9301

• UCREFRP Catalog Number: 9301
• Author: Wydoski, R. S.
• Title: Green River Fishes and Invertebrates.
• USFW Year: 1967.
• USFW - Doc Type: Logan, UT.
• Copyright Material: NO

•
MATERIALS AND METHODS
Permanent staff gages were installed at the four major stations.:
for water level observations. Records from recording water level
gages maintained by the U. S. Geological Survey at Greendale (0.5 MBD)
and near Jensen (93.4 MBD) were also utilized. Water temperature was
measured with a 12-inch mercury-glass thermometer at all stations and
with 30-day Ryan recording thermometers at Echo Park and Island Park.
Additional temperature records at Greendale (0.5 MBD), Allen Ranch
(26.0 MBD), Jensen (93.4 MBD), and Ouray (166.0 MBD) were obtained
from the U. S. Geological Survey and the Utah Department of Fish and
Game. Turbidities were determined with a Jackson candle turbidimeter.
Dissolved oxygen content of the water was determined by the Thierault
modification of the Winkler method. Total and phenolphthalein alkalini-
ties were determined by procedures outlined in Standard Methods (1960).
Hydrogen-ion concentration was determined with a Wallace and Tiernan
comparator. A Gurley pygmy current meter was used to measure water
velocities 1-inch above the bottom at each sample site. The physical
nature of the substrate at each sample site was recorded according to
a classification scheme similar to one suggested by Lagler (1956). All
above environmental observations accompanied each quantitative sample
taken a£ invertebrates.
Benthic invertebrates on hard substrates were sampled with a wire-
mesh device similar to those described by Hess (1941) and Waters and
• Knapp (1961). Ninety-five and 87 samples were collected in 1964 and 1965