New Study Paints Picture of Pre-Development Delta

A new historical ecology study of the Delta provides a detailed look at the estuary and how it functioned before levees and water diversions began transforming it 150 years ago.

Using old maps, early photographs and the accounts of explorers, settlers and hunters from more than a century ago, the richly-illustrated study gives a never-before-seen picture of the ecosystem at the heart of California’s environmental and water debates.

The report, “Sacramento-San Joaquin Delta Historical Ecology Investigation: Exploring Pattern and Process,”was developed by researchers in historical ecology at the San Francisco Estuary Institute-Aquatic Science Center, in collaboration with California Department of Fish and Game and with input from numerous scientists, archivists, historians, and local residents. The project was funded by DFG through the Ecosystem Restoration Program.

“This masterpiece of historical ecology will be widely used by policy makers and scientists because it provides a detailed, painstakingly-crafted description of the Delta of the past – a benchmark from which we will measure the success of programs to rebuild habitats and ecological functions lost over the past century and a half,” Jim Cloern, a senior research scientist at the U.S. Geological Survey in Menlo Park, said in a news release from DFG. Cloern was not part of the research team.

SFEI-ASC Senior Scientist Robin Grossinger said the purpose of the study was “not to go back, but to understand how this landscape worked so we can re-establish ecologically functional and cost-effective habitats within the contemporary landscape.”

The report notes that only 3% of the tidal wetland that existed in the Delta in the early 1800s remains wetland today. It describes the historical Delta as a series of landscapes: the central Delta was characterized by tidal freshwater wetlands of tule (a tall wetland plant) and willow with numerous winding channels; the north Delta featured broad flood basins of tule interspersed with lakes, and rivers bordered by broad forests; while the south Delta had wetlands interspersed with side channels, lakes and ponds, willows and patches of seasonal wetland.

The report and GIS are available for download here. Printed copies of the report, with dozens of rarely seen historical accounts, maps and photographs describing the Delta of the recent past, will also be available for $75. In addition, an interactive map featuring the historical landscape reconstruction and early documents used to create the picture was created by SFEI-ASC with Stanford University and KQED. It can be found here.