7152

• UCREFRP Catalog Number: 7152
• Author: Holden, P. B.
• Title: Relationship between Flows in the Yampa River and Success of Rare Fish Populations in the Green River System.
• USFW Year: 1980.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

34

The information presented herein raises the question--was tem-
perature also the primary factor in 1977? Table 5 shows the mean
monthly temperature at Jensen for 1975-1979. These data show that
temperatures in 1977 were intermediate between years of successful
squawfish reproduction, as 1975 and 1976 were generally cooler than
1977, and 1978 and 1979 were generally warmer, except for June when
1977 was warmest. Another way to look at temperatures is the number
of days above a certain level, during a given period of time. This
approach reflects the daily temperature. rather than the monthly mean.
Table 6 shows the number of days the river temperature was at or
above 600 F or 150 C by June 30 at Jensen for 1962-1966 and 1975-1979.
The values of 600 F and l5Q C are used because the U.S.G.S. recorded
temperatures in of until 1968, when they switched to oC. The data in
Table 6 show that 1965 had considerably fewer days above 600 F than
any other year from 1962-1966. Temperatures in 1977, however, were
intermediate in terms of 150 C days. The conclusion from this data is
that temperature was not a factor causing poor success in 1977.
The discussion of temperatures in 1977 raises the point of the
relationship between flow and temperature. Obviously, temperature is
dependent on ambient weather conditions. which warm the water. and flow
or water quantity. The greater the volume of water. the lower the
warming potential of a given set of weather conditions. Since closure
of Flaming Gorge Dam. temperatures have been colder at Jensen because
of the cold releases from the dam. Yampa River temperatures have been
natural and therefore vary with ambient conditions, as well as flow