Upon reaching the San Francisco Bay, Spanish explorers came upon the largest inland network of tidal wetlands and marshes they had ever seen. View these segments to learn

• how Portolá discovered the San Francisco estuary by mistake.
• how the appearance of the San Francisco Bay Area has changed dramatically since its discovery.
• why the San Francisco Bay–Delta region is one of the most productive ecosystems in the western Americas.

Download the Viewing Guide for pre- and post-viewing discussion questions, activities, and additional resources to use with students.

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