WSPC03077

• File Number: 8062
• Description: Federal Water Rights - Colorado Litigation - National Forest ISF Claims - Division 2
• State: CO
• Basin: Statewide
• Date: 1/1/1996
• Author: CWCB
• Title: Materials of Interest - Development of Instream Flow Recommendations in Colorado Using R2CROSS - CWCB
• Water Supply Pro - Doc Type: Report/Study

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001941

Appropriating and Protecting an Instream
Flow Water Right
On November 10, 1993, the CWCB
adopted the "Statement of Basis and Purpose
and Rules and Regulations Concerning the
Colorado Instream Flow and Natural Lake
Level Program," These Rules and Regulations
codified existing CWCB procedures for
implementing the Instream Flow Program and
established procedures for handling acquisition
of water, water rights, and interests in water
including conditional rights, modification of
instream flows, and inundation of instream flow
water rights. The CWCB's procedural
requirements for appropriating and protecting
instream flow water rights are also described in
great detail within these Rilles and Regulations.
The procedural aspects of appropriating
and protecting an instream flow water right are
beyond the intended scope of this manuscript.
Individuals who are interested in learning more
about these procedures are encouraged to obtain
a copy of the above-referenced Rules and
Regulations from the CWCB,

Summary
In 1973, the Colorado State Legislature
vested the CWCB with the authority to
appropriate instream flow water rights to
preserve the natural environment to a
reasonable degree, Since that time, the CWCB
has completed instream flow appropriations on
approximately 7,982 miles of Colorado streams,
and the Instream Flow Program is expanding,
The CWCB has adopted standardized
field and office procedures for developing
instream flow recommendations, This
standardization helps to ensure that each
instream flow recommendation is "necessary"
and "reasonable", as required by state statute.
R2CROSS is one of the standard
methodologies employed by the CWCB to
model instream hydraulic parameters, The

CWCB has chosen to use the R2CROSS
methodology because it is both time and labor
efficient, requiring data from only a single
stream transect. It has also been found to
produce sirnilar results to more data intensive
techniques like the IFIM, The R2CROSS
macro is also easy to use and requires very little
in the way of computer hardware or software.
Biologic instream flow
recommendations based upon output from
R2CROSS are designed to maintain xv' xd' and
% WP at critical levels across riffle habitat-
types, It is assumed that by maintaining these
critical hydraulic parameters across riffles,
aquatic habitat in p09ls and runs is also
preserved, In addition to biologic
considerations, water must be physically
available for the CWCB to file for an instream
flow water right.
An instream flow water right requires a
coordinated effort between various state and
federal agencies, the public, and the CWCB,
The culmination of these efforts is a decreed
instream flow water right that is held by the
CWCB on behalf of the people of Colorado to
"preserve the natural environment tC' a
reasonable degree."
The Colorado State Legislature enacted
SB 97 in 1973, By "recognizing the need to
correlate the activities of mankind with some
reasonable preservation of the natural
environment" (~ 37-92-102(3), C,R.S, (1990)),
the Legislature sought to balance traditional
water development with some reasonable
protection of Colorado's natural environment.
This is not a simple task in the semi-arid
Western United States where water is a scarce,
and extremely valuable resource. The ongoing
success of Colorado's Instream Flow Program
assures that coordination between water
development and protection of the natural
environment will continue -- both now and into
the future.

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