A steady stream of scows began arriving the morning of Dec. 6 just off the coast of Eden Landing, a 6,400-acre ecological reserve located along the eastern shore of San Francisco Bay, depositing nutrient-rich dredge material in the shallow Bay waters about one mile from its tidal marshes. The daily operation, which wrapped up Dec. 31, is part of a $3.6 million shallow water strategic placement pilot project spearheaded by the U.S. Army Corps of Engineers San Francisco District, California State Coastal Conservancy (non-federal project proponent), and monitored by the U.S. Geological Survey.
“Sediment has a very important role to play in preparing the Bay Area for sea level rise, storm surge and other impacts of climate change. Beneficially using dredged sediment to help the bay’s wetlands accrete is an effective and cost-efficient way to maintain these habitats that sustain wildlife and provide critical flood defenses, “said Amy Hutzel, California State Coastal Conservancy executive director. “The Coastal Conservancy partnered with the U.S. Army Corps of Engineers San Francisco District to implement this pilot project in order to gain a better understanding of how the bay’s own sediment can be best utilized to restore and enhance our shoreline.”
This past month, dredgers have been plucking this beneficial-use material from the federal channel at Port of Redwood City in South San Francisco and loading these scows for the short voyage across the bay. Once deposited, the material is slowly moved toward the shore by natural tidal and wind wave action replenishing the mudflats and marshes with much needed sediment. This California Department of Fish and Wildlife-managed reserve is a popular stop for wintering and migrating waterfowl, as well as shorebirds, mammals and fish such as salmon and steelhead.
The three federal and state agencies have partnered on the project to determine if this Engineering With Nature (EWN) approach can be a successful new method to achieve beneficial use for existing mudflats and marshes as they increasingly need low-impact elevation boosts to keep pace with sea level rise.
“EWN allows us to work with the power of water and sediment to efficiently and ideally cost-effectively protect our communities, restore natural systems, and prepare us for the challenges of the future,” said Julie Beagle, USACE San Francisco District EWN practice lead and Environmental Planning Section chief.
Earlier this fall, a team of environmental scientists and coastal engineers from USGS completed pre-project monitoring to understand baseline conditions of the local sediment supply, benthic communities, eelgrass habitats. Following this month’s placement operation, the project will move into a robust post-project monitoring phase. They will use various methods and techniques to determine sediment deposition and impacts from this strategic placement, including a magnetic particle tracking study.
“The San Francisco District is well-positioned to work with partners to develop and implement EWN solutions to manage the risk of flooding in the build environment, restore aquatic ecosystems and continue to meet navigation missions while adapting to new conditions in the face of climate change,” said Beagle.
For more information about the Eden Landing Shallow Water Strategic Placement Pilot Project, please visit www.ewn.erdc.dren.mil/built-projects/section-1122-shallow-water-strategic-placement-pilot-project/.