ISFAPPC02843

• Case Number: 00CW0104
• Stream Name: Fourmile Creek
• Watershed: Fourmile Creek
• Water Division: 2
• Water District: 12
• County: Fremont
• Instream Flow App - Doc Type: Supplemental Data

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Table 1: Data

Party Date Q 250%-40% Summer (3/3) Winter (2/3)
WWE/QR 11117/98 3.99 10.0 - 1.6 9.1 1.4(1)

www = WW Wheeler QR = Queen of the River
(I) Predicted flow outside of the accuracy range of Manning's Equation.

? = Criteria never met in R2CROSS Staging Table.

Biologic Flow Recommendations
The BLM recommended a 13.0 cfs summer flow and a 4.5 cfs winter flow based on their April
17th, 1996, data collection effort. An alternative flow recommendation was proposed by the City
of Cripple Creek and Cripple Creek/Victor Mining Company based on additional data collected
by WWW/QR, of 6.0 cfs, April 1 through July 31 and 4.25 cfs, August 1 - March 31. The
WWW/QR flow recommendations were based on an adjustment of the CWCB/CDOW 1 ft/sec
velocity criteria standard for summer flows down to 0.8 ft/sec (See WWW/QR Executive
Summary). The CWCB tabled action on this flow recommendation until CWCB staff could
review the additional data collected by WWE/QR and to collect additional data, if necessary.

Staff reviewed the data collected by WWE/QR. The summer flow recommendation, which met
3 of 3 criteria and was within the accuracy range of the R2CROSS model, was 9.1 cfs (See Table
1). The winter flow recommendation, which met 2 of 3 criteria but was outside of the accuracy
range of the R2CROSS model, was 1.4 cfs (See Table 1). It is the belief of CWCB staff that
winter recommendations that fall outside of the accuracy of the model, below 40% of the
measured discharge, may underestimate the required winter flow. To determine the winter flow
recommendations, staff looked at valid winter flow recommendations for the stream segments
above Trail Gulch (4.5 cfs) and below Felch Creek (5.0 cfs) and considered the winter
recommendations offered by the BLM (4.5 cfs) and WWE (4.25 cfs). After consulting with the
Colorado Division of Wildlife staff believes 4.75 cfs will be sufficient to protect the natural
environment to a reasonable degree.

Hydrologic Data

After receiving the cooperating agencies' biologic recommendation, the CWCB staff conducted
an evaluation of the stream hydrology to determine if water was physically available for an
instream flow appropriation. The hydro graph was derived from data collected by the USGS
stream gage for Fourmile Creek below Cripple Creek (10 #07096250), which has a drainage area
of 272 square miles (see Gage Summary in Appendix C). The period of record for this gage is
1992 to present, the period of record used by staff in their analysis was 1992 - 1997, or five years
of record. To estimate the flow of Fourmile Creek at Trail Gulch, staff used the measured flow
at the USGS gage and added the estimated inflow from the Carlton Tunnel, approximately 2.8
cfs, to all values (I). Table 2 below displays the estimated flow of Fourmile Creek at the
confluence with Trail Gulch, in terms of a percentage of exceedence. The orange shading
highlights how often the summer flow has been available and the blue shading highlights how
often the winter flow has been available.

(/) According to WW Wheeler, Engineers for Cripple Creek and Victor Gold Mine, the Carlton Tunnel is currently
flowing at rates of 2.8 cfs to 3.5 cfs