1917] Barrows: Shipworm in San Francisco Bay 31 



freight steamer, on attempting to make fast to a wharf about a mile 

 above Vallejo Junction at the entrance of Carquinez Strait, rammed 

 the wharf and carried away a number of piles. A pile pulled up for 

 examination when this damage was repaired showed that the broken 

 timbers had been weakened by the operations of shipworms. At 

 Crockett, less than a mile above this point and well within Carquinez 

 Strait, untreated piles are still in use which are known to have been 

 in place for twenty-eight years. 



Wharf at Oleum. — Damage due to wood-borers was also discovered 

 in a third locality in this same general region when repairs on the 

 wharf of the Union Oil Company at Oleum, less than a mile below 

 Vallejo Junction and directly opposite the long Mare Island dike 

 across the ship channel, revealed operations of wood-borers, the piles 

 of the wharf being corroded by the shipworms for a depth of about 

 one inch. 



It thus appears that at three points located .within two or three 

 miles of each other at the head of San Pablo Bay notable damage was 

 done during 1912 and 1913 by a dwarfed race of shipworms, Teredo 

 diegcnsis Bartseh, in a region in which shipworms had not been 

 known to cause damage previously, and that renewed activity of these 

 borers was observed in the spring of 1916 and in the winter of 1916- 

 1917, in the same region. The fact that the damage reported occurred 

 at the head of San Pablo Bay may be explained probably by the 

 location of most of the untreated marine timbering in this bay near 

 the entrance to Carquinez Strait. 



Physical Conditions in San Pablo Bay 



Very fortunately for our present purpose definite information is 

 available upon the physical conditions of the waters of San Francisco 

 Bay (Sumner et al., 1914). This information includes observations 

 upon the temperature and salinity of San Pablo Bay made during the 

 two years preceding that in which the damage just described took place. 



Discharge of Fresh Water into San Pablo Bay. — Though a number 

 of small streams empty into San Pablo Bay besides the Sacramento 

 and San Joaquin rivers, by far the greater amount of fresh water 

 entering the bay comes from these two large rivers, both of which 

 empty into the bay through Carquinez Strait. The approximate 

 amount of fresh water discharged from the Sacraraento-San Joaquin 



