BOARD01425

• Board Meeting Date: 3/29/1999
• Description: ISF Section - Methodology Report
• Board Meetings - Doc Type: Memo

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Colorado Water ~onservation Board

Department of Natural Resources
1313 Sherman. Street
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]

STATE OF COLORADO

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Bill Owens
Governor

MEMORANDUM

GregE.Walcher
Executive Director, DNR
Peter H. Evans
Director, ewes

To:

Members, CWCB

From:

Dan Merriman
Greg Espegren

Date:

March 22, 1999

Re:

Agenda Item 16, March 29-30,1999, Board Meeting
Instream Flow Program - Methodology Report

Attached, please find a copy of a report entitled "Evaluation of the Standards and Methods Used for
QuantifYing Instream Flows in Colorado". This report was prepared to satisfY one of the Objectives
under Goal 3, "Environmental Conflict Resolution", of the Board's Long Range Plan. Specifically,
the Board's Instream Flow Ouantification objective was to "complete an evaluation of the need for
new standards and methods for quantification of instream flows and natural lake levels..."

The report provides an overview of the instream flow quantification methods currently employed
throughout the United States. It summarizes and evaluates the methods most widely used in the
semi-arid states and includes a discussion of the applicability of those methods within Colorado. The
methods discussed include R2CROSS, the Instream Flow Incremental Methodology and Physical
Habitat Simulation System, Tennant, and Wetted Perimeter.

The report concludes that the Board's existing procedures are consistent with a three-step adaptive
management approach that allows the Board to utilize an accepted methodology, like R2CROSS,
to provide a reasonable degree of protection in a timely manner. This initial degree of protection can
then be monitored to determine whether it is truly providing the desired degree of protection. If not,
Colorado water law and the Board's existing procedures allow the original appropriation to be
enlarged, if additional protection is required, or modified downward if the original appropriation is
found to be excessive.

A draft of the report was distributed to the Board at its November 1998 meeting. At that time, the
Board authorized staff to release the draft report to the public for comments. Notice of the release
(attached) was mailed to everyone on the Board's Instream Flow Subcommittee mailing list.

As of the date of this memorandum, staff has received only the attached written comments from
William Walsh of Walsh Aquatic Consultants, Inc. Mr. Walsh indicates that the objective of both