The original report From the Sierra to the Sea: Ecological History of the San Francisco Bay-Delta Watershed was a product of a three-year effort to develop a landscape level overview of the natural ecological structure, function and organization of the watershed, and the way it had changed over the course of the 19th and 20th centuries. Technical review and contributions from government and water agencies helped produce a collaborative document that provided information on the historical ecological baseline in order to assist in what was envisioned at the time as the most ambitious restoration effort ever undertaken in the United States. We are proud of the fact that the original document is still used as an objective reference, and has provided a foundation and inspiration for similar but more intensively researched localized efforts by others in the Bay-Delta watershed. This 20th anniversary edition contains a new Afterword describing changes to the estuary and its watershed since the report was originally published in 1998.