Delineation of Potential Jurisdictional Wetlands and 'Other Waters': Giacomini Wetland Restoration Project, Marin County, California

Parsons, Lorraine

This report describes the methods and results of a delineation of the waters of the Unites States, including special aquatic sites such as wetlands, for the Giacomini Wetland Restoration Project (Project). Point Reyes National Seashore (Seashore), a unit of the National Park Service (Park Service), will be preparing an Environmental Impact Statement/Environmental Impact Report (EIS/EIR) for this Project. The Project proposes to restore natural hydrologic and ecological processes and functions to a historic 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 preliminary alternatives involve some degree of levee and berm alteration and/or removal and grading activities. Information from this report will be used to assess potential impacts of the Project to wetlands and waters subject to regulatory oversight by the U.S. Army Corps of Engineers (Corps). 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 march 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 goal of this study was to map and describe areas within the Delineation Study Area under federal jurisdiction pursuant to section 404 of the federal Clean Water Act and Section 10 of the Rivers and Harbors Act.