9457

• UCREFRP Catalog Number: 9457
• Author: Ptacek, J. A., D. E. Rees and W. J. Miller.
• Title: A Study of the Ecological Processes on the Fryingpan and Roaring Fork Rivers Related to Operation of Ruedi Reservoir.
• USFW Year: 2003.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

In addition to the field data collected, PHABSIM requires the input of reach slope and
habitat weighting factors. Slope was calculated for each reach using the water surface
elevations and distance from the most upstream transect to the most downstream transect.
Selected sites rarely contain individual habitat types in the same proportion as the reach
total (Morhardt et al. 1983). Therefore, reach length and habitat weighting factors were
determined using the "habitat typing" technique, which is the preferred technique (Bovee
1989). The habitat mapping protocol is described later in this section.
Each site was calibrated to measured water surface elevations and velocity distributions.
Water surface elevations and velocities were modeled for simulated flows using the
calibration corrections. Specific flows simulated varied a little by site but ranged from
1.13 m3/s (40 ft3/s) to 22.63 m3/s (800 ft3/s) for the Fryingpan River sites and from 4.25
m3/s (150 ft3/s) to 24.8 m3/s (876 ft3/s) on the Roaring Fork River. The computer
programs Avparm and Avdepth (submodels of PHABSIM) were run to determine wetted
perimeter, average depth and average velocity for each cross section at each simulated
flow.
Using the PHABSIM submodel HABTAE, habitat suitability curves were run to
determine weighted usable area (WUA) for rainbow trout and brown trout spawning, fry,
juveniles and adults. Weighted usable area values are reported as meter2 per kilometer of
river to allow direct comparison between modeled sites. Adult and juvenile habitat
suitability curves were developed by CDOW and USGS on the South Platte River below
Cheesman Dam, near Deckers, Colorado. These curves are for active fish and do not
adequately represent refuge habitat suitability. The South Platte River in this area is a
tailwater stream with a large salmonid population composed of naturally reproducing
brown and rainbow trout. The spawning curve was developed from brown trout
spawning surveys conducted on Colorado streams (Chadwick & Associates, Inc 1987).
Several analysis techniques were used to interpret the PHABSIM output. Habitat time
series (Bovee 1982), WUA versus discharge (Bovee 1982), and wetted perimeter
Draft Final Report, Fryingpan and Roaring Fork Rivers February 12, 2003
Miller Ecological Consultants, Inc. Page 16