project was undermanned, thermal records were kept only on the upper 

 Sacramento River and on a few tributary streams, in the Control Valley 

 itself. Other studies were conducted on Trinity River (Hoffett and 

 Smith, 1949), incidental to e fishery investigation relating to a plan 

 to divert water from that coastal drainage into the Sacramento system. 

 A postwar expansion of the temperature studies began in 1946, when new 

 stations were put into operation and new interests developed. Twelve 

 thermograph stations were operating by the end of 1946, as well as 

 several hand thermometer stations, and in 1947 additional localities 

 were brought under investigation. The California Division of Fish and 

 Game also expanded its temperature studies in 1946. They operated several 

 thermographs in the middle and southern Central Valley. The U. S. Bureau 

 of Reclamation and the Division of Water and Sewers, City of Sacramento, 

 have maintained their interest in the collection of thermal data, and these 

 agencies have rendered this report more useful by providing records for 

 inclusion. 



METHODS AND ECUIPMFNT 



Recording thermographs were used to register temperature readings 

 in the cases of most stations treated here. In some instances, hand 

 thermometer readings taken twice daily over long periods are included 

 because they represent the only reoords from that particular station. 

 Thermographs were calibrated once each week. 



Data transcribed from thermograph sheets have been interpreted 

 only to the nearest degree, Fahrenheit. This degree of accuraoy has 

 been selected as most practical on the basis of precision of the thermo- 

 graphs, the width of the stylus line in relation to the spaces on the 

 thermograph chart, the number of people transcribing data, and the 

 statistical significance of more refined interpretation. 



Daily maximum and minimum temperatures are presented for those stations 

 served by thermographs, and monthly mean values are given at the base of 

 each column. When hand thermometer readings are presented in the tables, 

 the hour at which temperatures were taken is indicated. 



SCOPE 



The territory treated here is, with only one exception, within 

 the confines of the Central Valley of California. The exception is 

 the Trinity River at Lewiston and Junction City, and is included 

 beoause of the completeness of the records and the fact that Trinity 

 River water may yet be diverted to the Sacramento drainage. The northern- 

 most valley records are from the discharge through Shasta Dam. Several 

 stations downstream to the mouth of Sacramento River are included, as well 

 as those on various important tributaries. Stations in the San Joaquin 



