minimum temperature range in degrees Fahrenheit, mean salinity at 

 Antioch in parts per one hundred thousand (California Division of 

 Water Resources data 19U8, 19U9), and turbidity in inches, as 

 determined with a four-inch Secchi disc. 



Water temperature studies (Cope, 19^9), considered an important 

 part of this investigation, were carried on at critical locations in the 

 Delta (See Fig. 1) . Recording thermometers were used throughout the 

 course of this work. The field installation of the instruments stressed 

 maximum protection and stability. The thermographs were encased in 

 steel housings firmly secured to structures such as concrete bulkheads, 

 bridge dolphins or anchored barges. Servicing of the thermographs en- 

 tailed weekly changes of the charts and the calibration of the instru- 

 ments against a thermometer of known accuracy. Transcription of the 

 daily maximum and minimum temperatures of water and air were completed 

 on monthly temperature data forms. The temperature readings were read 

 to the nearest degree, Fahrenheit. Additional temperature records were 

 obtained by means of hand thermometers at established fyke-net and tow- 

 net stations. 



Studies of chemical features of the Delta waters included weekly 

 analyses during I9I4.8 for dissolved oxygen, alkalinity, pH, and turbidity 

 in the San Joaquin River at Mossdale, Sacramento River at Isleton, and 

 Old River at Clifton Court. Methods followed were obtained from American 

 Public Health Association (1936). Hydrogen ion concentration was deter- 

 mined colorimetrically using a Hellige Pocket Comparator with Brom-thymol- 

 blue, Phenol Red-D, and Chlor-phenol red against standard color discs. 

 Turbidity of the water at the above locations was determined by means 

 of a turbidity scale and tape (U. S. Geological Survey Model). Occasion- 

 ally it was necessary to use a four-inch Secchi disc to determine tur- 

 bidity at the water chemistry stations. The Secchi disc was regularly 

 used in determining turbidity at the tow-net and fyke-net stations. 



BIOLOGICAL INVESTIGATIONS 



The field operations of this study were conducted with a view 

 toward ascertaining the biology, composition, and abundance of the 

 populations considered to be most vulnerable to the Tracy Pumping 

 Plant and the Delta Cross-Channel. Emphasis Was placed particularly 

 upon immature king salmon, striped bass, and shad, the adults of which 

 comprise among the most valuable fishery resources in the Delta. While 

 these three anadromous species received the most attention, a great deal 

 of information was purposely obtained relative to other species of fish 

 utilizing Delta waters, in order that a complete understanding of the 

 aquatic complex of the area would be gained. In addition to the col- 

 lection of data pertaining to the fish themselves, the program included 

 the gathering of such ecological information on the identity, presence, 

 and numbers of invertebrate fish-food organisms, the importance of these 

 organisms in the diet of juvenile fishes, the thermal patterns in the Delta, 

 the chemical quality of Delta waters, and the hydrodynamics of important 

 Delta channels. 



10 



