• The Napa Valley was moist, it naturally stored water for the long summer seasonal drought.

• There were thousands of acres of seasonally wet meadows surrounding pockets of tall tule marsh. The river bed was not much lower than the valley floor, and flood water spread into sloughs and wetlands.

• The river divided and reunited, creating natural islands hundreds of acres in size. Many of the tributaries did not connect directly to the Napa River, but dissipated into valley wetlands,  recharging groundwater. As the rest of the valley dried in the summer months, the wetlands released water to the river, which helped maintain its flow.

• On the well-drained tributary fans, sloping gently between the valley bottom and the adjacent hills, grand valley oaks flourished. Able to reach the seasonally receding groundwater table, these majestic trees dominated the drier parts of the valley.

• Further downstream where the river met the Bay, it spread into a vast area of tidal marshland.

Land use in the Napa Valley has changed dramatically since the 1700s.

Click on the thumbnail image to open a full-size version of the timeline.

Researchers from the San Francisco Estuary Institute are assembling thousands of pieces of evidence about how the Napa River and Valley functioned prior to extensive Euro-american modification. This information will help us understand how the local landscape has changed through time and help develop strategies to improve its health into the future.

Click on the thumbnail image to open a full size version of the map.

The Napa Valley Historical Ecology Study is an investigation carried out by the Friends of the Napa River, the Napa County Resource Conservation District, and SFEI to look into the historical Napa Valley landscape. This research provides baseline information about local landscape conditions and potential future restoration scenarios on the valley floor.

This collaborative effort culminated in the richly illustrated Napa Historical Ecology Atlas, published by UC Press in 2012.