33 



HYDROGRAPHIC SECTION 



B\ C. E. Grunsky 



CHAPTER III 



GEOGRAPHY AND HYDROGRAPHY 



OF SAN FRANCISCO BAY 



GEOGRAPHY OF THE BAY AND ITS TRHiUTARY REGION 



The waters of the San Francisco Bay system are made up of three more or less 

 distinct areas, as shown by the frontispiece map, known as San Francisco Bay, San 

 Pablo Bay and Suisun Bay. While the name "San Francisco Bay" is technically 

 applicable only to the larger and more important southern arm of the body of water 

 which has its connection with the Pacific Ocean through the Golden Gate, that name 

 is more often used than any other when it is desired to indicate the entire body of 

 water. This total bay area has its longer dimension closely parallel to the sea coast. 

 It is 52 statute miles in its greatest length in a single direction, and has a maximum 

 width of slightly under 12 miles. The outlet through the Golden Gate is at a point 

 about three-fifths of the total length of the bay from south to north. At a point about 

 one-half of the remaining distance north from the Golden Gate the width of the bay 

 is reduced to a little over one mile, and that point marks the division between San 

 Francisco Bay proper and the upper area known as San Pablo Bay. 



At the eastern end of San Pablo Bay there enters a channel known as Carquinez 

 Strait, through which the combined flow of the Sacramento and San Joaquin Rivers 

 is discharged into San Pablo Bay from .Suisun Bay. The Carquinez Strait is from 

 seven to eight miles in length. Suisun Bay is a large area of water bordered by many 

 tidal flats and salt marshes. At the head of Suisun Bay is the junction of the Sacra- 

 mento and San Joaquin Ri\ers. Above that junction both rivers meander in con- 

 stantly dividing and re-uniting channels, through an extensive delta region of islands, 

 sloughs and marshes. 



The water surface of these bays is not delimitable with perfect accuracy. It 

 will suffice to say that, at ordinary high tide (not including tide marsh lands), it has 

 an area of about 460 square miles. This area is made up of the main San Francisco Bay, 

 288 square miles; San Pablo Bay, 112 square miles (see University of California 

 Publications, Vol. 14, No. 1, p. 20, Albatross Surveys); and Suisun Bay, about 60 

 square miles. 



The Golden Gate, through which the San Francisco Bay is connected with the 

 ocean, is the narrows between Lime Point on the north and P'ort Point on the south. 

 Oceanward from the Golden Gate is the outer bay. This is hemmed in on the north 

 by the cliffs of the Marin shore which end their concave sweep at Point Bonita and 

 on the south by the bluffs of the San Francisco shore which h'dxe their westerly 

 termination at Point Lobos. 



Through this outer bay and through the Golden Gate, which is less than a mile 

 in width, there is a tremendous tidal flow, which has cut and holds the gorge near 

 its narrowest point to depths of more than 300 feet. 



Some fi\-e miles beyond the Heads, as Point Lobos and Point Bonita are commonly 

 called, lies the bar. Here is the crescent shaped crest of a great sand-bar, subject to 



