estuarine communities (with the purpose of introducing the 
eastern oyster) became available. Oyster culture in San Fran¬ 
cisco Bay was a major industry, and with it came other mudflat 
organisms. Some were edible, some innocuous, several destruc¬ 
tive (e.g. Teredo , the shipworm). All were aggressive and 
quickly became dominant members of the Bay's fauna. Today, over 
100 species of introduced benthic and intertidal invertebrates 
are found in the Bay as well as fish, plants, and zooplankton. 
One of the most popular introduced species is the striped bass 
which, as will be described by Dr. Whipple later this morning, 
has also become the Bay's "miner canary" in that its recent 
decline may be a warning of a system pushed beyond its natural 
resilience. 
While the marshes were being filled and new species 
introduced, another activity began in the Central Valley and 
southern California which would have an impact on the Bay -- 
irrigated agriculture. The demand for water for the arid south 
brought political and economic pressures for state and Federal 
water projects to redirect water from the Bay to other uses. 
Although water flow varies considerably from year-to-year, the 
loss of freshwater inflows is evident, amounting to 40-60 
percent of the natural flows in recent years (see Rozengurt, 
this proceedings). Much of the diverted water is taken from the 
spring flows, an important period for some spawning fish. 
Furthermore, the water from Sacramento Valley (which receives 7 0 
percent of the state's runoff) must pass through the strategi¬ 
cally located Delta before reaching the pumping facilities at 
Tracy. The Delta is not only an important fish habitat, it also 
affects downstream salinity intrusion, sedimentation, and 
flooding. Yet this "sieve", through which freshwater must pass, 
is itself weakening as increasingly, frequent levee failures 
during floods and winter storms occur. 
The discussion of water needs and natural resource require¬ 
ments is always bound to create an argument among farmers, bio¬ 
logists, and public interest groups. Even the Federal and state 
authorities responsible for separate water storage and convey¬ 
ance facilities had no joint operating agreements until 1986. 
The State Water Quality Control Board issued a policy (referred 
to as Decision 1485) to provide for water flows necessary to pro¬ 
tect the beneficial uses of the Delta; the decision is up for 
renewal in 1988. We can expect a great deal of data, interpre¬ 
tation, and emotion at these hearings given the impact such a 
decision can have on the competing demands for water use for 
economic and natural resource protection purposes. 
The reduction in water quantity has been accompanied by a 
reduction in water quality. Fortunately, San Francisco Bay 
recovered from the anoxic events of the 1950s and 1960s as a 
result of improved wastewater treatment and the movement of 
discharge locations to regions of greater flushing. Yet 
15 
