Delineation of Wetlands and Deepwater Habitats: Giacomini Wetland Restoration Project, Marin County, California

Parsons, Lorraine; Allen, Leslie; Ryan, Amelia

A report describing the a study done for the Giacomini Wetland Restoration Project the goal of which was to map and describe areas within the Delineation Study Area. This report describes the methods and results of a delineation potentially subject to oversight by the California Coastal Commission and National Park Service (Park Service) for the Giacomini Wetland Restoration Project (Project). Point Reyes National Seashore (Seashore), a unit of the Park Service, will be preparing an Environmental Impact Statement/Environmental Impact Report (EIS/EIR) for this Project. The Project Area is located in the southern portion of the Tomales Bay watershed in the county of Marin west of the town of Point Reyes Station and east of the town of Inverness Park. It incorporates the Giacomini Ranch proper, Olema Marsh, portions of Levee and Bear Valley Road, and undiked marsh areas directly adjacent to the Giacomini Ranch. The Delineation Study Area expands the Project Area by including areas directly adjacent that might be impacted by restoration activities. The Project proposes to restore natural hydrologic and ecological processes and functions to a historic coastal marsh that was diked in the 1940s for operation of a dairy. The Park Service purchased the Waldo Giacomini dairy ranch (Giacomini Ranch) in 2000 for the purpose of wetland restoration. Since that time, the Park Service has been working on assessing existing conditions and initiating the planning process. As part of the EIS/EIR, the Seashore must consider whether this Project could impact sensitive vegetation communities such as wetlands, as well as special status wildlife and plant species, water quality, and other environmental and socioeconomic factors. A preferred restoration alternative has not been selected yet, however, most of the alternatives involve some degree of topographic and hydrologic alternation, including levee removal, partial breaching, lowering or regarding of levees, excavation of tidal channels, revegetation with native plant species, etc. The goal of this study was to map and describe areas within the Delineation Study Area potentially subject to Park Service Director’s Order #77-1 and oversight by the California Coastal Commission under the federal Coastal Zone Management Act. A separate report was prepared that assesses acreage of waters potentially subject to regulation by the U.S. Army Corps of Engineers (Corps) under Section 404 of the Clean Water Act and Section 10 of the Rivers and Harbors Act (Parsons 2005). Information from these reports will be used to assess in the environmental document potential impacts of these restoration activities on existing wetlands and waters.