pickleweed, eelgrass and giant bulrush (Scirpus californiens). There has also been historically significant fish, mammal, amphibian and avafauna. The marsh is a significant element within the Pacific Flyway providing resting and feeding areas for migratory birds. As of 2006 this ecosystem has been significantly compromised by fill, levee formation, dredging and other development; estimates generally state that 75 percent of the original biological productivity of the marsh has been destroyed. However, it remains a significant habitat and is subject to meaningful wetland restoration activity, that is being actively evaluated as of the 2000–2006 timeframe. Recent developments Because of the recognition of impacts of land development and land use practices, which began in the mid-19th century and have continued until 2006, certain actions are being considered by the Board of Supervisors of Sonoma County. Most notably a special parcel tax may be submitted to voters to assess landowners adjacent to Sonoma Creek. These funds could be used in flood control, hydrology modeling studies, stream conservation work, including erosion control and wildlife conservation. Other current activities include considerable research in public and private sectors including work by the U.S. Army Corps of Engineers, Sonoma County and various private conservation groups. Due to overpopulation of Sonoma Valley as well as overly intensive agriculture, groundwater supplies have been drawn down to the point of causing deleterious effects. The U.S. Geological Survey has found in the Carneros region between Sonoma Creek and the Napa Ridge that due to excessive groundwater drawdown, saltwater intrusion is already occurring, rendering water unsuitable for many uses. See also California slender salamander List of rivers in California List of watercourses in the San Francisco Bay Area Arnold Drive Bridge References Footnotes Sources Lower Sonoma Creek Flood Management and Ecosystem Enhancement Study, Sonoma Resource Conservation District, 2012 Sonoma Creek Watershed Management Plan, Sonoma Resource Conservation District 2013 External links Napa Sonoma Marsh Restoration Project Sugarloaf Ridge State Park Sonoma Creek at Fish Friendly Farming Tidal Variations at Mouth of Sonoma Creek real-time measurements Rivers of the San Francisco Bay Area Tributaries of San Pablo Bay Rivers of Napa County, California Rivers of Sonoma County, California Sonoma Mountains Sonoma Valley St. Helena, California Rivers of Northern California