1-02CW373 Supplemental Data

• Case Number: 02CW0373
• Stream Name: South Fork South Platte River
• Watershed: South Platte
• Water Division: 1
• Water District: 23
• County: Park
• Instream Flow App - Doc Type: Supplemental Data

Table 4. Hydraulic parameters for riffle transect (T4).
Flow Calculated Wetted Percent Wetted Wetted Wetted Average Average
(cfs) WSL Perimeter ft Perimeter Area ft2 Width ft De•th ft Velocit ft/s
2
41
96.97
97.09
6 97.17
8 97.25
10 97.31
12 97.36
12.99 97.38
14 97.40
162 97.44
18 97.48
20 97.52
25 97.60
30 97.67
35 97.74
40 97.80
45 97.86
50 97.92
60 98.02
70 98.11
80 98.20
90 98.28
100 98.36
13.54
17.05
17.57
18.01
24.49
25.01
25.17
25.23
25.47
25.71
25.93
26.42
26.86
27.26
27.64
27.99
28.32
28.94
29.51
30.04
30.53
31.00
47.8%
60.2%
62.1%
63.6%
86.5%
88.4%
88.9%
89.2%
90.0%
90.8%
91.6%
93.4%
94.9%
96.3%
97.7%
98.9%
100.1%
102.3%
104.3%
106.1%
107.9%
109.5%
2.98
4.88
6.33
7.58
8.82
10.07
10.65
11.20
12.20
13.21
14.12
16.19
18.12
19.85
21.52
23.09
24.57
27.37
29.98
32.45
34.80
37.02
13.43
16.89
17.38
17.80
24.25
24.74
24.88
24.92
25.09
25.26
25.41
25.74
26.05
26.33
26.59
26.83
27.06
27.49
27.88
28.25
28.59
28.91
0.22
0.29
0.36
0.43
0.36
0.41
0.43
0.45
0.49
0.52
0.56
0.63
0.70
0.75
0.81
0.86
0.91
1.00
1.08
1.15
1.22
1.28
0.54
0.67
0.84
0.98
0.79
0.91
0.93
0.94
1.03
1.11
1.18
1.34
1.48
1.61
1.72
1.83
1.92
2.11
2.27
2.42
2.56
2.69
Water Availability
The available hydrological data was statistically analyzed to estimate the water availability from
October through March. The R- squared value for the best fit regression line was 0.9521. The
observed data from April through September for the 12 year period of record exhibits consistent
longitudinal trends, especially for the fall and spring baseflow periods (Figure 15). This
consistency of the baseflow periods further strengthens the statistical estimation of the winter
flows. Combining the observed data with the estimated discharge data creates a typical
mountain stream hydrograph with peak runoff occurring on average during early June and the
lowest flows occurring during late January to February. Average peak flows for the period from
1989 -2000 averaged 142 cfs and the lowest flows were around 8 cfs. Adequate water should be
available to meet the minimum summer and winter stream flow requirements at transect 4, 16
and 4 cfs, respectively (Figure 16). Transect 2 lies in the area where habitat improvements will
be constructed, therefore, the minimum flow requirements will change with the improvement.
The stream channel is expected to narrow at this location. The average riffle width is
approximately 20 ft. for this reach (Table 2).
Minimum Flow Study, South Fork of the South Platte River - Final Report Page 21
February 19, 2001