BOARD00223

• Board Meeting Date: 9/13/2004
• Description: ISF Section - Proposed Water Right Donation - Colorado Water Trust, Peabody #1 Ditch and Lund Enlargement, Boulder Creek and Blue River
• Board Meetings - Doc Type: Memo

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Benefits to the Blue River Instream Flows

The value of the Blue River fishery cannot be understated or overlooked. It is a heavily used, highly accessible public
resource important to local economies and statewide interests. Its productivity as a fishery is well documented by the
Division of Wildlife; it has consistently maintained its Gold Medal status by maintaining both the required biomass and the
reqnired percentage of the population in the quality size class. As stated previously, the Division bas viewed instream flow
issues on streams of this caliber very different from others in that the flows that are reasonable to preserve this type of
environment are different from that of other streams; in other words, the standard of what flows are reasonable was different
in this case.

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As stated above, it is assumed that the proposed acquisition will provide approximately 8.5 cfs to the section of the Blue River
from Boulder Creek to Slate Creek and the approximately 4.25 cfs to the Blue River from Slate Creek to Green Mountain
Reservoir. I have revisited the original R2CROSS and SEIS data to evaluate the effects of these added flows to the Blue
River fishery. The SEIS IFIM/PHABSIM data is particularly useful in this case because it is incremental data - the data lends
itself to comparative and incremental analyses. One ofPHABSIM's better qualities as an instream flow quantification
method is the fact that it gives one the ability to examine relative gains and losses in flow scenario investigations.

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Data provided by CWCB staff indicates that the historic irrigation season in the Boulder Creek basin (based on diversion
records for all Boulder Creek ditches) is June through October. The life stages of interest during this time period are brown
trout adults, spawning adults, fry (emergence and growth), and juveniles and rainbow trout adults, spawning adults, incubating
eggs, hatching eggs, fry (emergence and growth), and juveniles. Adding 8.5 cfs to the existing instream flow appropriations
for June through October (Boulder Creek to Slate Creek), the following increases in habitat will be realized:

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Increased now Months Species and Life Change in Habitat
Stalle (su ft/IOOO ft\
125 cfs to 132.5 cfs Julv - AUlm.t Brown Juveniles 1331
Brown Adults 1106
Brown Combined 2451
Rainbow Soawninll 223
Rainbow Juveniles 321
Rainbow Combined 335
90 cfs to 98.5 cfs September - October Brown Soawning 224
Brown Frv 81
Brown Juveniles 102
Brown Adults 45
Brown Combined 981
Rainbow Juveniles 15
Rainbow Adults 199
Rainbow Combined 202

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For the Blue River from Slate Creek downstream to Green Mountain Reservoir the following improvements will be realized
by adding 4.25 cfs to the existing instream now appropriations for the historic irrigation season:

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Increased now Month. Specie. and Life Cbange in Habitat
Sta!!e Isu flIIOOO ft)
125 cf. to 129.25 Julv - September Brown Juveniles 665
Brown Adults 502
Brown Combined 1220
Rainbow Spawning III
Rainbow Juveniles 160
Rainbow Combined 167
90 cf. to 94.25 cfs October Brown Soawninll 107
Brown Frv 39
Brown Juveniles 51
Brown Adults 24
Brown Combined 466
Rainbow Juveniles 10
Rainbow Adults 102
Rainbow Combined 99

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