BOARD01130

• Board Meeting Date: 1/26/2000
• Description: ISF Section - Instream Flow Appropriations - Water Division 5
• Board Meetings - Doc Type: Memo

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Table 1: Data

Party Date 0 250%-40% Summer e3/3) Winter (2/3)
BLM 7/9/98 0.32 0.8 - 0.1 2. <)DT 0.7

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 1.7 and 0.4 cfs summer flow and a 0.3 cfs winter flow based on their
July 9th, 1998, data collection effort and water availability analysis. CWCB staff has reviewed
the data collected by the BLM. The summer flow recommendation, which meets 3 of 3 criteria
but falls outside the accuracy range of the R2CROSS model, is 2.9 cfs. CWCB staff believes that
summer flow recommendations that fall outside of the accuracy of the model above 250% of the
measured discharge may overestimate the required summer flow. The winter flow
recommendation, which meets 2 of 3 criteria and is within the accuracy of the R2CROSS model,
is 0.7 cfs.

The BLM has indicated that this is a very high priority stream segment to them. However,
because the summer recommendation falls outside of the accuracy range of the R2CROSS
model, staff believes that more data needs to be collected to accurately predict the summer flow
recommendation. In the mean time, staff believes that it would be appropriate for the Board to
file on a year-round flow of 0.7 cfs, the winter flow recommendation, thus giving JQS some
water right protection until additional data can be collected. Staff has consulted with the
Colorado Division of Wildlife and believes 0.7 cfs will be sufficient to protect the natural
environment to a reasonable degree until additional data can be collected.

Hydrologic Data

After receiving the cooperating agencies' biologic flow 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 East Fork Parachute Creek near Anvil Points eID #09092960), which has
a drainage area of 14.5 square miles (see Gage Summary in Appendix C). The period of record
for this gage is 1976 to 1983, the period ofrecord used by staff in their analysis was 1976-1983,
or seven years of record. The estimated drainage area of JQS Gulch upstream of Golden Castle
Gulch is approximately 1.8 square miles. Table 2 below displays the estimated flow of JQS
Gulch at the confluence with Golden Castle Gulch, in terms of a percentage of exceedence. The
blue shading highlights how often the year-round flow recommendation has been available.

Table 2: JOS Gulch at confluence w/Gotden Castle Gutch - Original Flow

Exceedences Januarv Februarv March Amil Mav June Julv Aunust Se"tember October November December
1% 0.17 0,26 0.43 8,11 34.86 29.41 1.84 0.73 0,38 0,34 0.22 0,14
5% 0,16 0,16 0.36 6.02 21,12 8,19 0,98 0,57 0.29 0.23 0.16 0.12
10% 0,12 0.14 0,34 4.59 15,10 4.34 0.79 0.42 0.24 0,19 0,15 0,12
20% 0.09 0.11 0,25 2.23 11,79 2.61 0.57 0,29 0.17 0.15 0.14 0.11
50% 0.08 0.09 0,12 0.73 4.90 0.91 0.32 0.19 0.12 0.12 0,11 0.08
80% 0,05 0,06 0.10 0,24 0.37 0.17 0,12 0.06 0,04 0.09 0,08 0,06
90% 0,05 0.05 0,09 0,14 0.16 0,08 0,03 0.04 0,03 0.05 0,06 0.05
95% 0.05 0,05 0.07 0.11 0,12 0.04 0.02 0.01 0.03 0,04 0.05 0,05
99% 0,04 0,04 0.06 0.10 0.11 0.04 0.Q1 0.01 0.02 0,04 0.05 0.05

Table 2 shows that the summer and winter recommendation of 0.7 cfs is available 50% of the
time for the months of April though June, 10% of the time in July and 1 % of the time in August.
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 flow of 0.7 cfs was reduced further. Staff recommends that