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• Board Meeting Date: 7/11/2007
• Description: ISF Section - Pine River Water Acquisition
• Board Meetings - Doc Type: Memo

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winter releases to the Pine River, which have been
charged as water that could have been stored as
part of the fill calculation. During the 2002 drought,
there was insufficient storage in Vallecito to fully
meet contract obligations, and PRID and the Tribe
have indicated their intent to adjust operations to
secure a fill when water is legally and physically
available for storage.

In evaluating the proposed water donation, staff considered the following historical hydrology for
Vallecito releases which was provided by Pine River Irrigation District:

Winter Month Average Releases 1950-2004

Flow Amount % of winter days
> 49 cfs 53
34 - 49 cfs 27
<34 cfs 20

According to data provided by PRID and the Tribe, there were only 2 years of significant
insufficient irrigation supply (1977 and 2002) during the period of record, and two other years
when late irrigation demands could not be met. In addition, there were 7 years out of 45 years
of record (15%) where Vallecito Reservoir did not fill to a level of 110,000 acre-feet.

U.S. Bureau of Reclamation records of Vallecito Reservoir releases reflect post-drought
reservoir operations.
http://www.usbr.oov/uc/wcao/water/rsvrs/ds/vallecito.html

Vallecito Reservoir - Average Monthly Releases (cfs)

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEPT
2002 303 50 50 46 25 25 48 532 524 70 107 86
2003 62 10 6 6 6 6 6 373 675 593 430 104
2004 69 6 6 6 6 6 113 692 823 676 614 541
2005* 413 224 165 17 486 547 558 1290 947 742 623 528
2006* 87 66 13 31 667

* provisional data

According to information provided by PRID and the Tribe, during the dry year condition (60K
storage), releases of 50 cfs might be expected approximately 60% of the time, and releases of
25 cfs or less might be expected approximately 40% of the time. Except for certain emergency
conditions described in the Agreement, releases would never be less than 5 cfs.

Other water riQhts in proposed reach:

There are numerous water rights in the proposed
instream flow reach, the majority of which are
decreed for irrigation. In addition, there are many
undecreed uses and exchanges of water being
made for stock water, irrigation, augmentation and
other uses. PRID, the Tribe and the State and
Flood Protection' Water Project Planning and Fmance . Stream and Lake Protection
Water Supply Protection. Conservation Planning