1914] Sumner, et al.: Physical Conditions in San Francisco Bay 77 
tlashan and Henshaw, 1912; MeGlashan and Dean, 1912). The total 
run-off of these river systems has been obtained approximately by 
adding the figures for the main rivers and those for the tributaries 
entering below the points where the former observations were made. 
For the Sacramento River basin, we have added together the figures 
for the Sacramento River (near Red Bluff), Stony Creek (near 
Fruto), Feather River (at Oroville), Yuba River (near Smartsville), 
Bear River (at Van Trent), American River (at Fairoaks), Cache 
Creek (at Yolo), and Putah Creek (at Winters). For the San Joaquin 
Basin, we have combined the figures for the San Joaquin River (near 
Friant), Mereed River (near Merced Falls), Tuolumne River (near 
Lagrange), Stanislaus River (at Knights Ferry), Calaveras River (at 
Jenny Lind), Mokelumne River (near Clements), and Cosumnes 
River (at Michigan Bar). 
The minor tributaries are omitted from these calculations as well 
as the surface drainage into all these streams, below the observation 
stations (including that into San Francisco Bay as a whole). On the 
other hand, much of the water from some of them is diverted for 
irrigation. 
In table 20 are recorded the figures for the run-off in acre-feet’? of 
these two river systems during ten years for which complete estimates 
are available. The figures for the first six of these years have been 
computed from the estimates of the State Engineering Department of 
California, those for the last four from the figures of the United States 
Geological Survey. Both sets of data are published in the papers of 
TABLE 20 
DISCHARGE OF SACRAMENTO AND SAN JOAQUIN RIVER SYSTEMS IN ACRE-FEET, 
BasED UPON RECORDS FOR TEN YEARS 
Sacramento San Joaquin Combined 
Year system system flow 
1878-79 26,387,000 7,090,000 33,477,000 
1879-80 32,300,000 12,091,000 44,391,000 
1880-81 32,000,000 9,916,000 41,916,000 
1881-82 25,300,000 8,367,000 33,667,000 
1882-83 17,800,000 6,361,000 24,161,000 
1883-84 29,900,000 18,212,000 43,112,000 
1907-08 15,291,000 4,023,000 19,314,000 
1908-09 33,756,000 11,178,000 44,934,000 
1909-10 20,705,000 8,106,000 28,811,000 
1910-11 27,906,000 14,460,000 42,366,000 
Mean of 10 yrs. 26,134,500 9,480,400 35,614,900 
19 One acre foot = 48,560 cubie feet = 325,850 gallons = 1,233.5 cubic meters 
= 1,233,500 liters. 
