Page 1 - QUENCY

geography — bounded as it was by a desert,
a mountain range and the Pacific Ocean —
isolated it from the rest of the continent. This
isolation, coupled with its arid climate, impact-
ed the culture and development of the region
throughout its history.1
Limited rainfall and abundant sunshine define
the climate. What little rainfall the county
receives does not coincide with its need:
almost no rain falls during the hot summer.
The county’s coastal plains receive
an average of just 10 inches of rain
a year, while the mountains receive
an average of 30 inches. Yet the
region seldom sees an average
year. Instead, yearly precipitation
tends to fluctuate greatly from year
to year.2
The county is so arid that its entire
4,207 square miles has just seven
principal rivers, all of which go dry
in the summer. As a result, the
county's residents cannot count on
them for reliable year-round water.
Although the mountains can get
ample rain, their steep slopes and
proximity to the coast make captur-
ing their runoff difficult. In the
1
Part 1: Living with the Region’s Water Supply
Introduction – Managing an Extreme Climate
San Diego County lies in the southwest-
ern corner of the continental United
States and California. Its boundaries
today stretch 70 miles inland from the Pacific
Ocean and extend south from Orange and
Riverside counties to the Mexican border. In
earlier ti mes, the county was larger. It included
all of today’s Imperial County, touching on
the Colorado River. It extended north to
encompass much of today’s Riverside and
San Bernardino counties. The region’s
“Water. It’s about water.”
Wallace Stegner,
when asked about California.
Author and Professor at Stanford University
Precipitation in inches
San Diego Annual Rainfall 1943 - 2012
194319451947194919511953195519571959196119631965196719691971197319751977197919811983198519871989199119931995199719992001200320052007200920112012
25
20
15
10
5
0