Summer water temperature conditions in the Eel River system, with reference to trout and salmon

Graduation Date

1977

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, 1977

Committee Chair Name

John W. DeWitt

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Water temperature, Salmon, Humboldt State University -- Theses -- Fisheries, Trout

Abstract

During the past few decades, it has become apparent that there is a summertime water temperature problem that may be limiting the well-being of salmonids in the Eel River system of California. It was the objective of this study to determine, from a water temperature standpoint, the locations and amounts of suitable habitat available to native anadromous and resident salmonids in the main stems of the Eel River system during the summer. Water temperatures were measured with hand thermometers at 179 stations during the summer of 1973. Additionally, temperature data were collected from 30 thermographs. Temperatures measured with hand thermometers and the times at which they were measured were compared with records of near-by thermographs to estimate probable maximum water temperatures at all stations. The main stems of the system were divided and classified into stream sections having similar temperature conditions with respect to suitability of habitat for native salmonids. Stream sections reaching a maximum temperature of 28.0 C or greater for at least 100 continuous minutes were classified as "lethal" (i.e., considered to cause total mortality of exposed salmonids). Stream sections reaching a maximum temperature from 26.5 C up to, but not including, 28.0 C for at least 100 continuous minutes were classified as "marginal" (i.e., considered to cause the mortality of at least some of the exposed salmonids). Stream sections reaching a maximum temperature of less than 26.5 C were classified as "satisfactory" (i.e., not considered to directly cause the mortality of salmonids). Of the total of 444.0 miles of stream surveyed, 196.25 miles (44.2 percent of the total) were classified as lethal; 96.25 miles (21.7 percent of the total) were classified as marginal; and 151.5 miles (34.1 percent of the total) were classified as satisfactory. Observations of the distribution and abundance of salmonids supported the temperature classification system. The major factors influencing stream temperature and the effects of high water temperature on salmonids are discussed. However, it was not possible, nor was it the purpose of this study, to gather enough information on stream area conditions to be able to precisely explain the causes of the observed stream temperature conditions, section by section.

https://scholarworks.calstate.edu/concern/theses/nc580p91m

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