D.A. Webster 1972 <p>This map presents generalized information regarding the probable maximum yields of wells in the rocks of the San Francisco Bay region.&nbsp; It is intended to serve the needs of planners and other persons seeking general information on potential yields from water wells.&nbsp; Four ranges in probable yield, based on adequacy of the range in yield for major beneficial uses of water, are given.&nbsp; The ranges are related to the concept of normal probability; that is, well yields are expressed in terms of the 68- and 95-percent levels of chance.&nbsp; For example, there is a 68-percent chance that wells in areas designated A will yield from 0.5 to 5 gpm (gallons per minute) and a 95-percent chance that wells in such areas will yield from 0.1 to 10 gpm. assuming operation without excessive drawdown.&nbsp; Thus, it can be expected that most wells drilled in area A will obtain water supplies marginal to adequate for domestic purposes, that most wells will yield fewer than 10 gpm, and that some wells will be virtually dray.</p> application/pdf 10.3133/mf431 en U.S. Geological Survey Map showing ranges in probable maximum well yield from water-bearing rocks in the San Francisco Bay region, California reports