WSP11844

• File Number: 8240.200.36
• Description: Black Canyon National Monument
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 1/1/1992
• Author: USDOI/BOR
• Title: Proposed Contract to Deliver Water from the Wayne N. Aspinall Unit to the Black Canyon of the Gunnison National Monument
• Water Supply Pro - Doc Type: Publication

As discussed elsewhere in this packet, the
National Park Service holds a 1933 Federal
reserved water right for the Monument. In
1982, the Colorado Water Court upheld the
validity of this right, and ordered the United
States, through the National Park Service, to
quantify and perfect the right.

The Colorado Water Conservation Board
(CWCB) holds many "instream flow" rights in
the Gunnison Basin; these are rights
established to maintain water within certain
reaches of streams, Recently, the CWCB
accepted a donation from the Nature
Conservancy of a conditional water right for
conversion to a 300 cfs in stream flow. This
right is for the reach between the streamflow
gage below the Gunnison Tunnel and the
confluence with the North Fork of the
Gunnison.

In addition to water rights for direct
diversions, storage rights can be established.
These are rights to store available water in a
reservoir; they allow for release and use of
such water--past senior rights--when needed.
The largest single perfected storage decree on
the Gunnison River is the 952,000 acre-foot
decree for Blue Mesa Reservoir. Other water
storage facilities in addition to those of the
Aspinall Unit include numerous smaller
reservoirs and several larger Reclamation
project reservoirs on Gunnison River
tributaries-- Taylor Park Reservoir on the
Taylor River, Silver Jack Reservoir on
Cimarron Creek, Crawford Reservoir on the
Smith Fork, Paonia Reservoir on the North
Fork, and Ridgway Reservoir on the
Uncompahgre River.

Senior water right holders can place a
"call" on the river--a request to the State
Engineer to force water users with junior
decrees to cease or diminish their diversions
and pass the called amount of water to the
downstream senior water right. The State
Engin~r is the person charged by State law

with the supervISIon and administration of
water and the enforcement of decreed priority
and legislative enactments. The responsibility
for overseeing water rights on the Gunnison
River is delegated to the Division Engineer in
Montrose, Colorado (Division 4). Operation
of the Aspinall Unit has indirectly reduced the
frequency of calls on the river. Since its
construction, releases have exceeded historical
flows in normally low flow months of
summer, fall, and winter, Thus senior water
right holders have had more dependable
supplies and junior water rights have increased
in value.

In 1991, Colorado Water Court decisions
on water rights applications (Arapahoe County
for the Union Park Project) clarified water
rights and water availability questions in the
Gunnison Basin, These decisions, along with
Reclamation's intent to deliver Aspinall Unit
storage water to the Monument and to
endangered fish habitat, is expectea to result
in stricter administration of water rights in the
entire Gunnison Basin.

Developmental Effects on Gunnison River
Flows

Since completion of the Gunnisoll TUllJl",1
in 1911, flows of the Gunnison River below
the tunnel have been reduced due to diversions
for purposes of the Uncompahgre Project.
Construction and operation of storage features
of the Uncompahgre Project (Taylor Park
Reservoir in 1937) and of the Aspinall Unit
have further modified these flows, The
impact of these developments is best reflected
by flow data measured since 1977, following
completion of Crystal Dam as a regulating
reservoir of the Aspinall Unit. This period
includes a representative range of dry, normal
and wet water years. The following graph
and table show how the monthly distribution
of flows has been affected by Taylor Park
Reservoir and Aspinall Unit storage and
operation.

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