WSPC02454

• File Number: 8283.200
• Description: Colorado River Basin-Colorado River Computer Models-Colorado River Decision Support System
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1995
• Title: San Juan River Basin Modeling-San Juan Special Water Right Operations
• Water Supply Pro - Doc Type: Report/Study

0004;3

PINE RIVER PROJECT IVALLECITO RESERVOIR)

The Pine River Project was completed by the U.S. Bureau of Reclamation in the early 1940's
and provides a supplemental irrigation water supply to approximately 48.000 acres (USBR 1994)
of land in the Los Pinos River (aka Pine River) basin in southwestern Colorado and northern New
Mexico. These lands include Indian owned lands on the Southern Ute Reservation and lands
outside of the reservation. The principal feature of the project, Vallecito Reservoir, is operated to
store surplus flows of the Pine River during the spring snowmelt runoff and subsequently release
that water to supplement the late season irrigation demands for a number of downstrE\am direct
flow water rights, including a large priority owned by the Southern Ute Indians. The Project
irrigation water is distributed through a number of privately owned irrigation structures or through
structures under the jurisdiction of the Bureau of Indian Affairs. The Project is managed by the
Pine River Irrigation District.

Vallecito Reservoir (WOlD 313518) is located on the main stem of the Pine River about 18
miles northeast of Durango. The reservoir has a total capacity of 129,700 acre,feet of which
125.400 acre-feet is the active pool. The remaining 4,300 acre,feet is dead storage. The
reservoir surface area at the normal high water line is about 2,720 acres. Vallecito Reservoir has
the following decreed absolute storage right:

ADJUDICATION
DATE

APPROPRIATION
DATE

ADMINISTRATION MO..Nr
NUMBER

NAME

Vallecito Reservoir

03,07-1966

11-13-1935

31362.00000 129,674 AF

There is also a conditional water right for hydroelectric power generation through a
penstock at the base of the dam. This water right was adjudicated in December 1980 for 720 cfs
and has an appropriation date of June 1, 1979.

Monthly records of the historic inflows to Vallecito Reservoir, end,of,month storage
contents and releases from the reservoir were obtained from the USBR through 1993. Under
current operation of the reservoir, the storage releases during the irrigation season are determined
by the Pine River Irrigation District based on the natural flows available for diversion and
anticipation of the following year's runoff. At the end of the irrigation season, the reservoir is
typically drawn down to approximately 77,000 acre-feet to prepare for the spring runoff and to
maintain a winter water surface elevation well below the spillway crest. Forecasts for the
anticipated snowmelt runoff into the reservoir are provided by the National Weather Service on a
twice monthly basis, beginning in January and continuing through July. During January, February
and March, the amount of storage capacity required for flood control is determined using relations
developed by the Corps of Engineers and releases are made as necessary to make the flood control
space available. During the peak runoff period, releases are adjusted to maintain the flow in the
Pine River to a rate less than 2,500 cfs. Peak snowmelt runoff occurs during late Mayor early
June. The reservoir usually reaches it peak storage levels by July 1. The reservoir levels then
decrease as the runoff subsides and irrigation water is released.

During the winter season, the required release is equal to the reservoir inflow. However,
in order to minimize cavitation of the regulating gates, the releases through the outlet works have
been maintained at a minimum of 30 to 50 cfs. In addition, winter releases through the

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