This condition will be magnified when the water-use projects 

 under construction, namely the Tracy Pumping Plant and the Delta 

 Cross-Channel j are placed in operation and start drawing Sacramento 

 water to the pumps. In addition to the Sacramento water schedule 

 for Delta-Mendota demands, additional inflow will be required for 

 consumption and salinity control. Based on the ultimate require- 

 ments with the Delta-Mendota pumping plant taking of ii,600 second 

 feet, salinity control of 2,700 and San Joaquin Delta consumption 

 of 2,700, a total of 10,000 second feet of Sacramento water will 

 be transferred into the San Joaquin Delta. Three Mile Slough, 

 connecting lower Sacramento River with San Joaquin River, delivers 

 an additional net tidal flow of 95>0 second feet from the Sacramento 

 to the San Joaquin Delta (California Division of Water Resources, 

 Bulletin No. 27). This varies however, depending on the character 

 of the tide. During the period of seaward migration of Sacramento 

 River salmon, a proportionate number are transferred with the net 

 flow through Three Mile Slough to the San Joaquin Delta. Samples 

 of Sacramento migrants taken in Three Mile Slough and station 16, 

 before migrants from Georgiana Slough had entered the central Delta, 

 indicated the movement of salmon through this slough to the San Joaquin 

 Delta. 



The seasonal movement of juvenile Sacramento River salmon into the 

 San Joaquin Delta and toward the Tracy Pumping Plant can be expected to 

 be proportional to the amount of Sacramento River water transferred for 

 project operation. 



The position of the San Joaquin River salmon migrants with refer- 

 ence to the division of the river flows within the Delta and the Tracy 

 Pumping Plant is extremely important. The initial division of the San 

 Joaquin River into Delta channels occurs at the bifurcation from Middle 

 River, with the major flow down Middle River. According to Bureau of 

 Reclamation determinations of flow ratings of San Joaquin River at 

 Brandt Bridge against the flow at Vernalis (USBR Delta District 

 Hydrography Report, Volume No. II, 19h7) , the proportion of flow into 

 Middle River is about two-thirds to three-fifths of recorded runoff 

 of 2,500 to 5,000 second feet at Vernalis, Further division of flow 

 occurs where Old River separates from Middle River, the major portion 

 flowing down Old River channels, consisting of Salmon Slough, Grant 

 Line and Fabian Bell Canals and Old River. Middle River, at its 

 bifurcation from Old River, takes only a limited quantity of water 

 (less than 100 second feet when the recorded flow at Vernalis is 3000 

 c.f.s.). The Old River channels converge within a half-mile of the ap- 

 proach canal of the Tracy Pumping Plant. 



It has been demonstrated by the present investigation that the 

 downstream migration of San Joaquin salmon through the Delta was prin- 

 cipally via the channels coverging on the Tracy Pumping Plant (Tables 

 5 and 6, Figs 3 and h) . With the project in operation under the present 



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