Report on the March 5, 2022 Field Trip to the Novato Baylands Nursery & Hamilton Wetlands Restoration

Field Trip Report: by Susan Schlosser

Baylands Stewards meeting room seed sorting area and storage buildingBaylands Stewards meeting room, seed sorting area and storage building

 

 

 

 

 

 

 

 

 

 

The Novato Baylands Stewards have been growing and planting native plants for the Hamilton Wetland Restoration project since 2013.  The Stewards are a well-organized group of 30 – 40 volunteers with an excellent facility for their restoration work. A large building is used for presentations, cleaning and storing seeds, and field gear storage and maintenance. Colorful artwork of wetland plants and animals, created by students and volunteer, is all around you. Our field trip began here with Alycia Matz describing the agricultural and military history of the site. Around the turn of the 20th century, the extensive tidal wetlands along the western edge of San Pablo Bay were diked and drained for agriculture. During the Depression, the Army purchased a large area of these agricultural lands and developed the Hamilton Army Airfield. In 1999 the US Army Core of Engineers and California Coastal Conservancy entered an agreement to restore the Hamilton Army Airfield to a tidal wetland system. After years of planning, design, permitting and construction, the bay-side levee was breached in April 2014. After nearly a century, the Hamilton Wetlands were reconnected to San Francisco Bay. A mix of seasonal and tidal wetlands, uplands,and wildlife corridors with a beautiful section of the San Francisco Bay Trail path are now enjoyed by residents and visitors.

Baylands Stewards NurseryBaylands Stewards NurseryThe Novato Baylands Stewards have been responsible for providing and planting appropriate species to restore the wetlands. Seeds for restoration are collected at fresh, brackish and salt marshes from the Petaluma River to China Camp State Park. We saw a demonstration of methods used to clean and store seeds.see sorting methods demonstrationSeed sorting methods demonstration
Baylands Stewards shaded nurseryBaylands Stewards shaded nurseryThen we went to the outdoor, shade-cloth covered growing area. Here flats of small plants grown from collected seed were along one side of the shade house and in the middle area, plants that had grown sufficiently were transplanted to small tubes. Outside the shaded growing area, larger plants in pots, were grown, watered with fresh or salt water, and kept until ready for planting.  Among the plants we saw in the growing area were Gum Plant (Grindelia stricta), Salt Grass (Distichlis spicata), Mugwort (Artmesia douglasii), Bull Rush (Bolboschoenus maritimus), Farewell to Spring (Clarkia amoena), and Alkalai heath (Frankenia salina).

The Hamilton Wetlands Restoration includes innovative and experimental aspects. The site subsided 7 to 10 feet during the years of agricultural and military use. From 2007 to 2010, dredge material from the Port of Oakland harbor and ship channel deepening project was used to raise the elevation of the Hamilton Wetland Project site to above mean tide level. Since then, tidal exchange has brought in sediment and began shaping complex channel networks characteristic of tidal wetlands.  And of course, all those wetland plants grown by the Novato Baylands Stewards have been planted in various area of the project.

high intertidal mudflats and mid interdial area of the norhern wetlandsHigh intertidal mudflats and mid intertidal area of the northern wetlandsThe Hamilton Wetland Restoration Project is about 800 acres. Designated habitats within the site include northern seasonal wetlands, tidal wetlands, tidal panne, south seasonal wetland, the levee breach, the Bay Trail and a wildlife corridor. We visited the northern seasonal wetlands on our field trip. This wetland system and the southern wetlands are another innovative aspect of the Hamilton Wetlands Restoration Project. Both are high elevation salt marshes that include an upland area on their periphery. The northern seasonal wetlands are actively managed. A levee surrounds the area and a tidal gate controls tidal inflow. In the southern seasonal wetland, passive management occurs in the constructed high elevation areas by passive inundation from the adjacent tidal basin and includes a berm to reduce wave fetch and erosion. The transitional upland area adjacent to both seasonal wetland areas includes a wildlife corridor to support wildlife movement.  In the northern seasonal wetlands we saw recently planted nursery plants and discussed one of the biggish challenges to restoration projects, invasive species.  Right now, the main invasive species at this site are Brass Buttons (Cotula coronopifolia), an Asteraceae naturalized from South Africa, Russian Thistle (Salsola soda), a native of southern Europe that grows well in open areas of salt marshes and mudflats, and Yellow-star thistle (Centaurea solstitialis), a native of the Mediterranean region.

Upland wildlife corridor of northern wetlandsUpland wildlife corridor of northern wetlandsThe field trip leaders pointed out the wetlands adjacent to the site we visited. This is the 1600-acre, Bel Marin Keys Wetlands Restoration Project started in 2014.  This access to this site was not suitable for our field trip.

Overall this was a fascinating field trip. Novato Baylands Stewards contributed to the discussion as did many local residents, some of whom worked at the Hamilton Army Airfield or lived nearby since the 1960’s.  We also enjoyed seeing many species of migratory waterfowl and shorebirds on our walk to the northern seasonal wetlands.  There is still much to be learned from this restoration project.  There are many documents online if you are interested in more information about the Hamilton Wetlands Restoration Project.

All photos by Susan Schlosser.