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Audubon Canyon Ranch (ACR) manages a system of wildlife sanctuaries in Marin and Sonoma counties that includes approximately 450 acres of shoreline properties on Tomales Bay. Since the early 1970's, ACR has conducted ongoing programs in nature education, biological research, and local conservation to help ensure the long-term protection of the natural resources of Tomales Bay. Livermore Marsh, the centerpiece of ACR’s Cypress Grove Preserve and Research Center in Marshall, has been the primary location for field seminars about Tomales Bay, and the subject of monitoring efforts to track changes in bird use, vegetation, sediment accretion, and hydrology.
In February 1998, floodwater breached an historic railroad levee at Audubon Canyon Ranch’s Livermore Marsh, reconnecting the coastal freshwater marsh with Tomales Bay. Following considerable study and consultation with hydrologists, biologists, geologists, ACR decided to allow tidal circulation to naturally restore the historic tidal marsh. To benefit from this unique opportunity to observe the development of a tidal marsh system, we designed a five-year research program to track changes in the developing tidal marsh. Thanks to generous funding from the Campini Foundation and Marin Community Foundation, all of the objectives of this study have been completed.
In keeping with the goals of our mission, the results of our research are interpreted through a variety of educational programs that serve people of all ages. Annual reports have been presented to the GFNMS, the National Oceanic and Atmospheric Administration (NOAA), the Point Reyes National Seashore, the California Coastal Commission, and the Marin Community Foundation. Katie Etienne has published several articles about this study in The Ardeid, ACR’s annual newsletter on research and resource management.
In 2003, we repeated all of the physical and biological surveys that were conducted during the previous five years. Pacific Land Surveys conducted the second comprehensive survey of the tidal and brackish marsh and Lauren Hammack provided important collaboration on the analysis of hydro-geomorphic data. All physical and biological survey data have been entered in our computers and we are continuing with analysis and comparison of results with previous biological surveys conducted when Livermore Marsh was a freshwater system.
Etienne, K. L., L. Hammack, and J. P. Kelly. 2004. Influence of re-establishing tidal circulation on inlet geometry, tidal prism and avian use in Livermore Marsh, Tomales Bay, California. ACR Tech. Rpt. 98-10-1. Audubon Canyon Ranch, P.O. Box 808, Marshall, CA 94940.