9520

• UCREFRP Catalog Number: 9520
• Author: Haines, G. B., D. Irving and T. Modde.
• Title: White River Base Flow Study for Endangered Fishes, Colorado and Utah, 1995-1996.
• USFW Year: 2004.
• USFW - Doc Type: 5D,
• Copyright Material: NO

stream may have had surface areas that varied with discharge, whereas cells in the center of the

channel generally had fixed surface areas.

Flows simulated from the hydraulic model were translated into useable habitat when a cell

met the microhabitat criteria for Colorado pikeminnow (Bovee 1986). The evaluation produced a

weighted useable area (WUA) score for each cell; the cell scores were totaled for each cluster and

extrapolated to strata and to the study reach. WUA was calculated for each simulated discharge.

The WUA was determined for each cell using habitat suitability indices (HSI) for depth

and velocity that rated each cell between 0 (unsuitable habitat) and 1 (completely suitable).

Weighted usable area was calculated for three sets ofHSI. The first set was developed from

depth and velocity data collected from the White River between April and November, presumably

during day light, from a number of studies prior to 1987 and reported by Valdez et al. (1987,

Curve Set 10). The second set was developed from data collected from the Yampa River above

Cross Mountain during nocturnal observations of foraging fish in 1996 and 1997 and reported by

Miller and Modde (1999). And the third set was for daytime resting fish, also developed from

Yampa River data by Miller and Modde (1999). The depth and velocity suitability criteria used

for modeling WUA are given in Appendix 2. A particular cell was assigned a weight by

multiplying the HSI scores for depth and velocity.

Mesohabitat Composition

The areas of pool, rifi1e, run, and eddy habitats were estimated for each stratum at each

experimental flow. RHABSIM was used to calculate the area of each habitat type for each

sample cluster, and the clusters were expanded to make estimates for the strata.

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