ISFAPPC04246

• Case Number: 00CW0101
• 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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the summer flow recommendation based upon meeting 3 of 3 hydraulic criteria and the winter
flow recommendation based upon 2 of 3 hydraulic criteria.

Table 1: Data

Party Date Q 250%-40% Summer (3/3) Winter (213)
WWW/QR 11118/98 6,07 15.2 - 2.43 4 1.5'"
CWCB 4/15199 4,09 10,2 - 1.64 14,5"1 1.0(1)
CWCBIBLM/DOW 10/14/99 16,7 41.8 - 6.68 7,6 1.6(1)
www70R 11117/98 6,53 16,3 - 2.61 ? 0,6(1)
BLM 4/16/96 9.04 22,6 - 3,61 5.8 2,6"1

BLM = Bureau of Land Management DQW = Division of Wildlife WWW=WWWheeler QR = Queen of the River
(1) Predicted flow outside of the accuracy range of Manning's Equation. ? = Criteria never met in R2CROSS Stagmg Table.

Biologic Flow Recommendations
The BLM recommended a 6.0 cfs summer flow and a 2.5 cfs winter flow based on their April
16th, 1996, data collection effort. An alternative flow recommendation, based on additional data
collected by WWW/QR, of 4.25 cfs, May 1 through July 31 and 3 cfs. August I through April
30, was proposed by the City of Cripple Creek and Cripple Creek/Victor Mining Company. 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 WWW/QR and to collect additional data, if necessary.

Staff reviewed the data collected by the BLM and WWW/QR and decided to collect two
additional data sets, bringing the total number of data sets for review to five. The summer flow
recommendations which met 3 of 3 criteria and are within the accuracy range of the R2CROSS
model fall somewhere between 7.6 and 4.0 cfs (See Table 1), Averaging the three summer flow
recommendations gives a summer recommendation of 5.8 cfs,

The winter flow recommendations, which met 2 of 3 criteria all fall outside of the accuracy range
of the R2CROSS model. It is our belief that recommendations that fall outside of the accuracy
range of the model may underestimate the required winter flow. To determine the winter flow
recommendation, staff looked at valid winter flow recommendations for the stream segment
located above Barnard Creek (1.6 cfs) and located below High Creek (4.1 cfs) and considered the
winter recommendation offered by the BLM (2,5 cfs) and WWW/QR (3,0 cfs), After consulting
with the Colorado Division of Wildlife, staff believes 2.75 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 (ID #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 ofrecord used by staff in their analysis was 1992-1997 or five years
of record. The estimated drainage area of Fourmile Creek upstream and including Barnard
Creek is 192 square miles and the drainage area upstream of High Creek is approximately 208
square miles. Tables 2 and 3 below display the estimated flow of Fourmile Creek at the
confluence with Barnard and High Creeks, in tenus 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,