Laguna Watershed Knowledgebase

Back to the Future: Applying the Lessons of History to the Challenges of Climate Change

Sonoma Valley’s freshwater creeks and wetlands were once vastly different than they appear today. Once characterized as a “fountain of fountains,” the valley was known for its abundant creeks, wetlands, and springs. There was noticeably more water here than in neighboring Petaluma or Napa Valleys. Except during floods, many tributaries lacked a surface connection with the mainstem of Sonoma Creek. Instead, they flowed out of the hills and onto their alluvial fans, spread into two or more distributaries, and finally petered out on the flats, their waters slowly sinking into the soil and replenishing the groundwater.

Changes began immediately upon the founding of the Sonoma Mission in 1823, with ditches dug for irrigation, to speed the runoff of floodwater, and to drain wetlands. Connections were created between formerly unconnected creeks and water bodies. Within 50 years, all the main tributaries had been connected to the mainstem, and Sonoma Creek had become a “Freeway to the Bay,” conveying water off the land. This trend has continued right up to the present, with our hydrological network becoming increasingly connected at smaller and smaller scales.

Climate change models predict both more intense storms and drought in the future, with the changes to the Sonoma Valley watershed outlined above only serving to amplify these extremes. Based on a decade of research supporting various efforts by the Sonoma Ecology Center, including the Sediment Source Analysis for the Sonoma Valley Watershed TMDL, this poster will present historical and modern maps, quotes, and other material to document human-caused changes to the valley’s hydrology over the last 200 years, examine how these changes exacerbate the predicted effects of climate change, and highlight ideas for moderating these effects through restoring or mimicking historical patterns.