In 2016, Save The Bay staff and volunteers celebrated the incredible achievement of outplanting 100,000 plants. Of that massive number, 70,560 were tiny sprigs of rhizomatous wetland species planted into the Oro Loma Horizontal Levee Demonstration project (OLHLDP). Designed to advance the science of nature-based solutions, the project was a unique partnership between many entities including the Oro Loma Sanitary District, the San Francisco Estuary Partnership, the San Francisco Estuary Institute, UC Berkeley, ESA, and Peter Baye, a renowned coastal ecologist. Lessons learned from the effort have not only improved how Save The Bay works and informed future horizontal levee projects, but have generated data about how habitats like this may be able to remove harmful contaminants from wastewater.
Testing New Restoration Methods
Save The Bay was brought in to propagate native plant material and to leverage our incredible network of volunteers and supporters in the effort. Joining the project meant challenging ourselves to test new methods, many of which we still use today on our large scale habitat transition zone projects. The native plant propagation for the project was designed to “scale-up” and to reduce the cost of the large numbers of plants typically propagated in a nursery setting. Propagules were sourced locally from native plant communities, well-adapted to the climate and tidal fluctuations of the San Francisco Bay. The majority of plants were grown in a large-scale and low-maintenance method at a division bed nursery constructed next to the project site.
Within an abbreviated timeline, the species chosen for the project thrived, producing healthy rooted stock and greatly surpassing the 70,000 propagules required for outplanting. The resilience and vigorous growth of the chosen moist grassland/bayland ecotone species demonstrated the possibility of bulk propagation using small-scale farming methods to grow and transplant propagules for transition zone projects at a greater scale. Success on this project empowered us to use these same techniques on current projects like the Ravenswood R4 and All American Canal levees as part of the South Bay Salt Pond Restoration Project.
The Site that Keeps on Giving
While our role at the OLHLDP ended with outplanting, the ecotone is still used as a living laboratory by UC Berkeley and contributes to some remarkable science. Anthony DeSalvo and Jonathan Uhler, two current Phd students under Dr David Sedlak, are focused on PFAS and heavy metal removal from wastewater effluent and wastewater reuse concentrate in horizontal levee systems. Further insights gained from the project have informed the design of soon-to-be-implemented projects like the Hayward First Mile and Palo Alto Horizontal Levee.
Successful contaminant removal on the ecotone slope has emboldened regulators to permit the next generation of horizontal levees directly connected to the bay. As the San Francisco Regional Water Quality Control Board (Water Board) issued an updated nutrient discharge permit for wastewater agencies to collectively cut nutrient discharges by about 40% over the next ten years, horizontal levees are a tested, nature-based way to remove contaminants from wastewater. In addition to dense transition zone habitat and improved water quality, new horizontal levees will provide shoreline and natural flood protection and adaptation to sea level rise. Oro Loma Horizontal Levee Demonstration project can be a beacon for a healthier, cleaner future for San Francisco Bay.
