9473

• UCREFRP Catalog Number: 9473
• Author: Anderson, R. and G. Stewart.
• Title: Riverine Fish Flows Investigations.
• USFW Year: 2001.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

Instream flow techniques require integration of two processes that combine detailed

knowledge of habitat requirements (by species and life stage), and the availability of

necessary habitats. Both the collection and analysis of these data bases have been very labor

intensive. Recent advances in surveying technique (e.g. G.P.S.) and computer capabilities

(G.I.S.) allow for collection and processing of much larger databases. Also, two-dimensional

(2-D) flow models may have potential for application in instream flow studies (Leclerc et al.,.. .

1995; Bovee, 1996). In theory, 2-D models offer a significant improvement over one-

dimensional (I-D) modeling by increasing spatial resolution, allowing for highly accurate

quantification of physical habitat availability. A spatially explicit flow model may eliminate

the need for microhabitat suitability curves used by IFIM, and also improve biological

resolution of the method. Presently, however 2d modeling is not widely used for fishery

applications and is still an unknown commodity as far as its practicality for instream flow

assessment.

The original intent of this study is to develop and validate a methodology for

determining instream flow recommendations for warm water fish communities in Colorado

(Anderson 1999). This is to be accomplished by determining relationships between habitat

availability and flow using a 2-D flow model to simulate meso-habitat diversity and

abundance over a range of low flows on several sections of three different rivers. Also fish

population and species' life history data will be collected within each of the study sites to

provide habitat use and preference data to determine relationships between base flows and

habitat availability for native fish species of warm water riverine fish communities.

A new study goal was added in 1999 to submit instream flow recommendations for the

Yampa River and Colorado River in the IS-Mile Reach to the Colorado Water Conservation

Board (CWCB), with biological justifications for water right filings in those rivers, by August

2002. The CWCB withdrew water rights filings made in 1995 for these rivers. The 1995

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