THE SHRINKAGE OF A WATER SURFACE: SAN FRANCISCO BAY THE
SHRINKAGE OF A WATER SURFACE: COPYRIGHT © 2001 Paul R. Baumann
San Francisco Bay, a water body of inspiring beauty and imposing
magnitude, covers an area of over 450 square miles (1,165.5
square kilometers) in size. Outlined by softly shaped hills and
low mountains it extends for approximately 50 miles (80
kilometers) in its north-south length and from 12 miles (19
kilometers) down to one (1.6 kilometers) mile in its east-west
width. It opens to the Pacific Ocean through a spectacular gap
called the Golden Gate. The Bay provides a large and refreshing
open space for the millions of people who live and work in the
crowded urban and suburban landscapes ringing its shores. Figure
1 provides an overview of the Bay region. This Landsat 7
Enhanced Thematic Mapper Plus (ETM+)digital image was recorded
during the late spring period of 1999. It is a true color
composite generated by combining ETM+ spectral bands 3 (visible-
red), 2 (visible-green), and 1 (visible-