 to 2,977 g/ft/s). Sediment used in the flume experiments were sand and gravel mixtures with gravel sizes ranging from 2.0 to 64 mm and sand sizes ranging from 0.2 to 2.0 mm. The proportion of sand in the sediment mixtures ranged from 6.2 to 34.3 percent, and the proportion of surface sand was measured following each experimental flume run and varied from 0.1 to 48 percent.
It is commonly advised that sediment transport models be applied only under conditions similar to those for which the model was developed. At the Middle Yuba River (11410000) gage, South Yuba River (11417500) gage, and Shady Creek sites, the streamflows of interest ranged from 18 to 4,800 ft3/s, which equates to unit streamflows of 2.2 ft2/s to 28.0 ft2/s. Although application of the Hopkins model for the upper Yuba River sites requires significant extrapolation beyond the maximum measured unit streamflow (1.39 ft2/s) in the empirical data set of the model, the mean daily unit streamflow at the Middle Yuba River (11410000) and South Yuba River (11417500) gages exceeded this value (1.39 ft2/s) only about 5 percent of the time. Granted the percentage of the annual bed load transported at these higher flows was likely much greater than 5 percent; however, bed load was not measured and therefore the percentage of bed load transport represented by the empirical dataset could not be determined. However, the percentage of sand in surface samples of bed material collected at the Middle Yuba River (11410000) gage, South Yuba River (11417500) gage, and at the Shady Creek sites ranged from 1.7 to 3.4 percent, which is within the range of the surface sand proportions in the empirical data set of the model.
The Hopkins model requires estimates of the surface grain-size distribution, water-surface slope, and shear velocities associated with the streamflow of interest. Laboratory analyses of bed material from the Middle Yuba River (11410000) and South Yuba River (11417500) gage sites and pebble counts (Wolman, 1954) at the Shady Creek sites were used to define surface grain-size distributions (fig. 7). Water-surface slopes were determined from longitudinal surveys of water-surface elevations measured using a surveyor’s transit level and a stadia rod along 500 ft of channel distance. Water-surface slope and surface grain-size distributions were assumed to be stationary for the range of streamflow analyzed.
Figure 7Cumulative percentage of the grain-size distribution of bed-surface material for two bed-load sampling sites located in Shady Creek and gaging stations on the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California.
Cumulative percentage of the grain-size distribution of bed-surface material for two bed-load sampling sites located in Shady Creek and gaging stations on the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California.
Methods used to estimate bed-shear velocities warrant a detailed explanation. Bed-shear stress can be partitioned into skin friction, the portion of stress that is exerted on individual grains and thus responsible for transport, and form drag attributable to large roughness elements, such as bedforms, boulders, bedrock outcrops, or large trees within the active channel. When applying a transport predictor such as the Hopkins model, only the skin-friction portion of bed-shear stress should be used to compute bed-shear velocities. Because bed-shear stresses in the upper Yuba River include a significant component of form drag, this term was removed before computing the shear velocities used in the Hopkins model. Skin friction was estimated using a form of the Einstein-Keulegan relation defined for a mixture of bed particles (Andrews, 1983)
(9)
U /U*= 2.5*ln (3.7 h1 / D84)
(10)
U* = (g h1 S) ½
where U is mean velocity, U* is bed-shear velocity, h1 is the portion of the flow depth attributed solely to skin friction, D84 is the grain size representing 84 percent of the bed-surface material, g is gravitational acceleration, and S is water-surface slope. Estimates of skin friction (bed-shear velocity minus the form-drag component) for a range of streamflows (0 to 5,000 ft3/s) were calculated by solving both sides of equation 9 for h1 iteratively using EXCEL Solver. In the absence of form drag, h1 = h; thus, h1 represents a hypothetical flow depth that can be used to estimate bed-shear velocities attributable solely to skin friction. Calculation of h1 required estimates of U, S, and D84 for a range of streamflows (0 to 5,000 ft3/s). Mean velocities (U) for the range of streamflows were estimated using mean velocity and streamflow relations (fig. 8), whereas slope (S) and D84 were estimated using field data. At the Middle Yuba River (11410000) gage, channel geometry changes between the low (wading site) and high (bridge site) streamflow measurement sites necessitated development of two separate velocity-streamflow relations (fig. 8). The high-flow relation was used to develop the Middle Yuba River (11410000) gage bed-load rating curve.
Figure 8Mean velocity and streamflow relations for gaging stations on the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California.
Note that streamflow measurements were collected at two sites near the Middle Yuba River gaging station: a wading site during low flows and at a bridge site during higher flows.
Mean velocity and streamflow relations for gaging stations on the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California.

Shady Creek Bed-Load Measurements

Bed-load samples collected on Shady Creek (a tributary to the South Yuba River) were used to assess the accuracy of the bed-load rating curves developed using the Hopkins model. Concurrent streamflow and bed-load measurements were collected at two locations along Shady Creek (fig. 6) using standard sampling techniques (Edwards and Glysson, 1999).
Single equal-width increment (EWI) samples were collected using a BL-84 cable-operated bed-load sampler at the Old Hwy 49 Bridge site and a BLH-84 hand-held sampler at the Rust Pit wading site (fig. 6). Both samplers have a 3-square-inch entrance nozzle and an area expansion ratio (ratio of nozzle exit area to entrance area) of 1.40. Samples were collected at the midpoints of evenly spaced verticals and sampling times at each vertical were equal. This allowed composite samples to be prepared for laboratory analyses. The bed-load samples were oven dried, weighed, and sieved at 0.5 phi intervals that ranged from 0.063 to 180 mm. Bed-load discharge (tons/day) was calculated as
(11)
qbi = k (M / T)
where qbi is the bed-load transport rate (tons/day); k is a conversion factor, based on the width of the sampler nozzle (0.381 for 3-in. nozzles used here) used to convert grams/second into tons/day; M is total mass of the bed-load sample (grams); and T is the total time the sampler was on the channel bed (seconds).

Results

Suspended Sediment

Storm Sampling

Storm sampling provided information regarding the timing of suspended-sediment concentration and streamflow peaks as well as information about varying grain-size distributions during storm events. Storm hydrographs, suspended-sediment concentrations, and percent sand are shown in figure 9A-D. Sediment sampling missed the November 2002 streamflow peak (fig. 9A); however, several sediment peaks that arrived prior to the storm peak were sampled and are characteristic of abundant sediment supply during first flush conditions. During the December 2002 storm event, the peak in suspended-sediment concentration coincided with the peak in streamflow (fig. 9B). We inferred that this was indicative of an abundant sediment supply during transport-limited winter storm conditions. During the February 2003 storm, the peaks in suspended-sediment concentration and streamflow coincided at the South Yuba River gage, again inferred to represent winter storm conditions, but the peak in suspended-sediment concentration was delayed at the Middle Yuba River (11410000) gage (fig. 9C). During the March 2003 storm, the peak in suspended-sediment concentrations arrived approximately 3 hours earlier than the peak in streamflow at the Middle Yuba River (11410000) gage and 6 hours earlier than the streamflow peak at the South Yuba River (11417500) gage (fig. 9D). The early arrival of sediment peaks indicated a limited supply of sediment. For the most part, concentrations of sand change systematically over the storm hydrographs with the lowest percentage of sand on the rising limb, greater percentages on the falling limb, and the highest percentages at the peak, indicating some hysteresis in sand concentrations.
Figure 9AInstantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, November 2002.
X's denote the date and time of samples analyzed for percent sand, and there are no grain-size data from the February 2003 event at Middle Yuba River gage.
Instantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, November 2002.
Figure 9BInstantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, December 2002.
Note that the inset in 9B displays suspended-sediment concentration samples collected during the December 2002 storm peak, X’s denote the date and time of samples analyzed for percent sand, and there are no grain-size data from the February 2003 event at Middle Yuba River gage.
Instantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, December 2002.
Figure 9CInstantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, February 2003.
X’s denote the date and time of samples analyzed for percent sand, and there are no grain-size data from the February 2003 event at Middle Yuba River gage.
Instantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, February 2003.
Figure 9D Instantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, March 2003.
X’s denote the date and time of samples analyzed for percent sand, and there are no grain-size data from the February 2003 event at Middle Yuba River gage.
 Instantaneous streamflow, suspended-sediment concentrations, and percent sand of suspended sediment during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California, March 2003.
Another observation made during storm sampling was of anomalously high suspended-sediment concentrations at the Middle Yuba River (11410000) gage on December 16, 2002 (see inset figure 9B). Significant volumes of sediment are stored behind Log Cabin Dam and Our House Dam (fig. 1), which require periodic dredging (Yuba County Water Agency, 1989). During large runoff events, these facilities discharge water over their spillways, and previously impounded sediment may be scoured and conveyed downstream resulting in elevated suspended-sediment concentrations at the Middle Yuba River (11410000) gage. Log Cabin Dam spilled again during the March 2003 storm sampling, but the impact of the spill was less dramatic in the March 2003 data set. During the March 2003 event, the peak in suspended-sediment concentration coincided with the peak of the spill, but the peak in streamflow at the Middle Yuba River (11410000) gage did not occur until several hours later. The magnitude of the December 2002 and March 2003 streamflows were similar, which may indicate that the first spill event of the water year flushed most of the finer impounded sediment available for transport over the spillway.

Grain-Size Analysis of Suspended Sediment

Suspended-sediment concentrations and grain sizes of sand-size material measured at the U.S. Geological Survey laboratory in Marina, California, are presented in table 2. Samples processed at the Marina laboratory did not meet the minimum sample mass requirement for pipet analyses of the less-than-0.063-mm sized sediment. However, the less-than-0.063-mm grain-size fraction of replicate samples sent to the USGS sediment laboratory in Menlo Park, California, was analyzed using a laser-diffraction particle-size analyzer. Suspended-sediment concentration, median and mean grain sizes (in µm), and percentages of clay (less than 0.004 mm), silt (0.004 to 0.063 mm), and sand (0.063 mm to 2.0 mm) measured at the Menlo Park laboratory are presented in table 3; full grain-size distributions are presented in Appendix 2.
Table 2 (View this table on a separate page.) Summary of streamflow, suspended-sediment concentrations, and grain sizes of sand-sized suspended sediment at gaging stations in the upper Yuba River watershed, California.
[See figure 1 for station locations. Sand-size material measured by the U.S. Geological Survey in Marina, California. ft3/s, cubic foot per second; mg/L, milligram per liter; mm, millimeter]
Map identifierStation identifierDateTimeStreamflow (ft³/s)Suspended-sediment concentration (mg/L)Grain size percent finer than 2.0 mmGrain size percent finer than 1.0 mmGrain size percent finer than 0.5 mm Grain size percent finer than 0.25 mmGrain size percent finer than 0.125 mmGrain size percent finer than 0.063 mm
MYG1141000011/08/0215:158855 10099989896
  11/09/0208:156696 10098989797
  12/14/0210:001,25079 10099979286
  12/15/0207:3088348 10098969288
  12/16/0211:501,950374 10098959390
  12/16/0211:501,9503751009796959390
  12/16/0211:501,950360 10099979594
  12/17/0213:2517035  100999895
  12/18/0210:009510  100979392
  12/30/0212:001505     194
  03/14/0315:00637     194
  03/15/0315:451,230218 10099989688
  03/16/0315:301006     190
            
SYG1141750011/08/0210:15279116 100100999794
  12/13/0214:2212312 100100767265
  12/14/0208:001,970145 100100908783
  12/15/0214:151,27050 100100969389
  12/16/0214:353,060223 100100898479
  12/17/0209:521,24030 100100938779
  12/17/0210:111,22029   928678
  12/17/0210:111,22031 100100898273
  12/18/0209:4060513   958879
  12/30/0216:0075014   938779
  12/31/0211:311,190199 100100999998
  02/16/0307:0066139 100100959187
  02/16/0307:0066136 100100959388
  02/17/0313:004197     191
  02/17/0313:004198     186
  03/14/0316:0040989   999998
  03/15/0311:302,7904041009797807670
  03/16/0312:3097418   928575
            
YRE1141800003/15/0314:105,40010     189
  03/16/0310:452,9803     195
Table 3 (View this table on a separate page.) Summary of streamflow, suspended-sediment concentrations, and grain sizes of suspended sediment collected at gaging stations in the upper Yuba River watershed, California.
[See figure 1 for station locations. Grain-size material measured at the U.S. Geological Survey in Menlo Park, California. ft3/s, cubic foot per second; mg/L, milligram per liter; mm, millimeter; µm, micrometer]
Map identifierStation identifierDateTimeStreamflow (ft³/s)Suspended sediment concentration (mg/L)Sand (greater than 0.063 mm) (%)Silt (0.004 to 0.063 mm) (%)Clay (less than 0.004 to 0.063 mm) (%) Grain size, median (µm)Grain size, mean (µm)
MYG1141000011/08/0215:2088482306833
  11/09/0208:1766820316932
  12/14/0210:001,25069770231111
  12/15/0207:30889370623865
  12/17/0213:25170392653366
  12/18/0210:0010090584254
  12/30/0212:0015340613955
  02/06/0308:00158131544554
  02/16/0308:00158120584255
  02/17/0314:008350485244
  02/17/0314:0083100653566
  02/17/0314:0083130415933
  03/14/0315:0070120554555
  03/15/0315:451,24022386626109
  03/15/0315:451,2402197652899
  03/16/0315:3010580544654
           
SYG1141750011/08/0210:222791050594155
  12/13/0214:22123180485244
  12/14/0208:001,9701289563568
  12/15/0214:151,270496623277
  12/16/0214:353,060871860221015
  12/18/0209:406059175627911
  12/30/0216:007501110573378
  12/31/0211:301,1902081584155
  02/16/0307:00661367593477
  02/17/0313:0041959583377
  03/14/0316:00409901544544
  03/14/0316:00409830524844
  03/15/0311:302,790411225028915
  03/15/0311:302,790415244927915
  03/16/0312:30974112633576
           
YRE1141800003/15/0314:105,400100544644
  03/16/0310:452,980100564455
Normalized by the mean of the two measurements, the concentrations measured in the Marina laboratory were on average 4.9 percent higher than those measured in the Menlo Park laboratory. Generally higher concentrations measured at the Marina laboratory may reflect the different sample-processing techniques used in the two laboratories (removal of organic material from the full sample and ultrasonicating at Menlo Park). The Marina laboratory measurements of sand content averaged 7.0 percent higher than the measurements at the Menlo Park laboratory. This difference may reflect the removal of organic material, perhaps because the H2O2 reaction not only dissolves free-floating organic material but also the thin organic films on the surfaces of sediment grains. In addition, ultrasound dispersal techniques used at the Menlo Park laboratory may break up particle aggregates thereby reducing grain size relative to the undispersed samples. Concentration and percent sand were measured in the Menlo Park laboratory both before and after removal of organics for a subset of 12 samples from February and March 2003. On average, suspended-sediment concentrations were 28.0 percent higher prior to removal of organic material (reflecting 3–26 mg/L of material removed during the reaction with H2O2) and sand contents were 1.4 percent greater.
Suspended sediment in the upper Yuba River watershed was dominantly silt and clay (typically greater than 85 percent) during water year 2003, and sand concentrations were higher at the South Yuba River (11417500) gage than at the Middle Yuba River (11410000) gage for similar streamflow rates (fig. 10). Small-volume (5 to 10 pints) samples collected for grain-size analyses resulted in high variability among processed replicate samples. These differences underscore the importance of using large-volume samples to obtain more precise grain-size analyses, especially during low-concentration conditions.
Figure 10Relation between percent sand (the proportion of suspended-sediment larger than 0.063 millimeter) and instantaneous streamflow for two gaging stations in the upper Yuba River watershed, California. A, Middle Yuba River (11410000). B, South Yuba River (11417500).
[USGS, U.S. Geological Survey]
Relation between percent sand (the proportion of suspended-sediment larger than 0.063 millimeter) and instantaneous streamflow for two gaging stations in the upper Yuba River watershed, California. A, Middle Yuba River (11410000). B, South Yuba River (11417500).

Suspended-Sediment Rating Curves

Group-average suspended-sediment rating curves for the Middle Yuba River (11410000) and South Yuba River (11417500) gages describe average, summer/fall, first flush, winter, and spring snowmelt conditions (fig. 11). The form and goodness-of-fit of regressions are shown in table 4. Suspended-sediment concentrations generally increase with increasing streamflow indicating an associated increase in stream power (the ability of the river to transport sediment); however, the slopes of the seasonal rating curves differ significantly. Variations in the slopes of the rating curves indicate changes in sediment supply throughout the water year. Under average and below-average precipitation conditions, such as occurred during the study period, sediment supply is greatest during the first flush of the water year; therefore, the first flush curves for the Middle Yuba and South Yuba Rivers have the greatest slopes. Sediment supplies decreased following the first flush; thus, the slopes of the winter rating curves are lower than those of the first flush curves. The spring and summer/fall rating curves had the lowest slopes, indicating lower sediment supplies during spring snowmelt conditions and throughout the dry summer and fall months.
Figure 11ANon-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Average.
See table 4 for regression equation form and summary statistics.
Non-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Average.
Figure 11BNon-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Summer/fall.
See table 4 for regression equation form and summary statistics.
Non-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Summer/fall.
Figure 11CNon-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Fall first flush.
See table 4 for regression equation form and summary statistics.
Non-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Fall first flush.
Figure 11DNon-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Winter.
See table 4 for regression equation form and summary statistics.
Non-linear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Winter.
Figure 11ENonlinear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Spring.
See table 4 for regression equation form and summary statistics.
Nonlinear regression relations between suspended-sediment concentration and instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California. Spring.
Table 4 (View this table on a separate page.) Regression equation form and statistics for gaging stations in the Middle Yuba and South Yuba Rivers in the upper Yuba River watershed, California.
[Note: Regression variables, which include suspended-sediment concentration and streamflow, were converted to base-10 logarithms. r2, coefficient of determination. a is the Y intercept and b is the regression coefficient in equation 1. N, number of data points: Data points were used to determine group-averaged dataset; group-averaged data points were used in the regression analysis]
 abr2Standard errorP valueF statisticCritical F statistic6N7N (group-averaged)
Middle Yuba River (MYG, Station ID 11410000)
Average1−1.7761.2780.950.1650.0003261.467519
Summer/fall2−0.6020.5160.280.1250.05051.513514
First flush3−4.3772.9870.600.4230.001181.515414
Winter4−1.8381.3170.910.2070.0001781.437119
Spring snowmelt5−0.7360.6020.650.1450.008131.61749
          
South Yuba River (SYG, Station ID 11417500)
Average1−2.0661.2210.870.3100.0001201.469820
Summer/fall2−1.5481.0240.570.2090.002161.512714
First flush3−3.1271.9450.790.3830.000401.514512
Winter4−2.7501.4600.910.2730.0001841.438020
Spring snowmelt5−0.7980.5380.670.1860.007201.61659
The accuracy of seasonal suspended-sediment rating curves was assessed based on 95-percent confidence intervals for predicted values (fig.11A–E) and summary statistics (table 4). Confidence intervals denote a range around the predicted value where the "true" value can be expected with a given level of certainty, which is 95 percent in this case, and the confidence interval width indicates uncertainty. The first flush regressions display the widest confidence intervals, and therefore the predicted suspended-sediment concentrations have the greatest associated uncertainty. The confidence intervals for the summer/fall and spring snowmelt rating curves are greater than those for the winter and average curves indicating greater accuracy for the winter and average curves.
The following is a synopsis of the summary statistics presented in table 4. The p value represents the probability of error associated in accepting the predicted results as true. Higher p values indicate less confidence in the regression as a reliable indicator of the relation between suspended-sediment concentration and streamflow. Typically, p values less than or equal to 0.05 are considered borderline statistically significant, p values less than or equal to 0.01 commonly are considered statistically significant, and p values less than or equal to 0.001 often are considered highly significant. The total variation in predicted suspended-sediment concentrations accounted for by the regression equations is given by r2, which can also be used as a measure of the strength of the regression relation. The standard error is an overall indication of the accuracy with which the regression predicts the dependence of suspended-sediment concentration on streamflow; however, the magnitude of the standard error is proportional to the magnitude of the dependent variable. Thus this statistic cannot be used to compare the accuracies of several of the regressions. The p values of all the regressions listed in table 4 were 0.05 or less, indicating statistical significance. In addition, the F statistic was greater than the critical F (alpha = 5 percent) for all regressions in table 4, providing further evidence of statistical significance. The r2 values for the first flush and spring snowmelt regressions for the Middle Yuba and South Yuba Rivers generally were lower than those for the average and winter regressions; the r2 values for the summer/fall regressions were extremely low. Consequently, the average and winter regressions have a greater likelihood for predicting suspended-sediment concentrations closest to the true value.

Bed Load

Bed-Load Rating Curves

Bed-load rating curves (fig. 12) indicate that the Middle Yuba River has greater transport capacity (the ability to transport bed load) than the South Yuba River for a given instantaneous streamflow, even though bed material at the Middle Yuba River (11410000) gage site (fig. 7) is coarser because of deposition of fine-grained bed material in upstream reservoirs. The greater transport capacity at the Middle Yuba River (11410000) gage, compared with that at the South Yuba River (11410000) gage, can be attributed to a narrower and deeper channel that results in higher streamflow velocities (fig. 8) and to a smaller component of form drag that affects bed-shear stresses. The high slopes of the velocity-streamflow relations (fig. 8) further demonstrate that the Middle Yuba and South Yuba Rivers experience a rapid increase in capacity and competence (the size of the largest particle a stream can entrain under any given set of hydraulic conditions) with increasing streamflow.
Figure 12Relation of bed-load transport to instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California.
Bed-load rating curves were developed using an empirical transport model for mixed-size sediment (Wilcock and Crowe, 2003). Note that the bed-load transport was developed only for the range of flows observed during the study period from 2001 to 2003.
Relation of bed-load transport to instantaneous streamflow for the Middle Yuba River (11410000) and South Yuba River (11417500) gaging stations in the upper Yuba River watershed, California.

Shady Creek Bed-Load Measurements

The accuracy of predicted bed-load rating curves was assessed using bed-load measurements collected in Shady Creek, a tributary to the South Yuba River that has been severely impacted by hydraulic mining (fig. 13). Shady Creek bed-load rating curves, a comparison of bed-load measurements and predicted bed-load transport rates, and grain-size distributions of bed-load samples are presented in figure 14, table 5, and figure 15 respectively.
Figure 13Extensive volumes of historical hydraulic-mining sediment are located in Shady Creek, a tributary to the South Yuba River in the upper Yuba River watershed, California.
View is looking upstream along the left bank.
Extensive volumes of historical hydraulic-mining sediment are located in Shady Creek, a tributary to the South Yuba River in the upper Yuba River watershed, California.
Figure 14Relation of bed-load transport and instantaneous streamflow, and bed-load measurements for bed-load sampling sites on Shady Creek, a tributary to the South Yuba River in the upper Yuba River watershed, California.
See figure 6 for site locations.
Relation of bed-load transport and instantaneous streamflow, and bed-load measurements for bed-load sampling sites on Shady Creek, a tributary to the South Yuba River in the upper Yuba River watershed, California.
Table 5 (View this table on a separate page.) Measured bed load and predicted bed-load transport rates for two sites along Shady Creek in the upper Yuba River watershed, California.
[See figure 6 for location of sampling sites. ft3/s, cubic feet per second; tons/day, tons per day]
      Predicted bed-load transport rates (tons/day) 
Sampling locationSample numberDateTimeStreamflow (ft³/s)Measured bed-load transport (tons/day)Rust Pit rating curveShady Road rating curveRatio (predicted/measured)¹
Rust PitRP-1a02/17/0209:00100.70.2 29
 RP-1b02/17/0209:10130.80.5 63
 RP-2a04/28/0311:202214.32.3 16
 RP-2b04/28/0311:302816.84.6 27
Above Old Hwy 49 BridgeH49-1a02/25/0411:15191289.9 817.3282
 H49-1b02/25/0411:50196480.5 817.3170
 H49-2a02/25/0414:40201487.9 980.2201
 H49-2b02/25/0415:09207267.7 980.2366
 H49-3a02/26/0415:406694.2 134.4143
 H49-3b02/26/0416:1672214.4 134.463
 H49-4a02/26/0410:0177126.3 224.5178
 H49-4b02/26/0410:198089.2 224.5252
Figure 15Cumulative grain-size distributions for bed-load samples collected on Shady Creek, a tributary to the South Yuba River in the upper Yuba River watershed, California.
The fraction of the bed-load sample from Rust Pit consisting of grains less than 1.4 millimeter was not sieved. Paired samples are indicated by matching colors. The order of collection of the pairs is indicated by “a” and “b” labels. See figure 6 for site locations and table 5 for information about paired samples.
Cumulative grain-size distributions for bed-load samples collected on Shady Creek, a tributary to the South Yuba River in the upper Yuba River watershed, California.
Shady Creek bed-load rating curves were developed for two locations (Rust Pit and Shady Road, fig. 6). Subsequent to developing the rating curves, sites were chosen for bed-load measurements. Low streamflow conditions were measured at the Rust Pit wading site and higher streamflow conditions were measured at the Old Hwy 49 Bridge site (fig. 6). Predicted bed-load transport at the Shady Road site was inferred to be representative of bed-load transport at the Old Hwy 49 Bridge site; therefore, the Shady Road rating curve was used to estimate bed-load transport at the Old Hwy 49 Bridge site. Use of the Shady Road rating curve to estimate bed-load transport at the Old Hwy 49 Bridge site was justified based on the equation of continuity and the character of the channel between the two sites. Downstream of the Shady Road site, the channel transitions into a narrower, steeper, bedrock channel with negligible channel storage; therefore following the laws of conservation, bed-load transported past the Shady Road site subsequently passes the Old Hwy 49 Bridge.
Overall, the bed-load measurements agreed well with predicted curves; bed-load measurements were generally within the bounds of the bed-load rating curves (fig. 14). Grain-size distributions for paired bed-load samples agreed well; sediment values were generally within 10 percent of each other (fig. 15). However, transport rates at the Old Hwy 49 site were generally overpredicted and transport rates were generally underpredicted for the Rust Pit site (table 5).

Sediment Transport

There are three ways of defining total sediment discharge, the sum of all sediment passing a gaging station per unit time. (1) Total sediment discharge may be divided into fine-grained material and bed-material fractions. Fine-material discharge consists of particles finer than those normally found in the streambed. Bed-material discharge is composed of particles typically found in considerable quantity in the streambed. (2) Total sediment discharge may be divided into suspended-sediment, whose weight is entirely supported by the surrounding fluid, and into bed load, whose weight is supported primarily by the streambed. (3) Total sediment discharge may also be divided into sampled and unsampled sediment discharge. Owing to physical limitations of depth-integrating suspended-sediment samplers, samples are only collected from the water surface to within 0.3 ft of the streambed. Sampled sediment discharge consists of both fine material and bed material transported in suspension greater than 0.3 ft above the streambed. Unsampled sediment discharge (unsampled by the bed-load sampler) consists of both fine material and bed material transported in suspension less than 0.3 ft above the streambed and bed material transported as bed load. In this report, total sediment discharge equates to the sum of sampled suspended-sediment discharge and estimated bed-load discharge.

Annual Sediment Discharge

Annual sediment discharge was calculated at the Middle Yuba River (11410000) gage and South Yuba River (11417500) gage for water years 2001, 2002 and 2003 (table 6). Suspended-sediment discharge was calculated using seasonal suspended-sediment rating curves and mean daily streamflow, whereas bed-load discharge was calculated using the flow-duration sediment transport method (Glysson, 1987), which employed bed-load rating curves and 15-minute streamflow data.
Table 6 (View this table on a separate page.) Annual sediment discharge and bed-load estimates for gaging stations on the Middle Yuba and South Yuba Rivers in the upper Yuba River watershed, California.
[Annual suspended-sediment discharge estimated using seasonal suspended-sediment rating curves. Annual bed-load discharge estimated using mixed-sediment model (Wilcock and Crowe, 2003). Total annual sediment discharge equals annual suspended-sediment discharge plus annual bed-load discharge. tons/mi2, tons per square mile; mi2, square mile]
YearAnnual suspended-sediment discharge (tons)Annual bed-load discharge (tons)Total annual sediment discharge (tons)Annual sediment yield (tons/mi²)
South Yuba River (SYG, Station ID 11417500 [drainage area 308 mi²])
200173017312
20024,700164,71615
20037,600897,68925
Average annual sediment discharge  4,37914
     
Middle Yuba River (MYG, Station ID 11410000 [drainage area 198 mi²])
200115001501
200291039135
20032,000192,01910
Average annual sediment discharge  1,0275
Estimated annual sediment discharges at the Middle Yuba River (11410000) gage were significantly lower than those at the South Yuba River (11417500) gage even when compared by drainage area. The main contributing factor to the difference in sediment loads is that 88 percent of the Middle Yuba River watershed lies upstream of Log Cabin and Our House Reservoirs. This effect is compounded by significant flow diversions above the Middle Yuba River (11410000) gage, which resulted in a median daily flow for the project period of 57 ft3/s at the Middle Yuba River (11410000) gage compared with 98 ft3/s at the South Yuba River (11417500) gage. Because the South Yuba River has higher flows and no man-made restrictions to sediment movement in the lower basin, it is able to transport a greater and coarser sediment load.
In water years 2001, 2002, and 2003, the Middle Yuba River transported only 9, 14, and 31 percent, respectively, of the load transported by the South Yuba River at the gaging stations. The increase of sediment discharge in water year 2003 at the Middle Yuba River (11410000) gage, relative to that at the South Yuba River (11417500) gage, may reflect the influence of spill events at Log Cabin and Our House Dam reservoirs. Our House Reservoir, the larger of the two facilities, spilled only 1 day in 2001, 11 days in 2002, and 21 days in 2003. Because anomalously high suspended-sediment concentrations (fig. 9B inset) can occur during spill events, annual suspended-sediment discharge may be elevated during years in which these reservoirs spill. Storm sampling in December 2002 and March 2003 indicates that the first spill event in December 2002 flushed a fraction of suspendable-sized reservoir sediment impounded within Log Cabin and Our House Dam reservoirs. As the volume of suspendable-sized reservoir sediment was depleted, subsequent spills, such as occurred in March 2003, contributed smaller amounts of sediment.
The percentage of annual sediment discharge transported as bed load was less than 1 percent throughout the study period, which was quite low and unexpected given the abundance of bed material available for transport. Significant volumes of hydraulic-mining sediment remain stored in smaller upland tributary channels. The mining sediment tends to be finer grained and therefore more transportable than bed material derived from non-mining sources (James, 2005). Consequently, stored sediment from hydraulic mining represents a significant sediment source in the Middle Yuba and the South Yuba Rivers (Curtis and others, 2005).
It is important to note that 88 percent of the Middle Yuba River watershed lies upstream of Log Cabin and Our House Reservoirs; therefore most of the source area for coarser sediment in the Middle Yuba River was cutoff by the reservoirs, which subsequently resulted in decreased bed-load transport and coarsening of the channel bed at the Middle Yuba River (11410000) gage (fig. 7). However, the low bed-load transport rates at the South Yuba River (11417500) gage remain an anomaly (table 6). Below-average to average precipitation conditions occurred throughout the project period, which likely influenced the low percentage of annual sediment discharge transported as bed load. During above-average water years, the percentage of bed load may change as greater streamflows mobilize larger volumes of bed material.
A better representation of the long-term average bed-load transport can be made using estimates of bed load transported by the Feather River. The Feather River is adjacent to the Yuba River and has a similar land-use history including hydraulic mining and timber harvesting. On the basis of deposition in Lake Oroville, long-term average sediment discharge for the Feather River from 1902 to 1962 consisted of approximately 13 percent bed load (Porterfield and others, 1978).
Annual suspended-sediment discharges reported here are compared with those published in the USGS annual data reports (table 7). Annual suspended-sediment discharges published in USGS annual data reports were estimated using a software package called Graphical Constituent Loading Analysis System (GCLAS; http://oh.water.usgs.gov/gclas/). GCLAS is designed to compute mean daily suspended-sediment concentrations and mean daily sediment loads. Using suspended-sediment concentrations and mean daily streamflow, GCLAS implements a user-defined interpolation between suspended-sediment concentration data points to predict a continuous trace of mean daily suspended-sediment concentrations. A typical time series of concentration data includes one concentration data point every 1 to 3 days. Load computations are made by applying a mid-interval method to the concentration time series data, which involves interpolating concentrations during periods between data points. Options for interpolation are user-defined and include linear (preferred) or log-linear equations.
Table 7 (View this table on a separate page.) Annual suspended-sediment discharge for gaging stations on the Middle Yuba (MYG) and South Yuba (SYG) Rivers in the upper Yuba River watershed, California.
[GCLAS, Graphical Constituent Loading Analysis System, used for U.S. Geological Survey annual data reports (Rockwell and others, 2001; Smithson and others, 2002; Friebel and others, 2003). Percent difference is the difference between the GCLAS and rating curve estimates divided by the GCLAS estimate. Rating curve regression equations listed in table 4 for sample periods]
Water yearSampling periodAnnual suspended-sediment dischargePercent difference
  Estimated using GCLAS (tons)Estimated using rating curves (tons) 
South Yuba River  (SYG, Station ID 11417500)
200111/08/00–09/30/011,50069054
200210/01/01-06/30/023,4004,700-38
200311/01/02-05/31/027,7007,5003
Middle Yuba River (MYG, Station ID 11410000)
200111/08/00–09/30/011401400
200210/01/01-06/30/02480890-85
200311/01/02-05/31/022,4001,90021
The two methods for estimating annual suspended-sediment discharge produced substantially different results (table 7). The difference in annual suspended-sediment discharge estimated using the seasonal rating curves and that estimated using GCLAS ranged from –85 to +21 percent for the Middle Yuba River and from –38 to +54 percent for the South Yuba River. The percent difference was generally greatest for water years that had below average precipitation (WY2001 and 2002); however, there was 0 percent difference for the Middle Yuba River in WY2001. Wetter conditions prevailed during WY2003, and the number of samples increased. The time series dataset for suspended-sediment concentrations in WY2003 included four storm sampling events. The increased number of samples collected during WY2003 likely improved the GCLAS estimates of sediment loads.

Event-Based Suspended-Sediment Discharge

A continuous time series of calibrated OBS data and seasonal suspended-sediment rating curves were used to evaluate event-based suspended-sediment transport. Calibration of the optical backscatter data required a relatively stable particle-size distribution. Over the range of flows represented in the calibration data sets (50 to 2,000 ft3/s), the fraction of fine-grained sediment (percent less than 0.063 mm) remained quite high, varying from 73 to 99 percent, which indicates that fine-grained sediment dominates the suspended load. A plot of the ratio of suspended-sediment concentration to sensor output voltage as a function of suspended particles finer than 0.063 mm (fig. 16) has an essentially constant slope, illustrating the minimal effects of particle size on sensor calibration (fig. 17). At higher flows, as more sand goes into suspension, the effects of particle size likely increase; therefore, sensor calibrations indicate an increase in uncertainty with increasing streamflow, indicated by the large deviation outside the prediction interval by the confidence bounds at higher suspended-sediment concentrations (fig. 17).
Figure 16Ratio of suspended-sediment concentration to optical backscatter sensor output voltage as a function of suspended particles finer than 0.063 millimeter for two gaging stations: Middle Yuba River (11410000) and South Yuba River (11417500).
OBS, optical backscatter sensor; SSC, suspended-sediment concentration.
Ratio of suspended-sediment concentration to optical backscatter sensor output voltage as a function of suspended particles finer than 0.063 millimeter for two gaging stations: Middle Yuba River (11410000) and South Yuba River (11417500).
Figure 17Relation of suspended-sediment concentration and optical backscatter sensor (OBS) output for two gaging stations in the upper Yuba River watershed, California. A, Middle Yuba River (11410000); B, South Yuba River (11417500).
Relation of suspended-sediment concentration and optical backscatter sensor (OBS) output for two gaging stations in the upper Yuba River watershed, California. A, Middle Yuba River (11410000); B, South Yuba River (11417500).
The accuracy of the calibrated OBS data was assessed using nonparametric prediction intervals and 95-percent confidence intervals. The nonparametric prediction interval (Helsel and Hirsch, 1992, p. 76) contains one standard deviation (68.26 percent) of the calibration dataset and represents essentially the same error prediction limits as the root mean square (RMS) error of prediction in ordinary least–squared regression, and the confidence intervals represent a range of predicted values where the true value can be expected to fall with 95 percent certainty. The smaller width of the prediction and confidence intervals for the Middle Yuba River calibration equation indicates greater accuracy than that for the South Yuba River calibration equation. In addition, confidence bounds increase with increasing concentration and sensor output voltage, indicating greater accuracy at low to moderate concentrations.
Calibrated OBS data and winter suspended-sediment rating curves were used to evaluate suspended-sediment transport for two moderate discharge events occurring during December 2002 at the Middle Yuba River (11410000) and South Yuba River (11417500) gages (table 8). Figure 18 shows streamflow and predicted suspended-sediment concentrations based on calibrated OBS output and winter rating curves. During the December 20−23, 2002 storm, the OBS registered delayed sediment peaks at both the Middle Yuba River (11410000) and South Yuba River (11417500) gages. The OBS sediment peaks occurred 5 hours after the streamflow peak at the Middle Yuba River (11410000) gage (fig. 18A) and almost 24 hours after the streamflow peak at the South Yuba River (11417500) gage (fig. 18B). Suspended-sediment transport estimated using the winter rating curve during the December 20−23, 2002, storm was 86 percent of that estimated using the calibrated OBS data at the Middle Yuba River (11410000) gage and only 50 percent of that estimated using the OBS data at the South Yuba River (11417500) gage (table 8). During the December 27−30, 2002 storm, the OBS registered early sediment peaks at both the Middle Yuba River (11410000) and South Yuba River (11417500) gages. The OBS sediment peaks occurred 2 hours before the streamflow peak at the Middle Yuba River (11410000) gage (fig. 18C) and 5 hours before the streamflow peak at the South Yuba River (11417500) gage (fig. 18D). Suspended-sediment transport during the December 27−30, 2002, storm, estimated using the winter rating curve, was nearly five times higher than that estimated using the OBS data for the Middle Yuba River (11417500) gage, whereas the two methods gave estimates within 13 percent for the South Yuba River (11410000) gage (table 8).
Figure 18ABInstantaneous streamflow and suspended-sediment concentrations (SSC) during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California, December 20 to 23, 2002.
[OBS, optical backscatter system]
Instantaneous streamflow and suspended-sediment concentrations (SSC) during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California, December 20 to 23, 2002.
Figure 18CDInstantaneous streamflow and suspended-sediment concentrations during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California, December 27 to 30, 2002.
Instantaneous streamflow and suspended-sediment concentrations during storm events at the Middle Yuba River (11410000) and South Yuba River (11417500) in the upper Yuba River watershed, California, December 27 to 30, 2002.
The percent difference ranged from 50 to −369 percent and an average of the four percent-difference values in table 8 is −79 percent. OBS is preferred over rating curves when event-based suspended-sediment transport is assessed because the OBS data provide an independent, continuous time-series dataset with detailed information about the timing of sediment peaks and the duration of sediment loads, whereas the rating curve is dependent on the streamflow dataset. As a result, rating curves may misrepresent sediment transport in situations where the sediment transport does not mimic streamflow. In these situations, calibrated OBS data can provide a more accurate estimate of suspended-sediment transport.
Compared to the OBS data, the rating curves underestimated suspended-sediment discharge during the December 20−23, 2002, storm characterized by lower streamflows and overestimated suspended-sediment discharge during the December 27−30, 2002, storm characterized by higher streamflows (table 8). This could indicate that the slope of the winter rating curves is too steep such that suspended-sediment concentrations are underpredicted at lower streamflows and overpredicted at higher streamflows (table 8). Alternatively, this may indicate a depletion of suspended sediment resulting in lower concentrations during the December 27−30, 2002, storm that were measured using the OBS but could have been misrepresented by the rating curves, which rely on the streamflow dataset.
Table 8 (View this table on a separate page.) Event-based suspended-sediment discharge at gaging stations on the Middle Yuba and South Yuba Rivers in the upper Yuba River watershed, California.
[Percent difference is the difference between the OBS (optical backscatter sensor) and rating curve estimates divided by the OBS estimate. ft3/s, cubic feet per second]
Storm events Event-based suspended-sediment discharge
 Peak streamflow (ft3/s)Estimated using OBS data1(tons) Estimated using rating curves2(tons) Percent difference
Middle Yuba River (MYG, USGS Station ID 11410000)
December 20–23, 2002346211814
December 27–30, 200299564300–369
     
South Yuba River (SYG, USGS Station ID 11417500)
December 20–23, 200298420010050
December 27–30, 20021980520590–13

Summary

The purpose of this study was to characterize annual and event-based sediment transport in the upper Yuba River watershed during water years 2001, 2002, and 2003. Data collection included gaging streamflow and sampling suspended-sediment concentration at four upper Yuba River gaging stations: Middle Yuba River (11410000), South Yuba River (11417500), Yuba River below New Colgate Powerplant (11413700), and Yuba River below Englebright Dam (11418000). Suspended-sediment samples were collected 1 to 7 days per week at all gaging stations, depending on hydrologic conditions, and samples were collected at the Middle Yuba River (11410000) gage and South Yuba River (11417500) gage during four storms in water year 2003. Additional suspended-sediment samples were collected at the Middle Yuba River (11410000), South Yuba River (11417500), and Yuba River below Englebright Dam (11418000) gages for detailed grain-size analyses. Continuously recording optical backscatter sensors (OBS) were installed at the Middle Yuba River (11410000) gage and South Yuba River (11417500) gage to provide 15-minute time-series records of suspended-sediment concentration. Bed-load rating curves were developed for the Middle Yuba River (11410000) and South Yuba River (11417500) gage sites, and two sites on Shady Creek (Rust Pit and Shady Road) were estimated using an empirical bed-load transport relation (the Hopkins model); the accuracy of bed-load rating curves was assessed using bed-load measurements from Shady Creek, which agreed well with predicted curves. Finally, methods for estimating annual and event-based suspended-sediment discharge were compared.
Group-average suspended-sediment rating curves for the Middle Yuba River (11410000) and South Yuba River (11417500) gages describe average, summer/fall, first flush, winter, and spring snowmelt conditions. Variations in the slopes of the rating curves indicate changes in sediment supply throughout the water year. Under below-average and average precipitation conditions, such as occurred during the study period, sediment supply is greatest during the first flush of the water year; the rating curves for the first flush have the greatest slopes. Sediment supplies decreased following the first flush; thus, the slopes of the winter rating curves are lower than those of the first flush curves. The spring and summer/fall rating curves had the lowest slopes, indicating low supply conditions.
Although summary statistics and confidence bounds indicate that the accuracy of individual rating curves varies considerably, p values (less than 0.05) and F statistics (greater than the critical F for alpha = 5 percent) indicate statistical significance for all the seasonal suspended-sediment regressions. The r2 values for the first flush and spring snowmelt regressions generally were lower than those for the average and winter regressions; the r2 values for the summer/fall regressions were extremely low. The first flush regressions display the widest confidence intervals, and therefore the predicted suspended-sediment concentrations have the greatest associated uncertainty. The confidence intervals for the summer/fall and spring snowmelt rating curves are greater than those for the winter and average curves indicating greater accuracy for the winter and average curves. Thus, the winter and average regressions have the greatest likelihood for predicting suspended-sediment concentrations closest to the true value.
Seasonal suspended-sediment rating curves were developed to aid in the calibration of a watershed-scale sediment transport model and to assess the magnitude and duration of sediment loads that may impact the viability of long-term fish-introduction strategies. The seasonal rating curves were used to estimate annual suspended-sediment loads during water years 2001, 2002, and 2003. These estimates were compared with previously published annual suspended-sediment loads estimated using an interpolation software package (GCLAS). The percent difference ranged from −85 to +54 percent and averaged −7.5 percent.
Event-based suspended-sediment loads were estimated using calibrated OBS data and seasonal rating curves for two storms during December 2002. The percent difference ranged from 50 to −369 percent and averaged −79 percent. Compared to the OBS data, the rating curves underestimated suspended-sediment transport during the December 20−23, 2002, storm characterized by lower streamflows and overestimated suspended-sediment transport during the December 27−30, 2002, storm characterized by higher streamflows. This may indicate that the slopes of the winter rating curves are too steep such that suspended-sediment concentrations are underpredicted at lower streamflows and overpredicted at higher streamflows. Alternatively, this may indicate a depletion of suspended-sediment resulting in lower concentrations during the December 27−30, 2002, storm that were measured using the OBS and misrepresented by the rating curves, which rely on the streamflow dataset. The OBS data provided an independent continuous time-series dataset containing detailed information about the timing of sediment peaks and the duration of sediment loads; therefore the calibrated OBS estimates of suspended sediment transport is preferred over the rating curve estimates.
For 2001–2003, the estimated average annual sediment yield at the Middle Yuba River (11410000) gage (5 tons/mi2) was significantly lower than that for the South Yuba River (11417500) gage (14 tons/mi2); in both rivers, bed load represented less than 1 percent of the total annual load throughout the project period. Suspended sediment at both the Middle Yuba River (11410000) and South Yuba River (11417500) gages was typically greater than 85 percent silt and clay during water year 2003, and sand concentrations at the South Yuba River (11417500) gage were typically higher than those at the Middle Yuba River (11410000) gage for a given streamflow. Factors contributing to differences in sediment loads and grain-size distributions on the Middle Yuba and South Yuba Rivers include drainage area, flow diversions, and deposition of bed-material-sized sediment in Middle Yuba River reservoirs. Owing to its larger drainage area, higher flows, and absence of man-made structures that restrict sediment movement in the lower basin, the South Yuba River transports a greater and coarser sediment load.
Rainfall-runoff conditions were below average during the first two years of this study and average during the last year. Because sediment transport is heavily influenced by extreme rainfall-runoff events, the results of this study are somewhat limited. Additional data collected during wetter years and at higher streamflows would greatly improve the value of the rating curves as tools to estimate long term transport.

Appendix 1.

Table A1a (View this table on a separate page.) Suspended-sediment concentration samples and associated instantaneous streamflow for the Middle Yuba River near North San Juan (MYG) collected during water years 2001, 2002, and 2003.
[USGS Marina sediment laboratory uses 0.5 mg/L (milligram per liter) as the detection limit for reporting suspended-sediment concentration (SSC); therefore, samples with SSC of less than 0.5 mg/L are reported as 0.25 mg/L (Helsel and Hirsch, 1992). ft3/s, cubic feet per second]
Map identifierStation identifierDateTimeInstantaneous streamflow (ft³/s)Suspended-sediment concentration (mg/L)
MYG1141000011/07/001020490.25
 1141000011/08/001115490.25
 1141000011/13/001010510.25
 1141000011/14/000955532
 1141000011/15/00 0935521
 1141000011/16/00 0940510.25
 1141000011/17/001330491
 1141000011/20/001205491
 1141000011/21/001150491
 1141000011/22/001030491
 1141000011/24/001100491
 1141000011/27/001100492
 1141000011/29/001130682
 1141000011/29/001130682
 1141000011/30/001100532
 1141000012/01/001125511
 1141000012/04/001100493
 1141000012/05/001120491
 1141000012/06/001115492
 1141000012/07/001100482
 1141000012/11/001100513
 1141000012/12/001100662
 1141000012/13/001115533
 1141000012/14/0011008630
 1141000012/15/0010458615
 1141000012/18/001100566
 1141000012/19/001050551
 1141000012/20/001045534
 1141000012/21/001045531
 1141000012/22/001050556
 1141000012/26/001100515
 1141000012/27/001055512
 1141000012/27/001055511
 1141000012/28/001030511
 1141000012/29/001045511
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 1141000003/15/0311301110224
 1141000003/15/0313301330158
 1141000003/15/0313301330157
 1141000003/15/0315301260133
 1141000003/15/0315301260109
 1141000003/16/03073023610
 1141000003/16/03073023610
 1141000003/16/0309301839
 1141000003/16/0309301838
 1141000003/16/0311301456
 1141000003/16/0311301457
 1141000003/16/03133012015
 1141000003/16/0313301205
 1141000003/16/0315301055
 1141000003/16/0315301055
 1141000003/17/031015885
 1141000003/17/031015884
 1141000003/19/031100700.25
 1141000003/19/031100701
 1141000003/21/031100702
 1141000003/21/031100701
 1141000003/24/031110702
 1141000003/24/031110701
 1141000003/26/031105843
 1141000003/26/031105842
 1141000003/28/031110722
 1141000003/28/031110722
 1141000003/31/030915654
 1141000003/31/030915654
 1141000004/03/031030632
 1141000004/03/031030631
 1141000004/04/031400741
 1141000004/04/031400741
 1141000004/09/031045603
 1141000004/09/031045602
 1141000004/11/031120601
 1141000004/11/031120602
 1141000004/14/0310401908
 1141000004/14/0310401908
 1141000004/16/0311001183
 1141000004/16/0311001182
 1141000004/18/0310251104
 1141000004/18/0310251102
 1141000004/21/0310551055
 1141000004/21/0310551050.25
 1141000004/23/031040903
 1141000004/23/031040902
 1141000004/28/03105020056
 1141000004/28/03105020054
 1141000004/30/0310351553
 1141000004/30/0310351553
 1141000005/02/0310101271
 1141000005/020310101274
 1141000005/05/0310505115
 1141000005/05/0310505116
 1141000005/06/0310103264
 1141000005/06/0310103264
 1141000005/07/0310501473
 1141000005/07/0310501476
 1141000005/08/0310351806
 1141000005/08/0310351804
 1141000005/09/0310051733
 1141000005/09/0310051734
 1141000005/14/0311051201
 1141000005/14/0311051202
 1141000005/16/0310101551
 1141000005/16/0310101554
 1141000005/19/0310551001
 1141000005/19/0310551002
 1141000005/21/031110971
 1141000005/21/031110972
 1141000005/22/031040971
 1141000005/22/031040972
 1141000005/23/031115954
 1141000005/23/031115951
 1141000005/27/031030881
 1141000005/27/031030881
 1141000005/29/0310252596
 1141000005/29/0310252598
Table A1b (View this table on a separate page.) Suspended-sediment concentration samples and associated instantaneous streamflow for the South Yuba River at Jones Bar near Grass Valley (SYG) collected during water years 2001, 2002, and 2003.
[USGS Marina sediment laboratory uses 0.5 mg/L (milligram per liter) as the detection limit for reporting suspended-sediment concentration (SSC); therefore, samples with SSC of less than 0.5 mg/L are reported as 0.25 mg/L (Helsel and Hirsch, 1992). ft3/s, cubic feet per second]
Map identifierStation identifierDateTimeInstantaneous streamflow (ft³/s)Suspended-sediment concentration (mg/L)
SYG1141750011/07/001235660.25
 1141750011/08/001220650.25
 1141750011/09/001205631
 1141750011/13/001145591
 1141750011/14/001115670.25
 1141750011/15/001050700.25
 1141750011/16/001055630.25
 1141750011/17/001445620.25
 1141750011/20/001015610.25
 1141750011/21/001015610.25
 1141750011/22/000910611
 1141750011/24/000910611
 1141750011/27/000930612
 1141750011/28/001000610.25
 1141750011/29/001000732
 1141750011/30/0009451449
 1141750012/04/000940671
 1141750012/05/001000650.25
 1141750012/06/001045631
 1141750012/06/001045632
 1141750012/07/001040631
 1141750012/07/001310652
 1141750012/08/000930631
 1141750012/09/000945631
 1141750012/12/0009351192
 1141750012/13/0009451025
 1141750012/13/0009451024
 1141750012/14/0009301587
 1141750012/15/00092026228
 1141750012/18/0009451072
 1141750012/19/000930952
 1141750012/20/000920892
 1141750012/20/000920892
 1141750012/21/000920844
 1141750012/22/000930891
 1141750012/26/000930740.25
 1141750012/27/000930733
 1141750012/27/000930732
 1141750012/28/000910714
 1141750012/29/000920700.25
 1141750001/02/010920671
 1141750001/03/010925663
 1141750001/03/010925661
 1141750001/04/010920630.25
 1141750001/05/011130654
 1141750001/09/010930751
 1141750001/10/010940811
 1141750001/10/010940811
 1141750001/11/01104531034
 1141750001/11/01120130730
 1141750001/12/01094517819
 1141750001/16/010915921
 1141750001/17/010930831
 1141750001/17/010930831
 1141750001/18/010930791
 1141750001/19/010930800.25
 1141750001/22/011320771
 1141750001/23/010935772
 1141750001/24/01094016310
 1141750001/24/01094016310
 1141750001/25/01094014112
 1141750001/26/0109301586
 1141750001/29/01094011411
 1141750001/30/0109201224
 1141750001/31/0109351038
 1141750001/31/0109351038
 1141750002/01/01093599.52
 1141750002/02/010925921
 1141750002/03/010935976
 1141750002/05/0109401243
 1141750002/06/0112101253
 1141750002/07/0109251212
 1141750002/07/0109251217
 1141750002/08/0109251032
 1141750002/09/010920962
 1141750002/10/01103016918
 1141750002/11/0109502056
 1141750002/12/0109201804
 1141750002/13/0109301622
 1141750002/15/0109201271
 1141750002/15/0109201272
 1141750002/16/0109251273
 1141750002/20/01094044576
 1141750002/22/01092573184
 1141750002/23/01093047826
 1141750002/26/0109403356
 1141750002/27/0109302854
 1141750002/27/01103028217
 1141750002/27/0114352773
 1141750002/28/0109352503
 1141750003/01/0109252233
 1141750003/05/0109401290168
 1141750003/06/01100067617
 1141750003/07/01101551410
 1141750003/08/0110054785
 1141750003/09/0109454235
 1141750003/09/0109454235
 1141750003/12/0109452753
 1141750003/13/0109452592
 1141750003/14/0110002592
 1141750003/14/0110002592
 1141750003/15/0109502551
 1141750003/16/0109502411
 1141750003/20/0109453122
 1141750003/21/0109403353
 1141750003/21/0109403353
 1141750003/22/0109203186
 1141750003/23/0111003075
 1141750003/27/0112253372
 1141750003/28/0109503072
 1141750003/29/0109453181
 1141750003/30/0109502923
 1141750003/30/0109552921
 1141750004/02/0109402541
 1141750004/03/0109452301
 1141750004/04/0109452111
 1141750004/04/0109502111
 1141750004/05/0109551901
 1141750004/06/0109451821
 1141750004/09/0109501982
 1141750004/10/0109451911
 1141750004/11/0109551872
 1141750004/12/01091525210
 1141750004/13/0109352053
 1141750004/16/0109301961
 1141750004/17/0109502051
 1141750004/18/0110002141
 1141750004/19/0109452500.25
 1141750004/20/0110003428
 1141750004/23/0109503012
 1141750004/24/0109553052
 1141750004/24/0109553052
 1141750004/25/0109453012
 1141750004/26/0109503143
 1141750004/26/0109503142
 1141750004/30/0109402393
 1141750005/01/0109452495
 1141750005/02/0109452433
 1141750005/03/0109452123
 1141750005/04/0109401984
 1141750005/07/0109551892
 1141750005/08/0109501874
 1141750005/09/0109351894
 1141750005/10/0109301774
 1141750005/11/0109301682
 1141750005/14/0109301451
 1141750005/15/0110001401
 1141750005/16/0109501502
 1141750005/17/0109451391
 1141750005/18/0109301281
 1141750005/21/0109301022
 1141750005/22/010925923
 1141750005/23/010945923
 1141750005/24/010945851
 1141750004/05/010935823
 1141750004/09/010945713
 1141750005/30/010940693
 1141750005/31/010950642
 1141750006/01/010940624
 1141750006/04/010930642
 1141750006/05/010935592
 1141750006/06/010945582
 1141750006/07/010940591
 1141750006/08/010935550.25
 1141750006/11/010950511
 1141750006/12/011000492
 1141750006/13/010955520.25
 1141750006/14/010950481
 1141750006/15/010930493
 1141750006/18/010955463
 1141750006/19/010950461
 1141750006/20/010940461
 1141750006/21/010930471
 1141750006/22/010915462
 1141750006/25/010945433
 1141750006/26/010930472
 1141750006/27/010930511
 1141750006/28/010930552
 1141750006/29/010950521
 1141750007/02/010935432
 1141750007/06/010930382
 1141750007/09/010930463
 1141750007/10/010940441
 1141750007/11/010930421
 1141750007/12/010915411
 1141750007/16/010940431
 1141750007/17/010950403
 1141750007/18/010935381
 1141750007/19/010950381
 1141750007/20/010930355
 1141750007/21/011230355
 1141750007/23/011030332
 1141750007/24/011000352
 1141750007/25/010930351
 1141750007/26/010930341
 1141750007/27/010930330.25
 1141750007/30/010955322
 1141750007/31/010930332
 1141750008/01/010945342
 1141750008/03/010805331
 1141750008/06/011015331
 1141750008/07/010855331
 1141750008/15/010915321
 1141750008/21/010900320.25
 1141750008/29/010935322
 1141750009/05/010905321
 1141750009/05/010905312
 1141750009/11/010825322
 1141750009/21/010955332
 1141750009/27/011000362
 1141750009/30/010233351
 1141750010/03/011015341
 1141750010/10/011000311
 1141750010/24/011010311
 1141750010/30/011000422
 1141750010/31/010935864
 1141750011/01/011305533
 1141750011/02/011015422
 1141750011/07/010955361
 1141750011/13/01131017838
 1141750011/14/010805897
 1141750011/26/0109451678
 1141750011/27/0112301062
 1141750011/28/011000873
 1141750011/29/0109251283
 1141750011/30/0110001568
 1141750012/03/01094589028
 1141750012/04/01122536911
 1141750012/05/0109302754
 1141750012/06/01122542813
 1141750012/07/0112153925
 1141750012/11/0112251712
 1141750012/12/0109451482
 1141750012/13/0109301321
 1141750012/14/01093039415
 1141750012/15/01090525710
 1141750012/18/01093559315
 1141750012/19/0112303373
 1141750012/20/0109304158
 1141750012/21/01113543919
 1141750012/26/0109202594
 1141750012/27/0112202621
 1141750012/28/0109152942
 1141750012/29/01084070929
 1141750012/31/010910177097
 1141750012/31/011300158051
 1141750012/31/011400151040
 1141750012/31/011500145035
 1141750012/31/011600140032
 1141750001/03/021225130014
 1141750001/04/0209107948
 1141750001/08/0209156655
 1141750001/09/0209155525
 1141750001/09/0209155524
 1141750001/10/0212204602
 1141750001/11/0209404066
 1141750001/14/0209203072
 1141750001/14/0209203073
 1141750001/15/0209302851
 1141750001/16/0209452622
 1141750001/17/0209402462
 1141750001/17/0209402461
 1141750001/18/0212102271
 1141750001/22/0209502271
 1141750001/23/0209201891
 1141750001/23/0209201892
 1141750001/24/0209301891
 1141750001/25/0209301812
 1141750001/28/0209202675
 1141750001/28/0209202673
 1141750001/29/0209302333
 1141750001/30/0209352152
 1141750001/31/0209402083
 1141750001/31/0209402082
 1141750002/04/0209351691
 1141750002/11/0210202332
 1141750002/12/0209202262
 1141750002/13/0209402241
 1141750002/13/0209402242
 1141750002/14/0210452332
 1141750002/15/0210302291
 1141750002/19/0209202855
 1141750002/19/0209202857
 1141750002/20/0209152000213
 1141750002/21/020920107015
 1141750002/22/0209207396
 1141750002/22/0209207396
 1141750002/25/0209204543
 1141750002/26/0209154112
 1141750002/27/0209253851
 1141750002/28/0209303651
 1141750002/28/0209303650.25
 1141750003/01/0209203382
 1141750003/04/0209102770.25
 1141750003/05/0209002670.25
 1141750003/06/02123060644
 1141750003/06/02125560328
 1141750003/06/02125560330
 1141750003/07/020910128050
 1141750003/07/021225125035
 1141750003/08/020905107023
 1141750003/08/020905107050
 1141750003/08/02121599889
 1141750003/11/02091074710
 1141750003/11/0209107479
 1141750003/12/0209206545
 1141750003/12/0209206545
 1141750003/13/0208556032
 1141750003/13/0208556034
 1141750003/14/0209105324
 1141750003/14/0209105325
 1141750003/15/0209154664
 1141750003/15/02091546610
 1141750003/18/0209203902
 1141750003/18/0209203902
 1141750003/19/02092039034
 1141750003/19/02092039033
 1141750003/20/0209103656
 1141750003/20/0209103655
 1141750003/21/0209103583
 1141750003/21/0209103584
 1141750003/22/0209203603
 1141750003/22/0209203603
 1141750003/24/020915126064
 1141750003/24/020915126055
 1141750003/25/02102081813
 1141750003/25/02102081814
 1141750003/26/0209256656
 1141750003/26/0209256657
 1141750003/27/0209205805
 1141750003/27/0209205804
 1141750003/28/0209105327
 1141750003/28/0209105325
 1141750003/29/0209105413
 1141750003/29/0209105413
 1141750004/02/0209255322
 1141750004/02/0209255323
 1141750004/03/0209155463
 1141750004/03/0209155464
 1141750004/04/0209205592
 1141750004/04/0209205593
 1141750004/05/0209205432
 1141750004/05/0209205432
 1141750004/08/0209154392
 1141750004/08/0209154393
 1141750004/09/0209254185
 1141750004/09/0209254183
 1141750004/10/0209104483
 1141750004/10/0209104483
 1141750004/11/0209104282
 1141750004/11/0209104282
 1141750004/15/0209204483
 1141750004/15/0209204483
 1141750004/16/0209053522
 1141750004/16/0209053522
 1141750004/17/0209203562
 1141750004/17/0209203562
 1141750004/18/0209103465
 1141750004/18/0209103460.25
 1141750004/19/0209203123
 1141750004/19/02092031210
 1141750004/22/0208552801
 1141750004/22/0208552801
 1141750004/23/0209202823
 1141750004/23/0209202822
 1141750004/24/0209052801
 1141750004/24/0209052803
 1141750004/25/0209152792
 1141750004/25/0209152793
 1141750004/26/0209052793
 1141750004/26/0209052793
 1141750004/30/0209252652
 1141750004/30/0209252650.25
 1141750005/01/0209002320.25
 1141750005/01/0209002321
 1141750005/02/0209152290.25
 1141750005/02/0209152291
 1141750005/03/0208552244
 1141750005/03/0208552241
 1141750005/06/0209152236
 1141750005/06/0209152234
 1141750005/07/0209152272
 1141750005/07/0209152272
 1141750005/08/0209202361
 1141750005/08/0209202361
 1141750005/09/0209202121
 1141750005/09/0209202121
 1141750005/10/0209052040.25
 1141750005/10/0209052041
 1141750005/13/0208551961
 1141750005/13/0208551962
 1141750005/14/0209201940.25
 1141750005/14/0209201940.25
 1141750005/15/0209151900.25
 1141750005/15/02091519010
 1141750005/16/0209301860.25
 1141750005/16/0209301860.25
 1141750005/17/0209201800.25
 1141750005/17/0209201801
 1141750005/20/0209152189
 1141750005/20/0209152183
 1141750005/21/02093043924
 1141750005/21/02093043928
 1141750005/22/0209153832
 1141750005/22/0209153832
 1141750005/23/02093572712
 1141750005/23/02093572711
 1141750005/24/0209106985
 1141750005/24/0209106984
 1141750005/28/0209154330.25
 1141750005/28/0209154331
 1141750005/29/0209202437
 1141750005/29/0209202436
 1141750005/30/0209051963
 1141750005/30/0209051963
 1141750005/31/0209154633
 1141750005/31/0209154634
 1141750006/04/0211304451
 1141750006/04/0211304451
 1141750006/06/0211303882
 1141750006/06/0211303881
 1141750006/10/020920991
 1141750006/10/020920991
 1141750006/11/020925982
 1141750006/11/020925980.25
 1141750006/12/020910922
 1141750006/12/020910922
 1141750006/13/020930871
 1141750006/13/020930871
 1141750006/14/020920801
 1141750006/14/020920802
 1141750006/18/020930793
 1141750006/18/020930792
 1141750006/19/020830790.25
 1141750006/19/020830791
 1141750006/20/020830781
 1141750006/20/020830782
 1141750006/21/020810741
 1141750006/21/020810742
 1141750006/24/020920722
 1141750006/24/020920723
 1141750006/25/020920702
 1141750006/25/020920703
 1141750006/27/020910671
 1141750006/27/020910671
 1141750006/28/020900671
 1141750006/28/020900674
 1141750011/05/021018431
 1141750011/05/021018431
 1141750011/07/021110540.25
 1141750011/07/021110541
 1141750011/07/021300560.25
 1141750011/07/021300562
 1141750011/07/021500604
 1141750011/07/021500602
 1141750011/07/021630641
 1141750011/07/021630641
 1141750011/08/021040280133
 1141750011/08/021040280134
 1141750011/08/021150338125
 1141750011/08/021150338121
 1141750011/08/02140040978
 1141750011/08/02140040985
 1141750011/08/02153039769
 1141750011/08/02153039770
 1141750011/09/02084546339
 1141750011/09/02084546332
 1141750011/09/02104541732
 1141750011/09/02104541731
 1141750011/12/0213351639
 1141750011/12/0213351638
 1141750011/13/0209001206
 1141750011/13/0209001203
 1141750011/15/020915862
 1141750011/15/020915864
 1141750011/18/020850702
 1141750011/18/020850702
 1141750011/20/020930670.25
 1141750011/20/020930671
 1141750011/22/020905642
 1141750011/22/020905641
 1141750011/25/020900620.25
 1141750011/25/020900621
 1141750011/27/020835583
 1141750011/27/020835580.25
 1141750012/02/020900580.25
 1141750012/02/020900580.25
 1141750012/04/020850580.25
 1141750012/04/020850582
 1141750012/06/020855571
 1141750012/06/020855571
 1141750012/09/020845560.25
 1141750012/09/020845560.25
 1141750012/11/020840992
 1141750012/11/020840992
 1141750012/13/020840804
 1141750012/13/020840802
 1141750012/13/021040879
 1141750012/13/021040872
 1141750012/13/0212401014
 1141750012/13/0212401013
 1141750012/13/02144514719
 1141750012/13/02144514723
 1141750012/13/02160022163
 1141750012/13/02160022163
 1141750012/14/020800179044
 1141750012/14/0208001790141
 1141750012/14/021148162096
 1141750012/14/021148162074
 1141750012/14/021440149092
 1141750012/14/021440149084
 1141750012/15/0207401790188
 1141750012/15/0207401790191
 1141750012/15/0209401620138
 1141750012/15/0209401620143
 1141750012/15/0211401500110
 1141750012/15/021140150056
 1141750012/15/021340133055
 1141750012/15/021340133056
 1141750012/15/021615116042
 1141750012/15/021615116042
 1141750012/16/0210004600401
 1141750012/16/0210004600374
 1141750012/16/0212153650304
 1141750012/16/0212153650360
 1141750012/16/0214153110244
 1141750012/16/0214153110237
 1141750012/16/0215003010209
 1141750012/16/0215003010198
 1141750012/17/020930124030
 1141750012/17/020930124031
 1141750012/17/021100117027
 1141750012/17/021100117028
 1141750012/17/021300109026
 1141750012/17/021300109024
 1141750012/17/021500102023
 1141750012/17/021500102024
 1141750012/17/02163095625
 1141750012/17/02163095623
 1141750012/18/02083061513
 1141750012/18/0208306159
 1141750012/18/02103059510
 1141750012/18/02103059512
 1141750012/18/02123056010
 1141750012/18/02123056011
 1141750012/20/0209003904
 1141750012/20/0209003903
 1141750012/23/0209003318
 1141750012/23/0209003317
 1141750012/27/0209303054
 1141750012/27/0209303053
 1141750012/30/02091083418
 1141750012/30/02091083416
 1141750012/30/02150076511
 1141750012/30/02150076511
 1141750001/03/0309204932
 1141750001/03/0309204932
 1141750001/06/0309104322
 1141750001/06/0309104323
 1141750001/08/0309003661
 1141750001/08/0309003662
 1141750001/10/0309004825
 1141750001/10/0309004825
 1141750001/13/0309305447
 1141750001/13/0309305446
 1141750001/15/0310304192
 1141750001/15/0310304193
 1141750001/17/0310303271
 1141750001/17/0310303271
 1141750001/21/0309053010.25
 1141750001/21/0309053012
 1141750001/23/03092074223
 1141750001/23/03092074223
 1141750001/27/0309204712
 1141750001/27/0309204712
 1141750001/31/0309303562
 1141750001/31/0309303562
 1141750002/03/0309553201
 1141750002/03/0309553200.25
 1141750002/05/0310002750.25
 1141750002/05/0310002751
 1141750002/07/0309302460.25
 1141750002/07/0309302460.25
 1141750002/10/0311402111
 1141750002/10/0311402111
 1141750002/12/0311051990.25
 1141750002/12/0311051990.25
 1141750002/14/03101550116
 1141750002/14/03101550118
 1141750002/15/0313202952
 1141750002/15/0313202951
 1141750002/15/0315002911
 1141750002/15/0315002911
 1141750002/15/0317002882
 1141750002/15/0317002883
 1141750002/16/03070066134
 1141750002/16/03070066133
 1141750002/16/030945636162
 1141750002/16/030945636168
 1141750002/16/031225661243
 1141750002/16/0314006435
 1141750002/16/03140064312
 1141750002/16/0315306336
 1141750002/16/0315306339
 1141750002/17/0307004470.25
 1141750002/17/0307004471
 1141750002/17/0309004379
 1141750002/17/0309004379
 1141750002/17/0311004297
 1141750002/17/0311004296
 1141750002/17/0313004196
 1141750002/17/0313004197
 1141750002/17/0315004072
 1141750002/17/0315004072
 1141750002/18/0309003523
 1141750002/18/0309003522
 1141750002/18/0311003451
 1141750002/18/0311003452
 1141750002/19/0309153121
 1141750002/19/0309153123
 1141750002/21/0309152882
 1141750002/21/0309152883
 1141750002/24/0309002333
 1141750002/24/0309002334
 1141750002/26/0309002142
 1141750002/26/0309002142
 1141750002/28/0309002082
 1141750002/28/0309002082
 1141750003/05/0308501702
 1141750003/05/0308501701
 1141750003/07/0308451592
 1141750003/07/0308451594
 1141750003/10/0309401466
 1141750003/10/0309401463
 1141750003/12/0311001462
 1141750003/12/0311001462
 1141750003/13/0313001501
 1141750003/13/03130015013
 1141750003/13/0315001532
 1141750003/13/0315001533
 1141750003/14/0307302183
 1141750003/14/0307302183
 1141750003/14/0309302635
 1141750003/14/0309302633
 1141750003/14/0312103039
 1141750003/14/03121030312
 1141750003/14/03140034010
 1141750003/14/0314003407
 1141750003/14/03153039544
 1141750003/14/03153039540
 1141750003/14/031530395112
 1141750003/14/031530395120
 1141750003/15/0307302170623
 1141750003/15/0307302170577
 1141750003/15/0309302540393
 1141750003/15/0309302540330
 1141750003/15/0311302790392
 1141750003/15/0311302790385
 1141750003/15/0313303160334
 1141750003/15/0313303160353
 1141750003/15/0315302810191
 1141750003/15/0315302810182
 1141750003/16/030800111019
 1141750003/16/030800111019
 1141750003/16/031000105020
 1141750003/16/031000105022
 1141750003/16/03122598318
 1141750003/16/03122598318
 1141750003/16/03140092913
 1141750003/16/03140092917
 1141750003/16/03163088511
 1141750003/16/03163088512
 1141750003/17/0308306866
 1141750003/17/0308306869
 1141750003/19/0309104373
 1141750003/19/0309104372
 1141750003/21/0310004343
 1141750003/21/0310004344
 1141750003/24/0309305414
 1141750003/24/0309305414
 1141750003/26/0309204343
 1141750003/26/0309204344
 1141750003/28/0309104871
 1141750003/28/0309104872
 1141750004/03/0310004099
 1141750004/03/0310004097
 1141750004/09/0309054422
 1141750004/09/0309054423
 1141750004/11/0309254221
 1141750004/11/0309254221
 1141750004/14/030900119023
 1141750004/14/030900119021
 1141750004/16/0308507384
 1141750004/16/0308507384
 1141750004/18/0309007084
 1141750004/18/0309007082
 1141750004/21/0309256293
 1141750004/21/0309256293
 1141750004/23/0308555762
 1141750004/23/0308555762
 1141750004/28/030925119012
 1141750004/28/030925119021
 1141750004/30/030910102011
 1141750004/30/030910102013
 1141750005/02/0308558514
 1141750005/02/0308558514
 1141750005/05/030930133012
 1141750005/05/030930133010
 1141750005/06/03085011405
 1141750005/06/03085011406
 1141750005/07/0309309655
 1141750005/07/0309309653
 1141750005/08/030910122013
 1141750005/08/030910122010
 1141750005/09/030850121016
 1141750005/09/030850121015
 1141750005/14/03093010405
 1141750005/14/03093010404
 1141750005/16/03085510502
 1141750005/16/03085510502
 1141750005/19/0309258723
 1141750005/19/0309258722
 1141750005/21/03092510904
 1141750005/21/03092510905
 1141750005/22/03115511605
 1141750005/22/03115511606
 1141750005/23/030940141012
 1141750005/23/030940141010
 1141750005/27/03091014606
 1141750005/27/03091014605
 1141750005/29/030855193024
 1141750005/29/030855193021
Table A1c (View this table on a separate page.) Suspended-sediment concentration samples and associated instantaneous streamflow for the Yuba River below New Colgate Powerplant near French Corral (YRC) collected during water years 2001, 2002, and 2003
[USGS Marina sediment laboratory uses 0.5 mg/L (milligram per liter) as the detection limit for reporting suspended-sediment concentration (SSC); therefore, samples with SSC of less than 0.5 mg/L are reported as 0.25 mg/L (Helsel and Hirsch, 1992). ft3/s, cubic feet per second]
Map identifierStation identifierDateTimeInstantaneous streamflow (ft³/s)Suspended-sediment concentration (mg/L)
YRC1141370001/09/0114301073
 1141370001/11/01161021365
 1141370001/12/0113351208
 1141370001/19/0111458211
 1141370001/22/0111057716
 1141370001/23/0112357753
 1141370001/24/01130015561
 1141370001/25/01122034008
 1141370001/26/0112201434
 1141370001/29/0112301072
 1141370001/30/011225102106
 1141370002/01/0112251252
 1141370002/02/0112151341
 1141370002/05/0112258614
 1141370002/07/011215864
 1141370002/08/011225842
 1141370002/09/011220868
 1141370002/11/011250257303
 1141370002/12/01121017519
 1141370002/13/0112151347
 1141370002/15/0112101122
 1141370002/16/0112051041
 1141370002/19/0112051252
 1141370002/20/01122528128
 1141370002/22/01121540216
 1141370002/23/0112152397
 1141370002/26/0112301656
 1141370002/28/01122020604
 1141370002/28/0116007785
 1141370003/02/0112201656
 1141370003/05/01122025210
 1141370003/07/01124510307
 1141370003/09/0111551522
 1141370003/12/0112151206
 1141370003/14/0111551281175
 1141370003/15/0113151095
 1141370003/16/0112251077
 1141370003/19/01121533802
 1141370003/21/0112351044
 1141370003/26/010915469313
 1141370003/28/01122513902
 1141370003/30/0112354383
 1141370004/02/0112304382
 1141370004/04/0112204203
 1141370004/06/01123599.61
 1141370004/06/01123599.64
 1141370004/09/0112301151
 1141370004/09/0112301151
 1141370004/11/0112301252
 1141370004/11/0112301252
 1141370004/13/0112158511
 1141370004/13/0112158511
 1141370004/16/01122021502
 1141370004/16/01122021505
 1141370004/18/0112301342
 1141370004/18/0112301341
 1141370004/20/01123014405
 1141370004/20/01123014401
 1141370004/23/0112257182
 1141370004/23/0112257181
 1141370004/25/01122020302
 1141370004/25/011220203020
 1141370004/30/01121520402
 1141370005/02/0112451232
 1141370005/04/01123020002
 1141370005/07/01123018401
 1141370005/09/01121525301
 1141370005/11/01120031202
 1141370005/14/01121516601
 1141370005/16/01122594319
 1141370005/18/01120025302
 1141370005/21/01120017801
 1141370005/22/01120524902
 1141370005/23/01121013201
 1141370005/25/0112158874
 1141370005/29/01121520203
 1141370005/31/01122027502
 1141370006/04/01120012402
 1141370006/06/01121514902
 1141370006/08/01121021202
 1141370006/11/01121512601
 1141370006/14/01122019001
 1141370006/18/01122527703
 1141370006/20/0112208603
 1141370006/22/01105027001
 1141370006/25/0112256932
 1141370006/27/01123026300
 1141370006/29/01121512401
 1141370007/02/01120518908
 1141370007/06/01123028904
 1141370007/09/01121524701
 1141370007/11/01120032601
 1141370007/13/01121028005
 1141370007/16/011235272024
 1141370007/18/01122023001
 1141370007/20/01121021808
 1141370007/23/01131524202
 1141370007/25/01125033401
 1141370007/27/01121518102
 1141370007/30/01123528202
 1141370008/01/01122015302
 1141370008/02/01121031701
 1141370008/06/01124535003
 1141370008/15/01150033008
 1141370008/21/01112034201
 1141370008/29/011215313012
 1141370009/11/011035218030
 1141370009/21/01124016003
 1141370009/27/0112207013
 1141370010/03/01130018104
 1141370010/10/0112258962
 1141370010/17/0111458784
 1141370010/24/01124524203
 1141370010/30/01124015802
 1141370010/31/01134012404
 1141370011/02/011220420113
 1141370011/07/0112359632
 1141370011/13/01103018603
 1141370011/16/0112551173
 1141370011/26/01122010304
 1141370011/27/01100010102
 1141370011/28/0112159722
 1141370011/29/011140117111
 1141370012/03/01122527123
 1141370012/05/0112182613
 1141370012/06/01092555620
 1141370012/07/0109152346
 1141370012/11/0109301236
 1141370012/12/0112051151
 1141370012/14/01122529114
 1141370012/15/0111451695
 1141370012/18/0112253068
 1141370012/19/0109301974
 1141370012/20/0112303013
 1141370012/26/0112151497
 1141370012/28/0111401347
 1141370012/31/0111051170105
 1141370001/02/0213305085
 1141370001/04/0211353014
 1141370001/09/0211452430
 1141370001/09/02114524313
 1141370001/11/0212201942
 1141370001/14/02115520902
 1141370001/16/021230255014
 1141370001/16/02123025501
 1141370001/17/02124527702
 1141370001/22/0212456774
 1141370001/24/02120511101
 1141370001/24/02120511101
 1141370001/28/0212459634
 1141370001/30/02122016402
 1141370002/04/0212509531
 1141370002/04/0212509532
 1141370002/11/02121011803
 1141370002/13/02124010605
 1141370002/15/02123010702
 1141370002/15/02123010703
 1141370002/21/0212155422
 1141370002/22/0212052814
 1141370002/22/02120528122
 1141370002/25/02121014906
 1141370002/26/021215104017
 1141370002/28/0212106073
 1141370003/01/0212055856
 1141370003/04/02115013003
 1141370003/05/02121012403
 1141370003/05/02121012401
 1141370003/11/02121028002
 1141370003/11/021210280012
 1141370003/12/02115523404
 1141370003/12/02115523402
 1141370003/14/02120010606
 1141370003/14/02120010602
 1141370003/15/02121013903
 1141370003/15/021210139018
 1141370003/18/02120023703
 1141370003/18/021200237018
 1141370003/19/02121019502
 1141370003/19/02121019504
 1141370003/22/02121021803
 1141370003/22/02121021802
 1141370003/24/02113015808
 1141370003/24/021130158010
 1141370003/25/02121027303
 1141370003/25/021210273016
 1141370003/26/02121023402
 1141370003/26/021210234030
 1141370003/28/02120021901
 1141370003/28/02120021905
 1141370003/29/02120529003
 1141370003/29/02120529004
 1141370004/03/0212002720155
 1141370004/03/02120027202
 1141370004/05/02120520702
 1141370004/05/02120520702
 1141370004/08/02121531303
 1141370004/08/021215313010
 1141370004/09/02122030401
 1141370004/09/02122030401
 1141370004/11/02115524405
 1141370004/11/02115524400
 1141370004/15/02120026501
 1141370004/15/02120026501
 1141370004/16/02115533201
 1141370004/16/02115533202
 1141370004/18/02115525805
 1141370004/18/02115525802
 1141370004/19/02122532602
 1141370004/19/02122532602
 1141370004/22/02114525808
 1141370004/22/02114525803
 1141370004/23/021205352016
 1141370004/23/02120535201
 1141370004/25/02121032605
 1141370004/25/02121032601
 1141370004/26/021155296012
 1141370004/26/02115529601
 1141370004/30/02124029701
 1141370004/30/02124029703
 1141370005/02/02115031001
 1141370005/02/02115031004
 1141370005/03/02115532803
 1141370005/03/02115532802
 1141370005/06/02114533002
 1141370005/06/02114533004
 1141370005/07/02120532802
 1141370005/07/02120532803
 1141370005/09/02121033006
 1141370005/09/02121033003
 1141370005/10/02115032301
 1141370005/10/02115032302
 1141370005/13/021145no data1
 1141370005/13/021145no data4
 1141370005/14/021210no data2
 1141370005/14/021210no data1
 1141370005/16/02115019902
 1141370005/16/02115019902
 1141370005/17/02120018601
 1141370005/17/02120018602
 1141370005/20/02120521903
 1141370005/20/02120521902
 1141370005/21/02120525805
 1141370005/21/02120525802
 1141370005/23/02121023901
 1141370005/23/02121023902
 1141370005/24/02121027802
 1141370005/24/02121027802
 1141370005/28/02120031302
 1141370005/28/02120031301
 1141370005/30/02113025202
 1141370005/30/021130252013
 1141370005/31/02121026200
 1141370005/31/02121026201
 1141370006/04/02153031902
 1141370006/04/02153031901
 1141370006/06/02150034002
 1141370006/06/02150034001
 1141370006/10/02121017401
 1141370006/10/02121017401
 1141370006/11/02120526005
 1141370006/11/02120526001
 1141370006/13/02121511302
 1141370006/13/02121511302
 1141370006/14/02120529202
 1141370006/14/02120529203
 1141370006/17/02121532402
 1141370006/17/02121532403
 1141370006/18/021205362011
 1141370006/18/02120536200
 1141370006/20/02115525202
 1141370006/20/02115525201
 1141370006/21/02112534401
 1141370006/21/02112534403
 1141370006/24/02121025302
 1141370006/24/02121025303
 1141370006/28/02120029701
 1141370006/28/02120029702
Table A1d (View this table on a separate page.) Suspended-sediment concentration samples and associated instantaneous streamflow for the Yuba River below Englebright Dam near Smartville (YRE) collected during water years 2001, 2002, and 2003
[USGS Marina sediment laboratory uses 0.5 mg/L (milligram per liter) as the detection limit for reporting suspended-sediment concentration (SSC); therefore, samples with SSC of less than 0.5 mg/L are reported as 0.25 mg/L (Helsel and Hirsch, 1992). ft3/s, cubic feet per second]
Map identifierStation identifierDateTimeInstantaneous Streamflow (ft³/s)Suspended-sediment Concentration (mg/L)
YRE1141800001/12/0115009412
 1141800002/02/0115007012
 1141800002/06/0109306881
 1141800002/10/0114406566
 1141800002/12/0114106922
 1141800002/13/0114006912
 1141800002/15/0114056912
 1141800002/16/0114006922
 1141800002/20/0114206903
 1141800002/22/01140012401
 1141800002/23/01140512201
 1141800002/27/01125010401
 1141800002/28/0111309464
 1141800003/06/0113107386
 1141800003/08/0112557453
 1141800003/13/0112457343
 1141800003/14/0113357313
 1141800003/15/0112507282
 1141800003/20/01124572110
 1141800003/21/0111307217
 1141800003/27/0109257254
 1141800004/03/01125010904
 1141800004/05/01125510852
 1141800004/10/01130010701
 1141800004/10/01130010701
 1141800004/12/01125010703
 1141800004/12/01125010703
 1141800004/17/011310no data8
 1141800004/17/011310no data2
 1141800004/19/011250no data1
 1141800004/19/011250no data1
 1141800004/24/0113058801
 1141800004/24/0113058801
 1141800004/26/0112558851
 1141800004/26/0112558851
 1141800005/01/0112508753
 1141800005/03/0112459943
 1141800005/08/01125511905
 1141800005/10/01125511302
 1141800005/15/0112559003
 1141800005/17/0112508502
 1141800005/24/0112458801
 1141800005/30/0110009722
 1141800005/30/0112459783
 1141800006/01/0112409461
 1141800006/05/0112459722
 1141800006/07/0112509724
 1141800006/13/0112559462
 1141800006/15/0112459723
 1141800006/19/01121510202
 1141800006/21/01121510401
 1141800006/21/01123010404
 1141800006/26/0112459943
 1141800006/28/0112509051
 1141800007/03/0112459621
 1141800007/05/01115019205
 1141800007/10/01132020902
 1141800007/12/01131521201
 1141800007/17/01130021006
 1141800007/19/01130021301
 1141800007/24/01131521203
 1141800007/26/01130021202
 1141800007/31/01123521101
 1141800008/03/01110020001
 1141800008/07/01120019301
 1141800008/15/01130519002
 1141800008/21/01124519201
 1141800008/29/0113408121
 1141800008/30/0116008120.25
 1141800009/05/0112458122
 1141800009/11/0112056001
 1141800009/27/0114206282
 1141800009/30/0123306732
 1141800010/03/0115105542
 1141800010/10/0113006732
 1141800010/17/0114006565
 1141800010/24/0110308952
 1141800010/25/0110208752
 1141800011/06/011015no data3
 1141800011/27/011500no data 1
 1141800011/29/0110007342
 1141800012/04/01094012754
 1141800012/13/0110006245
 1141800012/13/0113006249
 1141800012/15/0111156284
 1141800012/27/0109208264
 1141800001/03/02092516408
 1141800001/04/02122015709
 1141800001/04/02122015708
 1141800001/08/02123019608
 1141800001/10/02093019605
 1141800001/15/02124019703
 1141800001/15/02124019704
 1141800001/18/02092019853
 1141800001/23/02123016102
 1141800001/25/02122016103
 1141800001/25/02122016103
 1141800001/29/02124016103
 1141800002/05/02093016005
 1141800002/14/02130515702
 1141800002/14/02130515701
 1141800002/20/02125015902
 1141800002/27/02125515807
 1141800003/05/02103015709
 1141800003/13/021235no data7
 1141800003/13/021235no data8
 1141800003/20/02123021406
 1141800003/20/02123021404
 1141800003/27/02124521605
 1141800003/27/02124521606
 1141800004/02/02100021406
 1141800004/10/02115521403
 1141800004/10/02115521402
 1141800004/12/02143021503
 1141800004/12/02143021502
 1141800004/12/02143021502
 1141800004/12/02143021501
 1141800004/12/02143021502
 1141800004/17/02123521401
 1141800004/24/02122521401
 1141800004/24/02122521401
 1141800005/01/02121022702
 1141800005/01/02121022702
 1141800005/03/02100022801
 1141800005/08/02124524002
 1141800005/08/02124524003
 1141800005/15/02124520601
 1141800005/15/02124520601
 1141800005/22/02124020002
 1141800005/22/02124020002
 1141800005/29/02124019952
 1141800005/29/02124019953
 1141800006/07/02104520102
 1141800006/07/02104520100.25
 1141800006/12/02103020002
 1141800006/12/02124520002
 1141800006/12/02124520001
 1141800006/19/02114520100.25
 1141800006/19/02114520102
 1141800006/27/02123021701
 1141800006/27/02123021701
 1141800011/01/0212579511
 1141800011/01/0212579511
 1141800011/01/0213009511
 1141800011/11/021010no data0.25
 1141800011/12/021225no data1
 1141800011/12/02122500no data0.25
 1141800011/25/021230no data2
 1141800011/25/021230no data2
 1141800012/04/021220no data0.25
 1141800012/04/021220no data1
 1141800012/11/021235no data3
 1141800012/11/021235no data2
 1141800012/20/021215104030
 1141800012/20/021215104033
 1141800012/23/021300108033
 1141800012/23/021300108034
 1141800012/30/021350236011
 1141800012/30/021350236011
 1141800001/08/03114512909
 1141800001/08/03114512908
 1141800001/16/031245193019304
 1141800001/16/03124519304
 1141800001/23/031200no data3
 1141800001/23/031200no data3
 1141800002/05/03121524104
 1141800002/05/03121524103
 1141800002/14/03123020003
 1141800002/14/03123020002
 1141800002/17/03115020102
 1141800002/17/03115020102
 1141800002/28/03122020207
 1141800002/28/03122020203
 1141800003/07/03121520304
 1141800003/07/03121520304
 1141800003/12/03123020302
 1141800003/12/03123020302
 1141800003/15/03112048101
 1141800003/15/03112048100.25
 1141800003/15/03133053004
 1141800003/15/03133053002
 1141800003/16/031000295012
 1141800003/16/03100029502
 1141800003/16/03130033704
 1141800003/16/03130033703
 1141800003/16/03161539603
 1141800003/16/03161539602
 1141800003/17/031045420016
 1141800003/17/031045420015
 1141800003/21/031145no data9
 1141800003/21/031145no data9
 1141800004/08/031400no data1
 1141800004/08/031400no data2
 1141800004/15/03093034807
 1141800004/15/03093034805
 1141800004/22/03095518005
 1141800004/22/03095518004
 1141800005/02/031155no data5
 1141800005/02/031155no data6
 1141800005/05/031155no data6
 1141800005/05/031155no data6
 1141800005/16/031220no data2
 1141800005/16/031220no data1
 1141800005/22/030948no data1
 1141800005/22/030948no data1
 1141800005/27/03143049202
 1141800005/27/03143049202
 1141800005/29/03123057101
 1141800005/29/03123057102

Appendix 2.

Table A2 (View this table on a separate page.) Grain-size distributions of the less-than 0.063 size fraction for suspended sediment collected during water year 2003.
[Numbers in each column represent percentage of total suspended-sediment mass finer than indicated size, but coarser than size in next column to right. mm, millimeter; ø, unit of measure used in grain size analysis]
    Suspended-sediment grain size distribution       
Map identifierStation identifierDateTime0.0625 mm (4 ø)0.0441 mm (4.5 ø)0.0313 mm (5 ø)0.0221 mm (5.5 ø)0.0156 mm (6 ø)0.0110 mm (6.5 ø)0.0078 mm (7 ø)0.0055 mm (7.5 ø)0.0039 mm (8 ø)0.0028 mm (8.5 ø)0.0020 mm (9 ø)0.0014 mm (9.5 ø)0.0098 mm (10 ø)0.0069 mm (10.5 ø)0.0049 mm (11 ø)0.0035 mm (11.5 ø)
MYG1141000011/08/0215201.39000.031.162.754.218.7113.4115.5814.311.739.968.976.021.77
 1141000011/09/02081700000.292.174.669.6814.516.314.611.79.98.75.81.7
 1141000012/14/0210006.85.848.419.6310.0110.019.648.977.826.485.053.913.052.481.530.38
 1141000012/15/02073000.834.145.737.49.411.11211.810.58.36.45.142.60.7
 1141000012/17/0213252.220.972.774.577.2110.4712.9113.512.5210.287.535.394.013.131.960.59
 1141000012/18/021000000.022.035.928.1312.314.714.9139.975.13.92.40.7
 1141000012/30/021200000.65710.059.310.511.611.710.996.95.342.40.7
 1141000002/16/0308000.9800.854.596.248.2210.211.5911.9811.099.217.626.735.743.861.09
 1141000002/16/03080000.344.965.24.46.91012.613.912.810.17.153.72.40.6
 1141000002/17/031400000.043.246.25.827.91113.513.711.89.27.25.73.71
 1141000002/17/03140000.925.315.5789.910.91212.211.18.86.34.22.81.60.4
 1141000002/17/031400000.542.763.464.246.710.213.313.8129.98.77.75.21.5
 1141000003/14/03150002.184.227.37.296.787.59.1710.3210.228.967.826.986.054.061.15
 1141000003/15/0315457.854.036.638.329.319.89.89.418.317.035.454.463.763.172.080.59
 1141000003/15/0315457.13.096.098.049.159.9110.099.728.887.385.84.673.923.362.160.65
 1141000003/16/03153000.332.135.246.167.99.9111.211.6110.99.417.86.95.713.71.1
 1141750011/08/0210220.350.12.465.076.629.1710.9612.0612.0610.868.776.985.784.783.090.9
SYG1141750012/13/021422000.424.966.126.38.210.212.212.911.69.47.45.73.61
 1141750012/14/0208009.191.83.424.495.797.829.9311.2211.039.657.545.794.794.132.670.74
 1141750012/15/0214156.211.44.025.257.29.6511.5512.1211.179.577.195.213.983.031.890.57
 1141750012/16/02143517.92.034.25.997.839.7710.8310.579.247.135.113.342.551.941.230.35
 1141750012/18/02094016.62.34.85.957.198.519.329.48.797.546.034.73.642.931.780.53
 1141750012/30/02160010.640.191.986.038.428.589.9210.8110.729.657.695.724.23.131.790.54
 1141750012/31/0211301.2200.011.424.928.1712.7415.4115.5113.149.586.624.743.652.170.69
 1141750002/16/0307006.571.064.576.98.089.029.779.979.598.556.955.925.074.332.810.85
 1141750002/17/0313009.460.413.824.746.248.7810.9611.7711.329.516.975.074.163.622.440.72
 1141750003/14/0316000.79000.475.478.1611.7114.0914.5813.210.427.445.264.373.170.89
 1141750003/14/031600000.051.814.697.351113.41412.510.286.75.63.71
 1141750003/15/03113022.251.172.493.835.487.79.4910.249.588.035.974.513.693.021.970.58
 1141750003/15/03113023.771.262.363.685.167.349.2710.249.838.156.124.443.382.741.780.48
 1141750003/16/0312302.571.485.286.767.999.4510.6210.8210.338.967.115.864.974.292.730.78
YRE1141800003/15/03141000.011.354.766.888.29.21112.411.59.57.66.75.841.1
 1141800003/16/03104500.012.526.396.087.19.611.712.511.497.26.25.53.71.1

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