BOARD00820

• Board Meeting Date: 7/26/2006
• Description: ISF Section - Pine River Proposed Water Donation - La Plata County
• Board Meetings - Doc Type: Memo

.

Potential Benefits of Donation:

I
.

Historic Use:

.

power generation uses. During the summer, average monthly
streamflow downstream from the reservoir ranges between 500 -
1,000 cfs as senior water is passed through the reservoir and
water is released to meet contract obligations. During the winter,
average monthly flows range between 52 - 300 cfs (see Appendix
4).

1) Except during a shortage or other conditions specified in
Section 3 of the agreement, PRID and Ihe Tribe have agreed to
guarantee a flow of 136 cfs through the instream flow reach during
the summer months.
2) During the winter months, the amount of donated water is
determined by distinct hydrologic scenarios tied to winter storage
levels in Vallecito Reservoir. During drier years, the amount of
donated water may be reduced, but in no event will the donated
amount be reduced below 5 cfs.
3) The proposed agreement allows additional water to be
donaled to improve the natural environment to a reasonable
degree, and also allows the Board to purchase or lease water (if
physically or legally available) to preserve or improve the natural
environment.
4) Unlike a new instream flow appropriation, water donated
pursuant to this agreement is not subject to undecreed uses or
exchanges of water in existence at the time of the Board's
appropriation.
5) The proposed donation will allow PRID and the Tribe
flexibility to meet their goal of providing a full supply of water to
their respective water users.

Vallecito Reservoir currently provides a supplemental supply of
water to decreed diversions downstream from the reservoir. The
diversions range in amount from less than 10 cfs to approximately
300 cfs. Vallecito Reservoir also delivers domestic and/or
exchange water 10 Ihe Towns of Bayfl8ld and Ignacio, the Tribe,
and over 200 wells, ponds and other uses. During the winter
months, PRID and the Tribe have voluntarily made winter releases
to the Pine River, which have been charged as water which could
have been stored as part of the fill calculation. During the drought
of 2002, there was insufficient storage in Vallecito to fully meet
contract obligations, and PRIO 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 davs
> 49 cfs 53
34 - 49 cfs 27
<34 cfs 20

3