FLOOD02454

• County: Gunnison
• Community: Uncompahgre Valley
• Basin: Gunnison
• Title: Uncompahgre Valley Reclamation Project - Hydropower - Part 2 - AB Lateral Unit Water Supply Study
• Date: 12/1/1988
• Prepared For: Montrose Partners and Ucompahgre Valley Water Users Association
• Floodplain - Doc Type: Project

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The essential changes to the UVRP resulting from development would be
represented in the form of increased diversions through the Tunnel and
slight changes in the source of supply for two of the irrigation demands,
the M&D and the Loutzenhizer Canals (see Section 3.3.3). The diversion
headgates of the Ironstone, East and Garnet systems are located downstream
of the proposed facility. Thus, upstream changes would not impact on their
operations so long as water is delivered to the headgates. Therefore, the
day-to-day operation of these systems is not included in the modeling effort
which is described in later sections of this report.

Historically, the average annual demands (see Table 2.1) have been met
through a combination of sources which include Gunnison River diversions,
natural flows of the Uncompahgre River, and return flows from upstream
irrigation systems. Because of capacity restrictions in the South Canal,
these demands have not always been fulfilled. The Cedar Creek diversion was
instigated to provide capacity for additional flows, but has not always been
able to provide enough water, even when combined with flows in the South
Canal. When this has occurred, diversions into the M&D, Loutzenhizer, and
Selig Canals have been proportionately reduced in order to deliver flows to
the Ironstone, East and Garnet systems.

2.2 Svstem inflows

Water to meet irrigation demands is provided by two sources, including
the Gunnison River, which flanks the east side of the UVRP, and the
Uncompahgre River, which flows through UVRP lands from south to north and
joins the Gunnison near Delta. Water from these rivers, together from
return flows from irrigated croplands and local runoff, form the principal
water supplies for the UVRP. Groundwater sources are not used to meet
irrigation or municipal needs, although small wells do serve a number of
small farmsteads.

2.2.1

Gunnison River

The Gunnison River provides over two-thirds of the water used for
irrigation in the UVRP. It originates in the Rocky Mountains to the east of
the project area and flows generally west, where it joins the Colorado River
near Grand Junction. The drainage area at the Gunnison Tunnel, where flows
are diverted into the study area, is approximately 3,965 square miles.

Runoff in the Gunnison Basin is seasonal, with high flows occurring
during the late spring and early summer as a result of snowmelt. However,
flows in the Gunnison River are regulated by Reclamation's Aspinall Unit, a
project consisting of three large dams upstream of the Tunnel. These dams,
in order moving upstream, include Crystal, Morrow Point and Blue Mesa.
Construction of these facilities was completed in 1976, 1970 and 1966,
respectively.

Flows in the river are monitored by the U.S. Geological Survey (USGS)
at several locations within the Gunnison Basin. For this study, the
pertinent gauge is located at the Gunnison Diversion Dam immediately
downstream from the East.Portal of the Gunnison Tunnel. HiSloric flo~

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