46 



flood gates will be set to let -water pass out of the reservoir. At each ebb flow in San 

 Francisco Bay the water in San Pablo and Suisun Bays will then run out until these 

 lakes are down to their present winter low tide levels. As the tide in San Francisco 

 Bay, thereupon, begins to rise the gates will close automatically. On their down-stream 

 side the tide may rise to an extreme high stage while on their up-stream side the reser- 

 voir is rising under the influence of the river discharge. As this discharge is not great 

 enough to bring the water in the two bays fully up to high tide before the tide in San 

 Francisco Bay begins to ebb again, the reservoir feature of the project will, as stated, 

 lower the flood plane of the bays and of the entire delta region. 



The fresh water in such a reservoir as described will be a\-ailable for domestic and 

 industrial use. It can be made potable by filtration and chlorination, as is done every- 

 where throughout the I'nited States where water from an unpolluted source is not 

 available at a reasonable cost. This would solve the water supply difliculties of the 

 towns on both sides of the bays and along the strait of Carquinez and would result in a 

 tremendous industrial development. 



The barrier itself if located, for example, on a fairly direct line from Richmond 

 toward San Rafael, would be ideally located to support a highway and a railroad 

 bridge, thus connecting the northerly coast counties with the East Bay population 

 center. 



But where there are so many and such \ast benefits there must be some dis- 

 advantages. Of these the first to be noted is the incon\-enience to ships that navigate 

 the upper bays and river waters, which would be delayed somewhat at the barrier 

 where they would have to pass through locks. There is an ordinary rise and fall of 

 tides in San Francisco Bay of about fi^"e feet. The extreme range of tides is 10 feet. 

 At the barrier the water will, according to the stage of the tide, sometimes be higher 

 on its up-stream side, and sometimes on its down-stream side. Or, again, the water 

 elevation on both sides of the barrier may be, though perhaps only momentarily, at 

 the same level. Because the passing of vessels through locks involves a delay, they are 

 an inconvenience to navigation. But this objection holds equally for a barrier at 

 any location and, in this case, as already pointed out, there is an offsetting advantage 

 in better navigation abo^•e the barrier, which will be efTecti\'e over a wider area than 

 in the case of a barrier farther up the Bay. 



It has been suggested that in case of war there must be no obstruction between the 

 main bay of San Francisco and Mare Island. To meet this requirement, if emergency 

 arises, the use of the bays as a fresh water reservoir can be temporarily abandoned. 

 All gates will then be kept wide open for a few hours or e\en for a few days and ships 

 can pass through the lock chambers unobstructed without ha\"ing to wait for any 

 filling or emptying thereof. 



It is to be noted, too, as affecting San Francisco Ba\' that such a barrier would 

 cut off from the area of the bay now affected by the tides one-third or a little more. 

 The volume of the water which goes in and out through the Golden Gate on flood and 

 ebb tides would be correspondingly reduced. There would be less velocity of current, 

 with some benefit to navigation and there might be some effect in the course of time 

 on conditions within the influence of these Golden Gate currents. It may be argued 

 that the reduced flow of water over the bar outside of the entrance to San Francisco 

 Bay will have the effect of raising the crest of the bar. This is highly improbable. It 

 need not be feared. Furthermore an artificial channel across the bar 2000 feet wide 

 and 40 feet deep at lower low tide has just been completed by dredging. This channel 

 will have to be maintained by further dredging whether or not the in-and-out flow of 

 water through the Golden Gate be modified by the proposed barrier. 



