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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. Rock Creek to Boulder Creek
o 90 cfs (April I - April 30)
o 115 cfs (May I-August 31)
o 90 cfs (September I - September 30)
o 78 cfs (October I - October 31)
o 67 cfs (November I - March 31)
· Boulder Creek to Slate Creek
o 78 cfs(March I - March 31)
o 90 cfs (April I - April 30)
o 125 cfs (May I - August 31)
o 90 cfs (September I - October 31)
o 70 cfs (November 1 - February 29)
. Slate Creek to Green Mountain Reservoir
o 125 cfs (May I - September 30)
o 90 cfs (October 1 - November 30)
o 85 cfs (December I - April 30)

EVALUATION OF PROPOSED ACOmSITION

The proposed acquisition involves the Peabody Ditch which diverts from Boulder Creek at approximately the half-way point
in the Boulder Creek instream flow segment. The water is then carried by the ditch down gradient traversing the drainage
divide between Boulder Creek and the next major tributary, Slate Creek. The water has historically been used to irrigate
lands between Boulder Creek and Slate Creek. The return flows then enter the Blue River either directly or via Slate Creek.
So, the aquatic benefit of leaving the water right in the stream accrues to both Bonlder Creek and the Blne River. Boulder
Creek and the Blue River benefit from the full diversion amount up to the point of historic return flow and then the Blne River
benefits from the calculated consumptive use being in the stream from the return flow point down to the end of the instream
flow segment going into Green Mountain Reservoir.

The water rights being considered for acquisition have an aggregate total decreed flow of8.5 cfs. For the purposes oflhis
evaluation, it is asswoed that the full 8.5 cfs is diverted throughout the irrigation season (June - October). It is also assumed
that approximately 50% of the diversion amount is consumptively used by the irrigated crops. With those simplified
assumptions, Boulder Creek and the upper portion of the Blue River segment (Boulder Creek to Slate Creek) would
experience the benefit of having an additional 8.5 cfs in t1ie stream The Blue River (from a point just upstream o(Slate
Creek down to Green Mountain Reservoir) would realize the benefit of having approximately 4.25 cfs in the stream that
would norothetwise be there. Thus, the lower 50% of the CWCB's Boulder Creek instream flow and most of the CWCB's
Blue River segment between Boulder Creek and Slate Creek would be augmented by up to 8.5 cfs. From a point on the Blue
River slightly upstream of Slate Creek down to Green Mountain Reservoir, the CWCB's instream flow water rights in these
two segments will be angmented by approximately 4.25 .cfs.

Benefits to the Boulder Creek Instream Flow