Poseidon struck the ground with his trident and a spring sprang up; this gave them a means of trade and water —Athens at its height was a significant sea power, defeating the Persian fleet at the Battle of Salamis— but the water was salty and not very good for drinking. (In an alternate version, Poseidon offered the first horse to the citizens, but horses also are associated with Athena in some myths.)
Athena, however, offered them the first domesticated olive tree. The Athenians (or their king, Cecrops) accepted the olive tree and with it the patronage of Athena, for the olive tree brought wood, oil, and food. (taken from http://en.wikipedia.org/wiki/Athena)
That said, we await for our Athena to come bringing a gift that will allow sustainable growth in San Diego.
Check out the following KPBS report: