Fourth of July Creek is a tributary of the Salmon River approximately 14 miles south of Stanley, Idaho. The study reach is about a 520 ft length of stream about 2.9 miles east of Highway 75. The site is on land administered by the Forest Service at an elevation of about 7,300 ft above sea level. The drainage area is 17.1 mi 2 and the geology of the watershed is intrusive igneous and sedimentary.
In 1994 and 1995, personnel of Case Western Reserve University established a stream gage and measured sediment transport and streamflow at this site. Additional information collected at this site include a survey of the stream reach, pebble counts of the substrate surface and transport distance of painted rocks during high flows in 1995.
Figures 1 and 2 show photographs of Fourth of July Creek looking upstream and downstream from the measurement location for stream discharge and sediment transport.
Figure 1. Fourth of July Creek looking upstream from the measurement site.

Figure 2. Fourth of July Creek looking downstream from the measurement site
Streamflow was recorded for water years 1994 and 1995 from the beginning of the spring snowmelt hydrograph until fall. Estimated average annual streamflow (Q the stream is 15.0 ft 3 /s and the estimated bankfull discharge (Q b
) is 137 ft 3 a
) for
/s. Stream discharge was recorded in 1994 from April 30 to October 21. Stream discharge was very low in 1994 and the largest daily mean discharge was only 36.7 ft 3 /s. In 1995, stream discharge was recorded from April 21 to September 30 and the largest daily mean discharge recorded was 129 ft 3 /s on June 27. A portion of the flow is diverted upstream of the study reach. The diversion appears to be less than about 4 ft 3 /s and during 1994 occurred from July 7 to September 20 and in 1995 from August 25 to September 25.

Figure 3 shows the longitudinal profile for the channel bed in the center of the channel, the water surface elevations along each bank at the time of the survey and bankfull flow elevations (floodplains). The average gradient for the study reach is 0.0202 ft/ft.
Cross-sections of the channel were surveyed at five locations.
All but one of the discharge and sediment transport measurements were made at cross-section 2 (XS2) and the movement of painted rocks during the spring and early summer snowmelt flows in
166
164
162
160
Fourth of July Creek
158
156
XS4
154
152
150
Water Surface Elevation Left Edge
Center of Channel Bed Elevation
Water Surface Elevation Right Edge
Bankfull Elevation Left Side
Bankfull Elevation Right Side
XS3 XS2
XS5
Painted Rock
Transects
148
0 100 200 300 400 500
Distance, ft
1995 were measured at two transects about 16 and 52 ft downstream of XS2.
Figure 3. Longitudinal profile of the study reach in Fourth of July Creek.
XS1
170
Fourth of July Creek
Cross-Section 2
165
600
160 Q b
Q a
155
0 10 20 30 40 50 60 70 80
Distance, ft
90 100 110 120 130 140 150
Figure 4. Cross-section of Fourth of July Creek at the sediment transport
measurement site.

Figure 4 shows the cross-section at the sediment transport measurement site, cross-section 2. The channel geometry relationships for this cross-section are shown in
Figure 5. All data collected in 1994 and 1995 were used to develop the power relationships with discharge, with the exception of the June 12, 1994 measurement made at a location about 33 ft upstream of cross-section 2. Over the range of discharges when sediment transport was measured (5.46 to 137 ft 3 /s), estimated stream width, estimated average depth and estimated average velocity varied from 17.5 to 26.8 ft, 0.5 to 1.5 ft, and 0.6 to 3.4 ft/s, respectively. The average reach slope is 0.0202 ft/ft.
100 10
Fourth of July Creek
Top Width y = 14.04x
0.131
R
2
= 0.83
10
1
Average Velocity y = 0.247x
0.534
R
2
= 0.99
Average Depth y = 0.287x
0.336
R
2
= 0.98
1
Average Depth
Top Width
Average Velocity
0.1
1 10 100
0.1
1000
Discharge, ft 3 /s
Figure 5. Width, average depth, and average velocity versus stream discharge
at the predominant measurement site. (Open symbols are for a 6/12/94
measurement at site 33 ft upstream of cross-section 2).

Channel Material
Surface pebble counts were made within 15 ft of cross-section 2 on June 17, 1994.
No subsurface cores were collected at this site. The average D
50 and D
90
for the surface material in the reach were 51 mm and 137 mm, respectively (Figure 6).
100
Fourth of July Creek
90
80
70
60
50
40
30
20
10
0
1 10
Particle Size, mm
100 1000
Figure 6. Particle size distribution for surface material samples in Fourth of July
Creek.

The sediment transport data include 78 measurements of bedload transport and 25 measurements of suspended sediment transport. Sediment transport measurements spanned a range of stream discharges from 5.46 ft 3 /s (0.36Q
a
; 0.04Q
b
) to 137 ft 3
(9.13Q
a
; 1.00Q
b
/s
).
Bedload transport ranged from 0.00034 to 10.4 t/d and suspended transport ranged from 0.0952 to 71.7 t/d.
Over the range of measured discharges, suspended transport accounts for the majority of the material in transport with approximately an order of magnitude greater suspended transport at the lowest discharges and about three times as much at the highest discharges during which sediment transport was measured (Figure 7).
100
Fourth of July Creek
10
1
0.1
Suspended y = 2.258E-04x
2.305
R
2
= 0.90
BCF=1.277
0.01
Total Bedload y = 8.535E-06x
2.733
R
2
= 0.78
BCF=2.347
0.001
Total Bedload
Suspended
Q a
Q b
0.0001
1.0
10.0
100.0
1000.0
Discharge, ft
3
/s
Figure 7. Bedlo ad and suspended load transport rate versus discharge.

The bedload transport rates by size class (Figure 8) shows that the larger rates are associated with material in the 0.5 to 2mm diameter size class. No curve fitting was done for sediment >22.6mm diameter since only eight of the samples contained this size class of material. All discharges transporting material >22.6mm exceeded 68.3 ft 3 /s.
10
Fourth of July Creek
1
<0.5mm
y = 1.505E-05x
2.222
R
2
= 0.73
0.1
0.5 - 2mm y = 6.248E-06x
2.634
R
2
= 0.70
0.01
2 - 8mm y = 1.790E-07x
3.249
R
2
= 0.75
0.001
0.0001
<0.5 mm
0.5-2 mm
2-8 mm
8-22.6 mm
>22.6 mm
Q a
Q b
8 - 22.6mm
y = 6.368E-07x
2.728
R
2
= 0.49
0.00001
1 10 100 1000
Discharge, ft
3
/s
Figure 8. Bedload transport rate versus discharge for selected siz e classes .

The size of the largest particle in the bedload sample increased with discharge
(Figure 9). The largest particle measured in a bedload sample was 40 mm at a discharge of 130 ft 3 /s. There is also a trend of increasing median size of the bedload sample with increasing discharge. The D
50
for most of the bedload samples was in the sand size, 0.5 to 2.0 mm, with only four samples exceeding 2 mm. The largest median diameter of a bedload sample was 3.1 mm. The information on the largest particle in the bedload sample and observations of painted rock movement suggest that discharges at or slightly above the bankfull discharge are capable of moving the median diameter particles on the channel surface.
1000
Fourth of July Creek
Largest
Painted
Rock Moved
1995
100
D
50
of surface substrate
R
2
= 0.75
10
R 2 = 0.52
1
Median Diameter
Largest Particle
Q a
Q b
0.1
1.0
10.0
100.0
1000.0
Discharge, ft
3
/s
Figure 9. M edian size of the bedload sample and the largest particle size versus
stream discharge for Fourth of July Creek.

Painted Rock Transport
A total of forty painted rocks were placed across two transects (twenty per transect) on May 29, 1995. Daily mean discharge on the day of rock placement was 26.7 ft 3 /s. The size of the rocks ranged from 32 to 137 mm diameter (b-axis) which represent the D
24
up to the D
90
of the surface particle size distribution measured at cross-section 2.
Transport of the rocks as of July 5, 1995 are shown in Figures 10 and 11.
45
40
Fourth of July Creek
Painted Rocks
Transect 1
35
30
25
20
15
Particle B-axis, mm
10
5
95 135 101 137 80 97 50 55 62 91 137 46 71 90 41 65 68 78 72 32
M M M M M
0
1.9
7
3.1
2
4.2
6
5.4
1
6.5
6
7.7
1
8.8
6
10.00 11.15 12.30 13.45 14.60 15.74 16.89 18.0
4
Distance Across Stream, ft
19.
19
20
.34
Figure 10. Transport distance of painted rocks at transect 1 .
21
.48
22.63 23.78
35
30
Fourth of July Creek
Painted Rocks
Transect 2
25
20
15
10
Particle B-axis, mm
5
70 75 114 100 49 39 102 44 68 56 38 49 114 76 106 125 70 103 101 68
M M M M M M M M M M
0
1.
80
2.
62
3.
44
4.
26
5.
08
5.
90
6.7
2
7.
54
8.
36
9.1
8
10
.0
0
10
.8
2
11
.6
4
Distance Across Stream, ft
12
.4
6
13
.2
8
14
.1
0
14
.9
2
15
.7
4
16
.5
6
17
.3
8
Figure 11 Transport distance of painted rocks at transect 2.

Twenty two of the forty rocks were found. Of those found, only three had not moved. The maximum transport distance was 42.6 ft for a 135mm diameter rock and the average was transport distance was 9.6 ft. The largest daily mean discharge during this period was 129 ft 3 /s on June 27, 1995 and the largest instantaneous discharge was 202 ft 3 /s.