WSP00452

• File Number: 8200.766
• Description: Gunnison River Basin General Publications - Correspondence - Reports
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 10/27/1992
• Author: Unknown
• Title: Gunnison Basin Models - Planning Model - 1991-1992 - Draft Functional Specification - Gunnison River Basin Planning Model
• Water Supply Pro - Doc Type: Report/Study

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Functional Specification for the Planning Model

except in very low storage conditions), 5) power generation and flood control space
evacuation, 6) augmentation for junior water rights called out by in-basin seniors, 7)
replacement for upper basin users called out by Blue Mesa, and 8) Compact obligations, The
amount of each of these releases will be subject to modification by model users in two ways,
by setting the delivery amounts desired at specific demand points and by setting the total
amount of release permitted for each purpose (including setting amounts to zero).

Explicit power and flood control releases will be made only to the extent that water
rights bypasses and deliveries for the Gunnison Tunnel. Endangered Species, DallaslDolores
mitigation, and the Black Canyon do not achieve desired power production rates or reservoir
drawdowns. All releases will be routed through power outlets if capacity remains therein.
Desired power production rates and reservoir drawdowns will be based on inflow forecasts for
the months of January through July and on declining storage targets in the months of August
through September; the objective of these operations will be to fill the reservoir by the end of
July withouta spill and to draw the reservoir down by the end of December. The storage and
release rules and targets will be subject, within certain limitations, to modification by model
users,

Both the direct-flow right for the Blue Mesa powerplant and the storage rights for Blue
Mesa Reservoir will be represented in the model, though the direct-flow right will be
represented indirectly, Accruals to storage in Blue Mesa will occur only when the Blue Mesa
storage decree is in priority and will be subject to two conditions, First, in order to simulate
the effect of the direct-flow power decree for the Aspinall Unit, storable inflows to Blue Mesa
will be debited against the fill limit for the year only to the extent that they exceed the lesser of
2,500 cfs or the flow through the Blue Mesa powerplant, Second, some Blue Mesa fill will be
allowed to accrue in Taylor Park Reservoir as out-of-priority storage under the UGRWCD
refill decree, If Blue Mesa subsequently fills, the out-of-priority storage will be "booked over"
to the refill decree. .

Uncompahgre Project and Taylor Park Reservoir

The features of the Uncompahgre Project that will be explicitly represented in the
Planning Model include Taylor Park Reservoir, the Gunnison Tunnel, the South Canal, the
West Canal, the M&D Canal, the Loutsenhiser Canal, the Selig Canal, the Ironstone Canal, the
East Canal, and the Garnet Canal. The entire storage capacity of Taylor Park will be
represented in the model as will the hydraulic capacities of the service outlet and spillway.
The Gunnison Tunnel and the canals and laterals in the Uncompahgre Valley will be
represented at their current hydraulic capacities.

Taylor Park Reservoir

Taylor Park Reservoir will be assumed to make releases for the following purposes: I)
Uncompahgre Valley Project deliveries to Blue Mesa (Taylor Park Exchange account) or the
Gunnison Tunnel from water stored under the UVWU A senior decree, 2) contract deliveries to
users above Blue Mesa from storage under the UGRWCD ref1l1 decree, 3) fishery enhancement
from storage under the refill decree, 4) flood control space evacuation, and 5) augmentation
and/or replacement for users above Blue Mesa from the refill decree. The amounts of releases
for project and contract deliveries and for fishery enhancement will be based on user-supplied
targets and limited by overall user-supplied storage allocations for each type of release.
Additional constraints on water available for various types of releases will be imposed by the
annual amounts of water stored under the two decrees for the reservoir.

Flood control releases will be made only if other types of releases do not achieve desired
levels of storage in the reservoir and will be based on inflow forecasts for the months of March
through May and on storage targets in remaining months. These operating rules and targets

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