Bahia Marsh is a 632 acre tidally influenced wetland in Novato (Marin County) tucked just inside the mouth of the Petaluma River. This marsh has been reduced to a fraction of its original size due to dredging, fill, and development (See Figure 1). In 2009, the San Francisco Estuary Partnership received funding from the US EPA’s San Francisco Bay Water Quality Improvement Fund to partner with the Marin Audubon Society (MAS) to restore the most ecologically impaired portion of the Bahia Marshland, Eastern Bahia.
This portion of the Bahia Marsh was filled with dredged bay mud, dried, and compacted in the early 2000’s and prepared for development. Once plans for development fell through, the area was abandoned and subsequently purchased by the MAS. Compacted bay mud makes for incredibly poor site conditions, making restoration very difficult.
The goal of this project was to enhance the tidal marsh ecotone habitat along the two levees, approximately 10.5 total acres, on the Eastern and Western Peninsulas adjacent to 14.5 acres of newly restored tidal marsh. The first effort was to seed the bare dirt with a cover grass to prevent noxious invasive species from colonizing large portions of the peninsula and then to work towards controlling invasives while planting native wetland species (See Figure 2).
This project succeeded in propagating over 12,000 viable rhizomes in onsite nurserys and outplanted over half of them during the project period. In addition, MAS planted nine thickets on the project site composed of various wetland species in different quantities that will serve as a seed bank for the area.
MAS also succeeded in recruiting over 500 volunteers over the project period to remove noxious invasive species from the site. A total of 1,200 volunteer hours went into battling the invasive plants over four annual events.
This project has resulted in effective control of invasive species, but due to the historic drought that coincided with the project period and the incredibly poor site conditions, restoration efforts were not as successful as the project partners had hoped. Increases of native plant coverage ranged from 0% – 19%. As the project was underway, these results led MAS to employ adaptive management and plant the aforementioned thickets. These thickets were planted with DriWater tubes that are carbohydrate gels designed to slowly release water in dry conditions. These, combined with a modest localized soil amendment, led to successful establishment (75% to 100% survival of individual plants) of the thickets.
Restoration of Bahia Marsh in Marin County shows us why SFEP is a partnership. It has taken more than just a village to bring back salt marsh vegetation and some of the Bay Area’s treasured endangered species to former North Bay wetlands turned to dust by diking and dredging. Efforts to restore native species and control invasives continue and the Marine Audubon Society is always looking for individuals and groups to help restore this struggling wetland. If you wish to lend your hand in restoring the Eastern Bahia Marshland, please contact Barbara Salzman at the Marin Audubon Society at [email protected] or contact James Muller at the Estuary Partnership at [email protected]. For more information on the project’s description and results, please review the Final Report. This report includes site descriptions. planting plans, and monitoring results.