BOARD02525

• Board Meeting Date: 1/26/2000
• Description: ISF Section - Instream Flow Appropriations - Water Division 2
• Board Meetings - Doc Type: Memo

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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 I: Data

Party Date Q 250%-40% Summer (3/3) Winter (213)
BLM 4/28/97 2,01 5,0 - 0,8 1.8 1.3
CWCB 4/16/99 1.04 2,6 - 0.4 ? 0,3(1)

BLM = Bureau of Land Management
(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 1.8 cfs summer flow and a 1.35 cfs winter flow based on their April
28th, 1997. data collection effort, Staff reviewed the data collected by the BLM and decided to
collect an additional data set, bringing the total number of data sets for review to two, The data
set collected by CWCB staff was not used in the analysis because the 3 of 3 criteria factor was
never met and the winter flow recommendation was outside of the accuracy range of the
R2CROSS model. The summer flow recommendations which met 3 of 3 criteria and are within
the accuracy range of the R2CROSS model is 1.8 cfs (See Table I), The winter flow
recommendations, which met 2 of 3 criteria and are within the accuracy range of the R2CROSS
model is 1.3 cfs

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 Oil Creek is approximately 14 square miles. Table 2
below displays the estimated flow of Oil Creek at the confluence with Fourmile Creek, 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,

Table 2 : 011 Creek at confluence with Founnlle Creek

1%
5%
10%
20%
50%
80%
90%
95%
99%

Januarv Februarv March Aonl Mav June Jut... Au"ust ~tember October November December
1.21 0,80 0,69 -, 3.37 -17,73" ~9;18~ ";"'5.14"- "'3.84'" '. 2;44 ;,:;'...08 '-4,09 .; 1,16
0,93 0.72 0.57 3,09 ' 10.0s'" ;;;::-L7.88 " 4,43 2;37 ~, ~,.1.80.;;' 1,49 1,36 0,98
o,n 0,61 0.51 '_2;42. aoa.!. $/i 8.38 4,09 ~,.._2.03 ~.. 1,39 1,39 0,93 0,68
0.57 0.45 0.49 1,29 6.lJT'..' 4,99 ~.....2..$1_ 1,80 1.24 1,08 0,68 0.57
0,33 0.31 0.41 o,n 1,62 .U7.... 0,68 o,n 0,72 o,n 0,44 0,33
0,26 0.21 0,30 0,50 0.72 0,62 0.62 0.51 0.47 0.47 0,38 0,28
0,23 0,20 0,25 0,46 0,47 0,48 0,50 0,25 0,26 0,35 0,34 0,26
0,21 0.19 0.24 0.42 0,34 0,40 0,39 0,21 0,23 0,28 0,31 0.24
0,16 016 022 0,36 0,27 0,37 0,29 0,14 0.21 0,22 0.28 0,19

Table 2 shows that the winter recommendation of 1.3 cfs (October 15th - April 141h) is not
available December through March and is only available 10% of the time in April. Table 2 also
shows that the summer flow recommendation of 1.8 cfs (ApriI15'h - October 14lh) is available
10% of the time in April and August, 20% of the time in May and July, 50% of the time in June,
5% of the time in September and I % of the time in October. Based on the above water
availability analysis and the requirement of the CWCB staff to balance the needs of mankind
with a reasonable preservation of the natural environment the recommended summer and winter
flows of 1.8 cfs and 1.3 cfs must be reduced further, Staffrecommends that the proposed flow
recommendation be changed to 1.8 cfs (May 15 - June 30). 0,75 cfs (July I - October 14). 0,3